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Topolski MA, Gilmore BL, Khondaker R, Michniak JA, Studtmann C, Chen Y, Wagner GN, Pozo-Aranda AE, Farris S, Swanger SA. Input-specific localization of NMDA receptor GluN2 subunits in thalamocortical neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.23.607324. [PMID: 39229083 PMCID: PMC11370540 DOI: 10.1101/2024.08.23.607324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2024]
Abstract
Molecular and functional diversity among synapses is generated, in part, by differential expression of neurotransmitter receptors and their associated protein complexes. N -methyl- D -aspartate receptors (NMDARs) are tetrameric ionotropic glutamate receptors that most often comprise two GluN1 and two GluN2 subunits. NMDARs generate functionally diverse synapses across neuron populations through cell-type-specific expression patterns of GluN2 subunits (GluN2A - 2D), which have vastly different functional properties and distinct downstream signaling. Diverse NMDAR function has also been observed at anatomically distinct inputs to a single neuron population. However, the mechanisms that generate input-specific NMDAR function remain unknown as few studies have investigated subcellular GluN2 subunit localization in native brain tissue. We investigated NMDAR synaptic localization in thalamocortical (TC) neurons expressing all four GluN2 subunits. Utilizing super resolution imaging and knockout-validated antibodies, we revealed subtype- and input-specific GluN2 localization at corticothalamic (CT) versus sensory inputs to TC neurons in 4-week-old male and female C57Bl/6J mice. GluN2B was the most abundant postsynaptic subunit across all glutamatergic synapses followed by GluN2A and GluN2C, and GluN2D was localized to the fewest synapses. GluN2B was preferentially localized to CT synapses over sensory synapses, while GluN2A and GluN2C were more abundant at sensory inputs compared to CT inputs. Furthermore, postsynaptic scaffolding proteins PSD95 and SAP102 were preferentially localized with specific GluN2 subunits, and SAP102 was more abundant at sensory synapses than PSD95. This work indicates that TC neurons exhibit subtype- and input-specific localization of diverse NMDARs and associated scaffolding proteins that likely contribute to functional differences between CT and sensory synapses. HIGHLIGHTS NMDAR subtypes and synaptic scaffolding proteins show preferential localization at specific inputs to thalamocortical neurons.GluN2B was preferentially localized to corticothalamic synapses, while GluN2A and GluN2C were more abundant at sensory inputs to thalamocortical neurons.Colocalization between synaptic scaffolding proteins with NMDARs was GluN2 subtype-dependent.NMDAR subsynaptic organization in thalamocortical neurons is input- and GluN2-subtype specific.
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Studtmann C, Ladislav M, Safari M, Khondaker R, Chen Y, Vaughan GA, Topolski MA, Tomović E, Balík A, Swanger SA. Ventral posterolateral and ventral posteromedial thalamocortical neurons have distinct physiological properties. J Neurophysiol 2023; 130:1492-1507. [PMID: 37937368 PMCID: PMC11068404 DOI: 10.1152/jn.00525.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 10/09/2023] [Accepted: 11/01/2023] [Indexed: 11/09/2023] Open
Abstract
Somatosensory information is propagated from the periphery to the cerebral cortex by two parallel pathways through the ventral posterolateral (VPL) and ventral posteromedial (VPM) thalamus. VPL and VPM neurons receive somatosensory signals from the body and head, respectively. VPL and VPM neurons may also receive cell type-specific GABAergic input from the reticular nucleus of the thalamus. Although VPL and VPM neurons have distinct connectivity and physiological roles, differences in their functional properties remain unclear as they are often studied as one ventrobasal thalamus neuron population. Here, we directly compared synaptic and intrinsic properties of VPL and VPM neurons in C57Bl/6J mice of both sexes aged P25-P32. VPL neurons showed greater depolarization-induced spike firing and spike frequency adaptation than VPM neurons. VPL and VPM neurons fired similar numbers of spikes during hyperpolarization rebound bursts, but VPM neurons exhibited shorter burst latency compared with VPL neurons, which correlated with larger sag potential. VPM neurons had larger membrane capacitance and more complex dendritic arbors. Recordings of spontaneous and evoked synaptic transmission suggested that VPL neurons receive stronger excitatory synaptic input, whereas inhibitory synapse strength was stronger in VPM neurons. This work indicates that VPL and VPM thalamocortical neurons have distinct intrinsic and synaptic properties. The observed functional differences could have important implications for their specific physiological and pathophysiological roles within the somatosensory thalamocortical network.NEW & NOTEWORTHY This study revealed that somatosensory thalamocortical neurons in the VPL and VPM have substantial differences in excitatory synaptic input and intrinsic firing properties. The distinct properties suggest that VPL and VPM neurons could process somatosensory information differently and have selective vulnerability to disease. This work improves our understanding of nucleus-specific neuron function in the thalamus and demonstrates the critical importance of studying these parallel somatosensory pathways separately.
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Affiliation(s)
- Carleigh Studtmann
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, United States
- Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, Virginia, United States
| | - Marek Ladislav
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, United States
| | - Mona Safari
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, United States
- Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, Virginia, United States
| | - Rabeya Khondaker
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, United States
- Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, Virginia, United States
| | - Yang Chen
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, United States
- Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, Virginia, United States
| | - Grace A Vaughan
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, United States
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, Blacksburg, Virginia, United States
| | - Mackenzie A Topolski
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, United States
| | - Eni Tomović
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, United States
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Aleš Balík
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Sharon A Swanger
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, United States
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States
- Department of Internal Medicine, Virginia Tech Carilion School of Medicine, Roanoke, Virginia, United States
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Sheroziya M, Khazipov R. Synaptic Origin of Early Sensory-evoked Oscillations in the Immature Thalamus. Neuroscience 2023; 532:50-64. [PMID: 37769898 DOI: 10.1016/j.neuroscience.2023.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 08/22/2023] [Accepted: 09/08/2023] [Indexed: 10/03/2023]
Abstract
During the critical period of postnatal development, brain maturation is extremely sensitive to external stimuli. Newborn rodents already have functional somatosensory pathways and the thalamus, but the cortex is still forming. Immature thalamic synapses may produce large postsynaptic potentials in immature neurons, while non-synaptic membrane currents remain relatively weak and slow. The thalamocortical system generates spontaneous and evoked early gamma and spindle-burst oscillations in newborn rodents. How relatively strong synapses and weak intrinsic currents interact with each other and how they contribute to early thalamic activities remains largely unknown. Here, we performed local field potential (LFP), juxtacellular, and patch-clamp recordings in the somatosensory thalamus of urethane-anesthetized rat pups at postnatal days 6-7 with one whisker stimulation. We removed the overlying cortex and hippocampus to reach the thalamus with electrodes. Deflection of only one (the principal) whisker induced spikes in a particular thalamic cell. Whisker deflection evoked a group of large-amplitude excitatory events, likely originating from lemniscal synapses and multiple inhibitory postsynaptic events in thalamocortical cells. Large-amplitude excitatory events produced a group of spike bursts and could evoke a depolarization block. Juxtacellular recordings confirmed the partial inactivation of spikes. Inhibitory events prevented inactivation of action potentials and gamma-modulated neuronal firing. We conclude that the interplay of strong excitatory and inhibitory synapses and relatively weak intrinsic currents produces sensory-evoked early gamma oscillations in thalamocortical cells. We also propose that sensory-evoked large-amplitude excitatory events contribute to evoked spindle-bursts.
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Affiliation(s)
- Maxim Sheroziya
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.
| | - Roustem Khazipov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia; Aix Marseille University, INSERM, INMED, Marseille, France
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Ueta Y, Miyata M. Functional and structural synaptic remodeling mechanisms underlying somatotopic organization and reorganization in the thalamus. Neurosci Biobehav Rev 2023; 152:105332. [PMID: 37524138 DOI: 10.1016/j.neubiorev.2023.105332] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/09/2023] [Accepted: 07/27/2023] [Indexed: 08/02/2023]
Abstract
The somatosensory system organizes the topographic representation of body maps, termed somatotopy, at all levels of an ascending hierarchy. Postnatal maturation of somatotopy establishes optimal somatosensation, whereas deafferentation in adults reorganizes somatotopy, which underlies pathological somatosensation, such as phantom pain and complex regional pain syndrome. Here, we focus on the mouse whisker somatosensory thalamus to study how sensory experience shapes the fine topography of afferent connectivity during the critical period and what mechanisms remodel it and drive a large-scale somatotopic reorganization after peripheral nerve injury. We will review our findings that, following peripheral nerve injury in adults, lemniscal afferent synapses onto thalamic neurons are remodeled back to immature configuration, as if the critical period reopens. The remodeling process is initiated with local activation of microglia in the brainstem somatosensory nucleus downstream to injured nerves and heterosynaptically controlled by input from GABAergic and cortical neurons to thalamic neurons. These fruits of thalamic studies complement well-studied cortical mechanisms of somatotopic organization and reorganization and unveil potential intervention points in treating pathological somatosensation.
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Affiliation(s)
- Yoshifumi Ueta
- Division of Neurophysiology, Department of Physiology, School of Medicine, Tokyo Women's Medical University, Tokyo 162-8666, Japan
| | - Mariko Miyata
- Division of Neurophysiology, Department of Physiology, School of Medicine, Tokyo Women's Medical University, Tokyo 162-8666, Japan.
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Thalamic control of sensory processing and spindles in a biophysical somatosensory thalamoreticular circuit model of wakefulness and sleep. Cell Rep 2023; 42:112200. [PMID: 36867532 PMCID: PMC10066598 DOI: 10.1016/j.celrep.2023.112200] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 01/04/2023] [Accepted: 02/15/2023] [Indexed: 03/04/2023] Open
Abstract
Thalamoreticular circuitry plays a key role in arousal, attention, cognition, and sleep spindles, and is linked to several brain disorders. A detailed computational model of mouse somatosensory thalamus and thalamic reticular nucleus has been developed to capture the properties of over 14,000 neurons connected by 6 million synapses. The model recreates the biological connectivity of these neurons, and simulations of the model reproduce multiple experimental findings in different brain states. The model shows that inhibitory rebound produces frequency-selective enhancement of thalamic responses during wakefulness. We find that thalamic interactions are responsible for the characteristic waxing and waning of spindle oscillations. In addition, we find that changes in thalamic excitability control spindle frequency and their incidence. The model is made openly available to provide a new tool for studying the function and dysfunction of the thalamoreticular circuitry in various brain states.
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Studtmann C, Ladislav M, Topolski MA, Safari M, Swanger SA. NaV1.1 haploinsufficiency impairs glutamatergic and GABAergic neuron function in the thalamus. Neurobiol Dis 2022; 167:105672. [DOI: 10.1016/j.nbd.2022.105672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 02/08/2022] [Accepted: 02/22/2022] [Indexed: 11/16/2022] Open
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Wright NC, Borden PY, Liew YJ, Bolus MF, Stoy WM, Forest CR, Stanley GB. Rapid Cortical Adaptation and the Role of Thalamic Synchrony during Wakefulness. J Neurosci 2021; 41:5421-5439. [PMID: 33986072 PMCID: PMC8221593 DOI: 10.1523/jneurosci.3018-20.2021] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 03/18/2021] [Accepted: 04/29/2021] [Indexed: 12/14/2022] Open
Abstract
Rapid sensory adaptation is observed across all sensory systems, and strongly shapes sensory percepts in complex sensory environments. Yet despite its ubiquity and likely necessity for survival, the mechanistic basis is poorly understood. A wide range of primarily in vitro and anesthetized studies have demonstrated the emergence of adaptation at the level of primary sensory cortex, with only modest signatures in earlier stages of processing. The nature of rapid adaptation and how it shapes sensory representations during wakefulness, and thus the potential role in perceptual adaptation, is underexplored, as are the mechanisms that underlie this phenomenon. To address these knowledge gaps, we recorded spiking activity in primary somatosensory cortex (S1) and the upstream ventral posteromedial (VPm) thalamic nucleus in the vibrissa pathway of awake male and female mice, and quantified responses to whisker stimuli delivered in isolation and embedded in an adapting sensory background. We found that cortical sensory responses were indeed adapted by persistent sensory stimulation; putative excitatory neurons were profoundly adapted, and inhibitory neurons only modestly so. Further optogenetic manipulation experiments and network modeling suggest this largely reflects adaptive changes in synchronous thalamic firing combined with robust engagement of feedforward inhibition, with little contribution from synaptic depression. Taken together, these results suggest that cortical adaptation in the regime explored here results from changes in the timing of thalamic input, and the way in which this differentially impacts cortical excitation and feedforward inhibition, pointing to a prominent role of thalamic gating in rapid adaptation of primary sensory cortex.SIGNIFICANCE STATEMENT Rapid adaptation of sensory activity strongly shapes representations of sensory inputs across all sensory pathways over the timescale of seconds, and has profound effects on sensory perception. Despite its ubiquity and theoretical role in the efficient encoding of complex sensory environments, the mechanistic basis is poorly understood, particularly during wakefulness. In this study in the vibrissa pathway of awake mice, we show that cortical representations of sensory inputs are strongly shaped by rapid adaptation, and that this is mediated primarily by adaptive gating of the thalamic inputs to primary sensory cortex and the differential way in which these inputs engage cortical subpopulations of neurons.
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Affiliation(s)
- Nathaniel C Wright
- Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332
| | - Peter Y Borden
- Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332
| | - Yi Juin Liew
- Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, Georgia 30332 and Beijing University, Beijing China 100871
| | - Michael F Bolus
- Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332
| | - William M Stoy
- Department of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Craig R Forest
- Department of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Garrett B Stanley
- Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332
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8
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Leong ATL, Wang X, Wong EC, Dong CM, Wu EX. Neural activity temporal pattern dictates long-range propagation targets. Neuroimage 2021; 235:118032. [PMID: 33836268 DOI: 10.1016/j.neuroimage.2021.118032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 03/24/2021] [Accepted: 03/30/2021] [Indexed: 11/30/2022] Open
Abstract
Brain possesses a complex spatiotemporal architecture for efficient information processing and computing. However, it remains unknown how neural signal propagates to its intended targets brain-wide. Using optogenetics and functional MRI, we arbitrarily initiated various discrete neural activity pulse trains with different temporal patterns and revealed their distinct long-range propagation targets within the well-defined, topographically organized somatosensory thalamo-cortical circuit. We further observed that such neural activity propagation over long range could modulate brain-wide sensory functions. Electrophysiological analysis indicated that distinct propagation pathways arose from system level neural adaptation and facilitation in response to the neural activity temporal characteristics. Together, our findings provide fundamental insights into the long-range information transfer and processing. They directly support that temporal coding underpins the whole brain functional architecture in presence of the vast and relatively static anatomical architecture.
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Affiliation(s)
- Alex T L Leong
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR
| | - Xunda Wang
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR
| | - Eddie C Wong
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR
| | - Celia M Dong
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR
| | - Ed X Wu
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR; School of Biomedical Sciences, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR.
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9
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Whitmire CJ, Liew YJ, Stanley GB. Thalamic state influences timing precision in the thalamocortical circuit. J Neurophysiol 2021; 125:1833-1850. [PMID: 33760642 DOI: 10.1152/jn.00261.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Sensory signals from the outside world are transduced at the periphery, passing through thalamus before reaching cortex, ultimately giving rise to the sensory representations that enable us to perceive the world. The thalamocortical circuit is particularly sensitive to the temporal precision of thalamic spiking due to highly convergent synaptic connectivity. Thalamic neurons can exhibit burst and tonic modes of firing that strongly influence timing within the thalamus. The impact of these changes in thalamic state on sensory encoding in the cortex, however, remains unclear. Here, we investigated the role of thalamic state on timing in the thalamocortical circuit of the vibrissa pathway in the anesthetized rat. We optogenetically hyperpolarized thalamus while recording single unit activity in both thalamus and cortex. Tonic spike-triggered analysis revealed temporally precise thalamic spiking that was locked to weak white-noise sensory stimuli, whereas thalamic burst spiking was associated with a loss in stimulus-locked temporal precision. These thalamic state-dependent changes propagated to cortex such that the cortical timing precision was diminished during the hyperpolarized (burst biased) thalamic state. Although still sensory driven, the cortical neurons became significantly less precisely locked to the weak white-noise stimulus. The results here suggests a state-dependent differential regulation of spike timing precision in the thalamus that could gate what signals are ultimately propagated to cortex.NEW & NOTEWORTHY The majority of sensory signals are transmitted through the thalamus. There is growing evidence of complex thalamic gating through coordinated firing modes that have a strong impact on cortical sensory representations. Optogenetic hyperpolarization of thalamus pushed it into burst firing that disrupted precise time-locked sensory signaling, with a direct impact on the downstream cortical encoding, setting the stage for a timing-based thalamic gate of sensory signaling.
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Affiliation(s)
- Clarissa J Whitmire
- Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Yi Juin Liew
- Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia.,Joint PhD Program in Biomedical Engineering, Georgia Institute of Technology-Emory University-Peking University, Atlanta, Georgia
| | - Garrett B Stanley
- Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
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10
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Burns TF, Rajan R. Sensing and processing whisker deflections in rodents. PeerJ 2021; 9:e10730. [PMID: 33665005 PMCID: PMC7906041 DOI: 10.7717/peerj.10730] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 12/17/2020] [Indexed: 11/20/2022] Open
Abstract
The classical view of sensory information mainly flowing into barrel cortex at layer IV, moving up for complex feature processing and lateral interactions in layers II and III, then down to layers V and VI for output and corticothalamic feedback is becoming increasingly undermined by new evidence. We review the neurophysiology of sensing and processing whisker deflections, emphasizing the general processing and organisational principles present along the entire sensory pathway—from the site of physical deflection at the whiskers to the encoding of deflections in the barrel cortex. Many of these principles support the classical view. However, we also highlight the growing number of exceptions to these general principles, which complexify the system and which investigators should be mindful of when interpreting their results. We identify gaps in the literature for experimentalists and theorists to investigate, not just to better understand whisker sensation but also to better understand sensory and cortical processing.
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Affiliation(s)
- Thomas F Burns
- Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Ramesh Rajan
- Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
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11
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Kwak H, Koh W, Kim S, Song K, Shin JI, Lee JM, Lee EH, Bae JY, Ha GE, Oh JE, Park YM, Kim S, Feng J, Lee SE, Choi JW, Kim KH, Kim YS, Woo J, Lee D, Son T, Kwon SW, Park KD, Yoon BE, Lee J, Li Y, Lee H, Bae YC, Lee CJ, Cheong E. Astrocytes Control Sensory Acuity via Tonic Inhibition in the Thalamus. Neuron 2020; 108:691-706.e10. [PMID: 32905785 DOI: 10.1016/j.neuron.2020.08.013] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 07/05/2020] [Accepted: 08/14/2020] [Indexed: 12/17/2022]
Abstract
Sensory discrimination is essential for survival. However, how sensory information is finely controlled in the brain is not well defined. Here, we show that astrocytes control tactile acuity via tonic inhibition in the thalamus. Mechanistically, diamine oxidase (DAO) and the subsequent aldehyde dehydrogenase 1a1 (Aldh1a1) convert putrescine into GABA, which is released via Best1. The GABA from astrocytes inhibits synaptically evoked firing at the lemniscal synapses to fine-tune the dynamic range of the stimulation-response relationship, the precision of spike timing, and tactile discrimination. Our findings reveal a novel role of astrocytes in the control of sensory acuity through tonic GABA release.
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Affiliation(s)
- Hankyul Kwak
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea
| | - Wuhyun Koh
- Division of Bio-Medical Science &Technology, KIST School, Korea University of Science and Technology, Seoul 02792, South Korea; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology, Seoul 02792, South Korea; Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, South Korea
| | - Sangwoo Kim
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea
| | - Kiyeong Song
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea
| | - Jeong-Im Shin
- Division of Bio-Medical Science &Technology, KIST School, Korea University of Science and Technology, Seoul 02792, South Korea; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Jung Moo Lee
- Center for Glia-Neuron Interaction, Korea Institute of Science and Technology, Seoul 02792, South Korea; Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, South Korea; KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, South Korea
| | - Elliot H Lee
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea
| | - Jin Young Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 41566, South Korea
| | - Go Eun Ha
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea
| | - Ju-Eun Oh
- Molecular Recognition Research Center, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Yongmin Mason Park
- Division of Bio-Medical Science &Technology, KIST School, Korea University of Science and Technology, Seoul 02792, South Korea; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology, Seoul 02792, South Korea; Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, South Korea
| | - Sunpil Kim
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, South Korea; KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, South Korea
| | - Jiesi Feng
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
| | - Seung Eun Lee
- Virus Facility, Research Animal Resource Center, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Ji Won Choi
- Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Ki Hun Kim
- Doping Control Center, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Yoo Sung Kim
- Department of Molecular Biology, College of Natural Science, Dankook University, Cheonan 31116, South Korea
| | - Junsung Woo
- Center for Glia-Neuron Interaction, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Dongsu Lee
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea
| | - Taehwang Son
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, South Korea
| | - Soon Woo Kwon
- Radiation Medicine Clinical Research Division, Korea Institute of Radiological and Medical Sciences, Seoul, South Korea
| | - Ki Duk Park
- Division of Bio-Medical Science &Technology, KIST School, Korea University of Science and Technology, Seoul 02792, South Korea; Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Korea Institute of Science and Technology, Seoul 02792, South Korea; KHU-KIST Department of Converging Science and Technology, Kyung Hee University, Seoul 02447, South Korea
| | - Bo-Eun Yoon
- Department of Molecular Biology, College of Natural Science, Dankook University, Cheonan 31116, South Korea
| | - Jaeick Lee
- Doping Control Center, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China; PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China
| | - Hyunbeom Lee
- Molecular Recognition Research Center, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Yong Chul Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 41566, South Korea
| | - C Justin Lee
- Division of Bio-Medical Science &Technology, KIST School, Korea University of Science and Technology, Seoul 02792, South Korea; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology, Seoul 02792, South Korea; Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, South Korea.
| | - Eunji Cheong
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, South Korea; POSTECH Biotech Center, POSTECH, Pohang, South Korea.
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12
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Azimi H, Klaassen AL, Thomas K, Harvey MA, Rainer G. Role of the Thalamus in Basal Forebrain Regulation of Neural Activity in the Primary Auditory Cortex. Cereb Cortex 2020; 30:4481-4495. [PMID: 32244254 DOI: 10.1093/cercor/bhaa045] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Many studies have implicated the basal forebrain (BF) as a potent regulator of sensory encoding even at the earliest stages of or cortical processing. The source of this regulation involves the well-documented corticopetal cholinergic projections from BF to primary cortical areas. However, the BF also projects to subcortical structures, including the thalamic reticular nucleus (TRN), which has abundant reciprocal connections with sensory thalamus. Here we present naturalistic auditory stimuli to the anesthetized rat while making simultaneous single-unit recordings from the ventral medial geniculate nucleus (MGN) and primary auditory cortex (A1) during electrical stimulation of the BF. Like primary visual cortex, we find that BF stimulation increases the trial-to-trial reliability of A1 neurons, and we relate these results to change in the response properties of MGN neurons. We discuss several lines of evidence that implicate the BF to thalamus pathway in the manifestation of BF-induced changes to cortical sensory processing and support our conclusions with supplementary TRN recordings, as well as studies in awake animals showing a strong relationship between endogenous BF activity and A1 reliability. Our findings suggest that the BF subcortical projections that modulate MGN play an important role in auditory processing.
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Affiliation(s)
- H Azimi
- Department of Medicine, University of Fribourg, Fribourg CH-1700, Switzerland
| | - A-L Klaassen
- Department of Medicine, University of Fribourg, Fribourg CH-1700, Switzerland.,Department of Psychology, University of Fribourg, Fribourg CH-1700, Switzerland
| | - K Thomas
- Department of Medicine, University of Fribourg, Fribourg CH-1700, Switzerland
| | - M A Harvey
- Department of Medicine, University of Fribourg, Fribourg CH-1700, Switzerland
| | - G Rainer
- Department of Medicine, University of Fribourg, Fribourg CH-1700, Switzerland
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Neonatal general anesthesia causes lasting alterations in excitatory and inhibitory synaptic transmission in the ventrobasal thalamus of adolescent female rats. Neurobiol Dis 2019; 127:472-481. [PMID: 30825640 DOI: 10.1016/j.nbd.2019.01.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 01/22/2019] [Accepted: 01/24/2019] [Indexed: 12/25/2022] Open
Abstract
Ample evidence has surfaced documenting the neurotoxic effects of various general anesthetic (GA) agents in the mammalian brain when administered at critical periods of synaptogenesis. However, little is known about how this neurotoxic insult affects persisting neuronal excitability after the initial exposure. Here we investigated synaptic activity and intrinsic excitability of the ventrobasal nucleus (VB) of the thalamus caused by neonatal GA administration. We used patch-clamp recordings from acute thalamic slices in young rats up to two weeks after neurotoxic GA exposure of isoflurane and nitrous oxide for 6 h at postnatal age of 7 (P7) days. We found that GA exposure at P7 increases evoked excitatory postsynaptic currents (eEPSCs) two fold by means through AMPA mediated mechanisms, while NMDA component was spared. In addition, miniature EPSCs showed a faster decay rate in neurons from GA treated animals when compared to sham controls. Likewise, we discovered that the amplitudes of evoked inhibitory postsynaptic currents (eIPSCs) were increased in VB neurons from GA animals about two-fold. Interestingly, these results were observed in female but not male rats. In contrast, intrinsic excitability and properties of T-type voltage gated calcium currents were minimally affected by GA exposure. Together, these data further the idea that GAs cause lasting alterations in synaptic transmission and neuronal excitability depending upon the placing and connectivity of neurons in the thalamus. Given that function of thalamocortical circuits critically depends on the delicate balance between excitation and inhibition, future development of therapies aimed at addressing consequences of altered excitability in the developing brain by GAs may be an attractive possibility.
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Gribkova ED, Ibrahim BA, Llano DA. A novel mutual information estimator to measure spike train correlations in a model thalamocortical network. J Neurophysiol 2018; 120:2730-2744. [PMID: 30183459 PMCID: PMC6337027 DOI: 10.1152/jn.00012.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 09/03/2018] [Accepted: 09/04/2018] [Indexed: 01/28/2023] Open
Abstract
The impact of thalamic state on information transmission to the cortex remains poorly understood. This limitation exists due to the rich dynamics displayed by thalamocortical networks and because of inadequate tools to characterize those dynamics. Here, we introduce a novel estimator of mutual information and use it to determine the impact of a computational model of thalamic state on information transmission. Using several criteria, this novel estimator, which uses an adaptive partition, is shown to be superior to other mutual information estimators with uniform partitions when used to analyze simulated spike train data with different mean spike rates, as well as electrophysiological data from simultaneously recorded neurons. When applied to a thalamocortical model, the estimator revealed that thalamocortical cell T-type calcium current conductance influences mutual information between the input and output from this network. In particular, a T-type calcium current conductance of ~40 nS appears to produce maximal mutual information between the input to this network (conceptualized as afferent input to the thalamocortical cell) and the output of the network at the level of a layer 4 cortical neuron. Furthermore, at particular combinations of inputs to thalamocortical and thalamic reticular nucleus cells, thalamic cell bursting correlated strongly with recovery of mutual information between thalamic afferents and layer 4 neurons. These studies suggest that the novel mutual information estimator has advantages over previous estimators and that thalamic reticular nucleus activity can enhance mutual information between thalamic afferents and thalamorecipient cells in the cortex. NEW & NOTEWORTHY In this study, a novel mutual information estimator was developed to analyze information flow in a model thalamocortical network. Our findings suggest that this estimator is a suitable tool for signal transmission analysis, particularly in neural circuits with disparate firing rates, and that the thalamic reticular nucleus can potentiate ascending sensory signals, while thalamic recipient cells in the cortex can recover mutual information in ascending sensory signals that is lost due to thalamic bursting.
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Affiliation(s)
- Ekaterina D Gribkova
- Neuroscience Program, University of Illinois at Urbana-Champaign , Urbana, Illinois
- Beckman Institute for Advanced Science and Technology , Urbana, Illinois
| | - Baher A Ibrahim
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign , Urbana, Illinois
- Beckman Institute for Advanced Science and Technology , Urbana, Illinois
| | - Daniel A Llano
- Neuroscience Program, University of Illinois at Urbana-Champaign , Urbana, Illinois
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign , Urbana, Illinois
- Beckman Institute for Advanced Science and Technology , Urbana, Illinois
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15
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Leyrer-Jackson JM, Thomas MP. Subtype-specific effects of dopaminergic D2 receptor activation on synaptic trains in layer V pyramidal neurons in the mouse prefrontal cortex. Physiol Rep 2018; 5:5/22/e13499. [PMID: 29150590 PMCID: PMC5704077 DOI: 10.14814/phy2.13499] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 10/06/2017] [Accepted: 10/10/2017] [Indexed: 11/24/2022] Open
Abstract
In humans, prefrontal cortical areas are known to support executive functions. In mice, these functions are mediated by homologous regions in the medial prefrontal cortex (mPFC). Executive processes are critically dependent on optimal levels of dopamine (DA), but the cellular mechanisms of DA modulation are incompletely understood. Stable patterns of neuronal activity may be sensitive to frequency-dependent changes in synaptic transmission. We characterized the effects of D2 receptor (D2R) activation on short-term excitatory postsynaptic potential (EPSP) dynamics evoked at varying frequencies in the two subtypes of layer V pyramidal neurons in mouse mPFC We isolated NMDA receptor and non-NMDA receptor-mediated components of EPSP trains evoked by stimulating fibers within layer V or layer I. All significant effects of D2 receptor activation were confined to type I (corticopontine) cells. First, we found that with layer I stimulation, D2R activation reduces the amplitude of NMDAR-mediated EPSPs, with no effect on facilitation or depression of these responses at lower frequencies, but leading to facilitation with high frequency stimulation. Further, the non-NMDA component also underwent synaptic depression at low frequencies. Second, with layer V stimulation, D2R activation had no effect on NMDA or non-NMDA receptor-mediated EPSP components. Overall, our results suggest that D2R activation may modulate memory functions by inhibiting 'top-down' influences from apical tuft inputs activated at low frequencies, while promoting 'top-down' influences from inputs activated at higher frequencies. These data provide further insight into mechanisms of dopamine's modulation of executive functions.
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Affiliation(s)
- Jonna M Leyrer-Jackson
- University of Northern Colorado School of Biological Sciences University of Northern Colorado, Greeley, Colorado
| | - Mark P Thomas
- University of Northern Colorado School of Biological Sciences University of Northern Colorado, Greeley, Colorado
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16
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Collins DP, Anastasiades PG, Marlin JJ, Carter AG. Reciprocal Circuits Linking the Prefrontal Cortex with Dorsal and Ventral Thalamic Nuclei. Neuron 2018; 98:366-379.e4. [PMID: 29628187 DOI: 10.1016/j.neuron.2018.03.024] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 02/01/2018] [Accepted: 03/14/2018] [Indexed: 12/12/2022]
Abstract
Reciprocal interactions between the prefrontal cortex (PFC) and thalamus play a critical role in cognition, but the underlying circuits remain poorly understood. Here we use optogenetics to dissect the specificity and dynamics of cortico-thalamo-cortical networks in the mouse brain. We find that cortico-thalamic (CT) neurons in prelimbic PFC project to both mediodorsal (MD) and ventromedial (VM) thalamus, where layer 5 and 6 inputs activate thalamo-cortical (TC) neurons with distinct temporal profiles. We show that TC neurons in MD and VM in turn make distinct connections in PFC, with MD preferentially and strongly activating layer 2/3 cortico-cortical (CC) neurons. Finally, we assess local connections from superficial CC to deep CT neurons, which link thalamo-cortical and cortico-thalamic networks within the PFC. Together our findings indicate that PFC strongly drives neurons in the thalamus, whereas MD and VM indirectly influence reciprocally connected neurons in the PFC, providing a mechanistic understanding of these circuits.
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Affiliation(s)
- David P Collins
- Center for Neural Science, New York University, 4 Washington Place, New York, NY 10003, USA
| | - Paul G Anastasiades
- Center for Neural Science, New York University, 4 Washington Place, New York, NY 10003, USA
| | - Joseph J Marlin
- Center for Neural Science, New York University, 4 Washington Place, New York, NY 10003, USA
| | - Adam G Carter
- Center for Neural Science, New York University, 4 Washington Place, New York, NY 10003, USA.
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17
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Perissinotti PP, Rivero-Echeto MC, Garcia-Rill E, Bisagno V, Urbano FJ. Leptin alters somatosensory thalamic networks by decreasing gaba release from reticular thalamic nucleus and action potential frequency at ventrobasal neurons. Brain Struct Funct 2018. [PMID: 29520482 DOI: 10.1007/s00429-018-1645-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Leptin is an adipose-derived hormone that controls appetite and energy expenditure. Leptin receptors are expressed on extra-hypothalamic ventrobasal (VB) and reticular thalamic (RTN) nuclei from embryonic stages. Here, we studied the effects of pressure-puff, local application of leptin on both synaptic transmission and action potential properties of thalamic neurons in thalamocortical slices. We used whole-cell patch-clamp recordings of thalamocortical VB neurons from wild-type (WT) and leptin-deficient obese (ob/ob) mice. We observed differences in VB neurons action potentials and synaptic currents kinetics when comparing WT vs. ob/ob. Leptin reduced GABA release onto VB neurons throughout the activation of a JAK2-dependent pathway, without affecting excitatory glutamate transmission. We observed a rapid and reversible reduction by leptin of the number of action potentials of VB neurons via the activation of large conductance Ca2+-dependent potassium channels. These leptin effects were observed in thalamocortical slices from up to 5-week-old WT but not in leptin-deficient obese mice. Results described here suggest the existence of a leptin-mediated trophic modulation of thalamocortical excitability during postnatal development. These findings could contribute to a better understanding of leptin within the thalamocortical system and sleep deficits in obesity.
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Affiliation(s)
- Paula P Perissinotti
- Departamento de Fisiología, Facultad de Ciencias Exactas y Naturales, Biología Molecular y Celular "Dr. Héctor Maldonado", Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, C1428EGA, Ciudad Autónoma de Buenos Aires, Argentina
| | - María Celeste Rivero-Echeto
- Departamento de Fisiología, Facultad de Ciencias Exactas y Naturales, Biología Molecular y Celular "Dr. Héctor Maldonado", Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, C1428EGA, Ciudad Autónoma de Buenos Aires, Argentina
| | - Edgar Garcia-Rill
- Department of Neurobiology and Developmental Sciences, Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Verónica Bisagno
- Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
- Instituto de Investigaciones Farmacológicas (ININFA), CONICET-Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Francisco J Urbano
- Departamento de Fisiología, Facultad de Ciencias Exactas y Naturales, Biología Molecular y Celular "Dr. Héctor Maldonado", Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina.
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, C1428EGA, Ciudad Autónoma de Buenos Aires, Argentina.
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18
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Allitt BJ, Alwis DS, Rajan R. Laminar-specific encoding of texture elements in rat barrel cortex. J Physiol 2017; 595:7223-7247. [PMID: 28929510 PMCID: PMC5709323 DOI: 10.1113/jp274865] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 09/06/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS For rats texture discrimination is signalled by the large face whiskers by stick-slip events. Neural encoding of repetitive stick-slip events will be influenced by intrinsic properties of adaptation. We show that texture coding in the barrel cortex is laminar specific and follows a power function. Our results also show layer 2 codes for novel feature elements via robust firing rates and temporal fidelity. We conclude that texture coding relies on a subtle neural ensemble to provide important object information. ABSTRACT Texture discrimination by rats is exquisitely guided by fine-grain mechanical stick-slip motions of the face whiskers as they encounter, stick to and slip past successive texture-defining surface features such as bumps and grooves. Neural encoding of successive stick-slip texture events will be shaped by adaptation, common to all sensory systems, whereby receptor and neural responses to a stimulus are affected by responses to preceding stimuli, allowing resetting to signal novel information. Additionally, when a whisker is actively moved to contact and brush over surfaces, that motion itself generates neural responses that could cause adaptation of responses to subsequent stick-slip events. Nothing is known about encoding in the rat whisker system of stick-slip events defining textures of different grain or the influence of adaptation from whisker protraction or successive texture-defining stick-slip events. Here we recorded responses from halothane-anaesthetized rats in response to texture-defining stimuli applied to passive whiskers. We demonstrate that: across the columnar network of the whisker-recipient barrel cortex, adaptation in response to repetitive stick-slip events is strongest in uppermost layers and equally lower thereafter; neither whisker protraction speed nor stick-slip frequency impede encoding of stick-slip events at rates up to 34.08 Hz; and layer 2 normalizes responses to whisker protraction to resist effects on texture signalling. Thus, within laminar-specific response patterns, barrel cortex reliably encodes texture-defining elements even to high frequencies.
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Affiliation(s)
| | - Dasuni S. Alwis
- Department of PhysiologyMonash UniversityClaytonVIC3800Australia
| | - Ramesh Rajan
- Department of PhysiologyMonash UniversityClaytonVIC3800Australia
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Synaptic properties of the lemniscal and paralemniscal pathways to the mouse somatosensory thalamus. Proc Natl Acad Sci U S A 2017; 114:E6212-E6221. [PMID: 28696281 PMCID: PMC5544298 DOI: 10.1073/pnas.1703222114] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Somatosensory information is thought to arrive in thalamus through two glutamatergic routes called the lemniscal and paralemniscal pathways via the ventral posterior medial (VPm) and posterior medial (POm) nuclei. Here we challenge the view that these pathways functionally represent parallel information routes. Using electrical stimulation and an optogenetic approach in brain slices from the mouse, we investigated the synaptic properties of the lemniscal and paralemniscal input to VPm and POm. Stimulation of the lemniscal pathway produced class 1, or "driver," responses in VPm relay cells, which is consistent with this being an information-bearing channel. However, stimulation of the paralemniscal pathway produced two distinct types of responses in POm relay cells: class 1 (driver) responses in 29% of the cells, and class 2, or "modulator," responses in the rest. Our data suggest that, unlike the lemniscal pathway, the paralemniscal one is not homogenous and that it is primarily modulatory. This finding requires major rethinking regarding the routes of somatosensory information to cortex and suggests that the paralemniscal route is chiefly involved in modulatory functions rather than simply being an information route parallel to the lemniscal channel.
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20
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Kim K, Müller MLTM, Bohnen NI, Sarter M, Lustig C. Thalamic cholinergic innervation makes a specific bottom-up contribution to signal detection: Evidence from Parkinson's disease patients with defined cholinergic losses. Neuroimage 2017; 149:295-304. [PMID: 28167350 DOI: 10.1016/j.neuroimage.2017.02.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 01/10/2017] [Accepted: 02/02/2017] [Indexed: 12/13/2022] Open
Abstract
Successful behavior depends on the ability to detect and respond to relevant cues, especially under challenging conditions. This essential component of attention has been hypothesized to be mediated by multiple neuromodulator systems, but the contributions of individual systems (e.g., cholinergic, dopaminergic) have remained unclear. The present study addresses this issue by leveraging individual variation in regionally-specific cholinergic denervation in Parkinson's disease (PD) patients, while controlling for variation in dopaminergic denervation. Patients whose dopaminergic and cholinergic nerve terminal integrity had been previously assessed using Positron Emission Tomography (Bohnen et al., 2012) and controls were tested in a signal detection task that manipulates attentional-perceptual challenge and has been used extensively in both rodents and humans to investigate the cholinergic system's role in responding to such challenges (Demeter et al., 2008; McGaughy and Sarter, 1995; see Hasselmo and Sarter 2011 for review). In simple correlation analyses, measures of midbrain dopaminergic, and both cortical and thalamic cholinergic innervation all predicted preserved signal detection under challenge. However, regression analyses also controlling for age, disease severity, and other variables showed that the only significant independent neurotransmitter-related predictor over and above the other variables in the model was thalamic cholinergic integrity. Furthermore, thalamic cholinergic innervation exclusively predicted hits, not correct rejections, indicating a specific contribution to bottom-up salience processing. These results help define regionally-specific contributions of cholinergic function to different aspects of attention and behavior.
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Affiliation(s)
- Kamin Kim
- Department of Psychology, University of Michigan, Ann Arbor, MI 48109, United States.
| | - Martijn L T M Müller
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109, United States; University of Michigan Morris K. Udall Center of Excellence for Parkinson's Disease Research, Ann Arbor, MI 48109, United States
| | - Nicolaas I Bohnen
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109, United States; Department of Neurology, University of Michigan, Ann Arbor, MI 48109, United States; University of Michigan Morris K. Udall Center of Excellence for Parkinson's Disease Research, Ann Arbor, MI 48109, United States; Veterans Affairs Ann Arbor Healthcare System, Ann Arbor, MI 48109, United States
| | - Martin Sarter
- Department of Psychology, University of Michigan, Ann Arbor, MI 48109, United States; Neuroscience Program, University of Michigan, Ann Arbor, MI 48109, United States; University of Michigan Morris K. Udall Center of Excellence for Parkinson's Disease Research, Ann Arbor, MI 48109, United States
| | - Cindy Lustig
- Department of Psychology, University of Michigan, Ann Arbor, MI 48109, United States; Neuroscience Program, University of Michigan, Ann Arbor, MI 48109, United States; University of Michigan Morris K. Udall Center of Excellence for Parkinson's Disease Research, Ann Arbor, MI 48109, United States.
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21
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Long-range projections coordinate distributed brain-wide neural activity with a specific spatiotemporal profile. Proc Natl Acad Sci U S A 2016; 113:E8306-E8315. [PMID: 27930323 DOI: 10.1073/pnas.1616361113] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
One challenge in contemporary neuroscience is to achieve an integrated understanding of the large-scale brain-wide interactions, particularly the spatiotemporal patterns of neural activity that give rise to functions and behavior. At present, little is known about the spatiotemporal properties of long-range neuronal networks. We examined brain-wide neural activity patterns elicited by stimulating ventral posteromedial (VPM) thalamo-cortical excitatory neurons through combined optogenetic stimulation and functional MRI (fMRI). We detected robust optogenetically evoked fMRI activation bilaterally in primary visual, somatosensory, and auditory cortices at low (1 Hz) but not high frequencies (5-40 Hz). Subsequent electrophysiological recordings indicated interactions over long temporal windows across thalamo-cortical, cortico-cortical, and interhemispheric callosal projections at low frequencies. We further observed enhanced visually evoked fMRI activation during and after VPM stimulation in the superior colliculus, indicating that visual processing was subcortically modulated by low-frequency activity originating from VPM. Stimulating posteromedial complex thalamo-cortical excitatory neurons also evoked brain-wide blood-oxygenation-level-dependent activation, although with a distinct spatiotemporal profile. Our results directly demonstrate that low-frequency activity governs large-scale, brain-wide connectivity and interactions through long-range excitatory projections to coordinate the functional integration of remote brain regions. This low-frequency phenomenon contributes to the neural basis of long-range functional connectivity as measured by resting-state fMRI.
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22
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Li L, Ebner FF. Cortex dynamically modulates responses of thalamic relay neurons through prolonged circuit-level disinhibition in rat thalamus in vivo. J Neurophysiol 2016; 116:2368-2382. [PMID: 27582292 DOI: 10.1152/jn.00424.2016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 08/29/2016] [Indexed: 11/22/2022] Open
Abstract
Cortex actively modulates the responses of thalamic relay neurons through corticothalamic (CT) projections. Here we investigated the temporal precision of CT modulation on sensory responses of relay neurons in rat ventral posterior medial thalamus (VPM) to direction-specific whisker stimuli. CT feedback levels were either augmented by cortical electrical microstimulation or depressed by cortical application of muscimol, a potent agonist of γ-aminobutyric acid A-type (GABAA) receptors. To evaluate the temporal specificity of CT influence, we compared the early (3-10 ms after stimulus onset) and late (10-100 ms) response components of VPM single units to whisker deflections in preferred or nonpreferred directions before and after altering CT feedback levels under urethane anesthesia. The data showed that cortical feedback most strongly affected the late responses of single VPM units to whisker stimulation. That is, cortical stimulation consistently increased the late responses of VPM units in the corresponding (homologous) barreloids to the stimulus direction preferred by neurons in the cortical locus stimulated. However, cortical stimulation could either increase or decrease the early response, depending on whether or not cortical and thalamic loci were tuned to the same direction. Such bidirectional regulation of the early and late VPM responses is consistent with a mechanism of circuit-level disinhibition in vivo. The results support the theory that CT feedback on thalamic sensory responses is mediated by a time-dependent shift of the excitation-inhibition balance in the thalamo-cortico-thalamic loop, such as would occur during sensory feature integration, plasticity, and learning in the awake state.
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Affiliation(s)
- Lu Li
- Allen Institute for Brain Science, Seattle, Washington; and
| | - Ford F Ebner
- Department of Psychology, Vanderbilt University, Nashville, Tennessee
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23
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Jubran M, Mohar B, Lampl I. The Transformation of Adaptation Specificity to Whisker Identity from Brainstem to Thalamus. Front Syst Neurosci 2016; 10:56. [PMID: 27445716 PMCID: PMC4917531 DOI: 10.3389/fnsys.2016.00056] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Accepted: 06/09/2016] [Indexed: 01/15/2023] Open
Abstract
Stimulus specific adaptation has been studied extensively in different modalities. High specificity implies that deviant stimulus induces a stronger response compared to a common stimulus. The thalamus gates sensory information to the cortex, therefore, the specificity of adaptation in the thalamus must have a great impact on cortical processing of sensory inputs. We studied the specificity of adaptation to whisker identity in the ventral posteromedial nucleus of the thalamus (VPM) in rats using extracellular and intracellular recordings. We found that subsequent to repetitive stimulation that induced strong adaptation, the response to stimulation of the same, or any other responsive whisker was equally adapted, indicating that thalamic adaptation is non-specific. In contrast, adaptation of single units in the upstream brainstem principal trigeminal nucleus (PrV) was significantly more specific. Depolarization of intracellularly recorded VPM cells demonstrated that adaptation is not due to buildup of inhibition. In addition, adaptation increased the probability of observing complete synaptic failures to tactile stimulation. In accordance with short-term synaptic depression models, the evoked synaptic potentials in response to whisker stimulation, subsequent to a response failure, were facilitated. In summary, we show that local short-term synaptic plasticity is involved in the transformation of adaptation in the trigemino-thalamic synapse and that the low specificity of adaptation in the VPM emerges locally rather than cascades from earlier stages. Taken together we suggest that during sustained stimulation, local thalamic mechanisms equally suppress inputs arriving from different whiskers before being gated to the cortex.
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Affiliation(s)
- Muna Jubran
- Department of Neurobiology, Weizmann Institute of Science Rehovot, Israel
| | - Boaz Mohar
- Department of Neurobiology, Weizmann Institute of Science Rehovot, Israel
| | - Ilan Lampl
- Department of Neurobiology, Weizmann Institute of Science Rehovot, Israel
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24
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Lo FS, Erzurumlu RS. Sensory Activity-Dependent and Sensory Activity-Independent Properties of the Developing Rodent Trigeminal Principal Nucleus. Dev Neurosci 2016; 38:163-170. [PMID: 27287019 DOI: 10.1159/000446395] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 04/24/2016] [Indexed: 11/19/2022] Open
Abstract
The whisker-sensory trigeminal central pathway of rodents is an established model for studies of activity-dependent neural plasticity. The first relay station of the pathway is the trigeminal principal nucleus (PrV), the ventral part of which receives sensory inputs mainly from the infraorbital branch of the maxillary trigeminal nerve (ION). Whisker-sensory afferents play an important role in the development of the morphological and physiological properties of PrV neurons. In neonates, deafferentation by ION transection leads to the disruption of whisker-related neural patterns (barrelettes) and cell death within a specific time window (critical period), as revealed by morphological studies. Whisker-sensory inputs control synaptic elimination, postsynaptic AMPA receptor trafficking, astrocyte-mediated synaptogenesis, and receptive-field characteristics of PrV cells, without a postnatal critical period. Sensory activity-dependent synaptic plasticity requires the activation of NMDA receptors and involves the participation of glia. However, the basic physiological properties of PrV neurons, such as cell type-specific ion channels, presynaptic terminal function, postsynaptic NMDA receptor subunit composition, and formation of the inhibitory circuitry, are independent of sensory inputs. Therefore, the first relay station of the whisker sensation is largely mature-like and functional at birth. Delineation of activity-dependent and activity-independent features of the postnatal PrV is important for understanding the development and functional characteristics of downstream trigeminal stations in the thalamus and neocortex. This mini review focuses on such features of the developing rodent PrV.
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Affiliation(s)
- Fu-Sun Lo
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Md., USA
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Castro-Alamancos MA, Favero M. Whisker-related afferents in superior colliculus. J Neurophysiol 2016; 115:2265-79. [PMID: 26864754 DOI: 10.1152/jn.00028.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 02/03/2016] [Indexed: 11/22/2022] Open
Abstract
Rodents use their whiskers to explore the environment, and the superior colliculus is part of the neural circuits that process this sensorimotor information. Cells in the intermediate layers of the superior colliculus integrate trigeminotectal afferents from trigeminal complex and corticotectal afferents from barrel cortex. Using histological methods in mice, we found that trigeminotectal and corticotectal synapses overlap somewhat as they innervate the lower and upper portions of the intermediate granular layer, respectively. Using electrophysiological recordings and optogenetics in anesthetized mice in vivo, we showed that, similar to rats, whisker deflections produce two successive responses that are driven by trigeminotectal and corticotectal afferents. We then employed in vivo and slice experiments to characterize the response properties of these afferents. In vivo, corticotectal responses triggered by electrical stimulation of the barrel cortex evoke activity in the superior colliculus that increases with stimulus intensity and depresses with increasing frequency. In slices from adult mice, optogenetic activation of channelrhodopsin-expressing trigeminotectal and corticotectal fibers revealed that cells in the intermediate layers receive more efficacious trigeminotectal, than corticotectal, synaptic inputs. Moreover, the efficacy of trigeminotectal inputs depresses more strongly with increasing frequency than that of corticotectal inputs. The intermediate layers of superior colliculus appear to be tuned to process strong but infrequent trigeminal inputs and weak but more persistent cortical inputs, which explains features of sensory responsiveness, such as the robust rapid sensory adaptation of whisker responses in the superior colliculus.
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Affiliation(s)
- Manuel A Castro-Alamancos
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Morgana Favero
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
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Castejon C, Barros-Zulaica N, Nuñez A. Control of Somatosensory Cortical Processing by Thalamic Posterior Medial Nucleus: A New Role of Thalamus in Cortical Function. PLoS One 2016; 11:e0148169. [PMID: 26820514 PMCID: PMC4731153 DOI: 10.1371/journal.pone.0148169] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 01/13/2016] [Indexed: 11/19/2022] Open
Abstract
Current knowledge of thalamocortical interaction comes mainly from studying lemniscal thalamic systems. Less is known about paralemniscal thalamic nuclei function. In the vibrissae system, the posterior medial nucleus (POm) is the corresponding paralemniscal nucleus. POm neurons project to L1 and L5A of the primary somatosensory cortex (S1) in the rat brain. It is known that L1 modifies sensory-evoked responses through control of intracortical excitability suggesting that L1 exerts an influence on whisker responses. Therefore, thalamocortical pathways targeting L1 could modulate cortical firing. Here, using a combination of electrophysiology and pharmacology in vivo, we have sought to determine how POm influences cortical processing. In our experiments, single unit recordings performed in urethane-anesthetized rats showed that POm imposes precise control on the magnitude and duration of supra- and infragranular barrel cortex whisker responses. Our findings demonstrated that L1 inputs from POm imposed a time and intensity dependent regulation on cortical sensory processing. Moreover, we found that blocking L1 GABAergic inhibition or blocking P/Q-type Ca2+ channels in L1 prevents POm adjustment of whisker responses in the barrel cortex. Additionally, we found that POm was also controlling the sensory processing in S2 and this regulation was modulated by corticofugal activity from L5 in S1. Taken together, our data demonstrate the determinant role exerted by the POm in the adjustment of somatosensory cortical processing and in the regulation of cortical processing between S1 and S2. We propose that this adjustment could be a thalamocortical gain regulation mechanism also present in the processing of information between cortical areas.
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Affiliation(s)
- Carlos Castejon
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| | - Natali Barros-Zulaica
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| | - Angel Nuñez
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
- * E-mail:
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Connelly WM, Laing M, Errington AC, Crunelli V. The Thalamus as a Low Pass Filter: Filtering at the Cellular Level does Not Equate with Filtering at the Network Level. Front Neural Circuits 2016; 9:89. [PMID: 26834570 PMCID: PMC4712306 DOI: 10.3389/fncir.2015.00089] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 12/22/2015] [Indexed: 11/20/2022] Open
Abstract
In the mammalian central nervous system, most sensory information passes through primary sensory thalamic nuclei, however the consequence of this remains unclear. Various propositions exist, likening the thalamus to a gate, or a high pass filter. Here, using a simple leaky integrate and fire model based on physiological parameters, we show that the thalamus behaves akin to a low pass filter. Specifically, as individual cells in the thalamus rely on consistent drive to spike, stimuli that is rapidly and continuously changing over time such that it activates sensory cells with different receptive fields are unable to drive thalamic spiking. This means that thalamic encoding is robust to sensory noise, however it induces a lag in sensory representation. Thus, the thalamus stabilizes encoding of sensory information, at the cost of response rate.
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Affiliation(s)
- William M Connelly
- Division of Neuroscience, School of Biosciences, Cardiff UniversityCardiff, UK; Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National UniversityCanberra, ACT, Australia
| | - Michael Laing
- School of Medicine, Neuroscience and Mental Health Research Institute, Cardiff University Cardiff, UK
| | - Adam C Errington
- School of Medicine, Neuroscience and Mental Health Research Institute, Cardiff University Cardiff, UK
| | - Vincenzo Crunelli
- Division of Neuroscience, School of Biosciences, Cardiff UniversityCardiff, UK; Department of Physiology and Biochemistry, University of MaltaMsida, Malta
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28
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Lo FS, Erzurumlu RS. Neonatal sensory nerve injury-induced synaptic plasticity in the trigeminal principal sensory nucleus. Exp Neurol 2016; 275 Pt 2:245-52. [PMID: 25956829 PMCID: PMC4636484 DOI: 10.1016/j.expneurol.2015.04.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 04/29/2015] [Indexed: 11/26/2022]
Abstract
Sensory deprivation studies in neonatal mammals, such as monocular eye closure, whisker trimming, and chemical blockade of the olfactory epithelium have revealed the importance of sensory inputs in brain wiring during distinct critical periods. But very few studies have paid attention to the effects of neonatal peripheral sensory nerve damage on synaptic wiring of the central nervous system (CNS) circuits. Peripheral somatosensory nerves differ from other special sensory afferents in that they are more prone to crush or severance because of their locations in the body. Unlike the visual and auditory afferents, these nerves show regenerative capabilities after damage. Uniquely, damage to a somatosensory peripheral nerve does not only block activity incoming from the sensory receptors but also mediates injury-induced neuro- and glial chemical signals to the brain through the uninjured central axons of the primary sensory neurons. These chemical signals can have both far more and longer lasting effects than sensory blockade alone. Here we review studies which focus on the consequences of neonatal peripheral sensory nerve damage in the principal sensory nucleus of the brainstem trigeminal complex.
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Affiliation(s)
- Fu-Sun Lo
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
| | - Reha S Erzurumlu
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Urbain N, Salin PA, Libourel PA, Comte JC, Gentet LJ, Petersen CCH. Whisking-Related Changes in Neuronal Firing and Membrane Potential Dynamics in the Somatosensory Thalamus of Awake Mice. Cell Rep 2015; 13:647-656. [PMID: 26489463 DOI: 10.1016/j.celrep.2015.09.029] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 06/26/2015] [Accepted: 09/09/2015] [Indexed: 11/29/2022] Open
Abstract
The thalamus transmits sensory information to the neocortex and receives neocortical, subcortical, and neuromodulatory inputs. Despite its obvious importance, surprisingly little is known about thalamic function in awake animals. Here, using intracellular and extracellular recordings in awake head-restrained mice, we investigate membrane potential dynamics and action potential firing in the two major thalamic nuclei related to whisker sensation, the ventral posterior medial nucleus (VPM) and the posterior medial group (Pom), which receive distinct inputs from brainstem and neocortex. We find heterogeneous state-dependent dynamics in both nuclei, with an overall increase in action potential firing during active states. Whisking increased putative lemniscal and corticothalamic excitatory inputs onto VPM and Pom neurons, respectively. A subpopulation of VPM cells fired spikes phase-locked to the whisking cycle during free whisking, and these cells may therefore signal whisker position. Our results suggest differential processing of whisking comparing thalamic nuclei at both sub- and supra-threshold levels.
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Affiliation(s)
- Nadia Urbain
- Laboratory of Sensory Processing, Brain Mind Institute, Faculty of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland; Physiopathologie des Réseaux Neuronaux du Cycle Sommeil, Centre de Recherche en Neurosciences de Lyon, INSERM U1028-CNRS UMR5292, Université Claude-Bernard-Lyon 1, 69372 Lyon, France.
| | - Paul A Salin
- Physiopathologie des Réseaux Neuronaux du Cycle Sommeil, Centre de Recherche en Neurosciences de Lyon, INSERM U1028-CNRS UMR5292, Université Claude-Bernard-Lyon 1, 69372 Lyon, France
| | - Paul-Antoine Libourel
- Physiopathologie des Réseaux Neuronaux du Cycle Sommeil, Centre de Recherche en Neurosciences de Lyon, INSERM U1028-CNRS UMR5292, Université Claude-Bernard-Lyon 1, 69372 Lyon, France
| | - Jean-Christophe Comte
- Integrated Physiology of Brain Arousal Systems, Centre de Recherche en Neurosciences de Lyon, INSERM U1028-CNRS UMR5292, Université Claude-Bernard-Lyon 1, 69372 Lyon, France
| | - Luc J Gentet
- Integrated Physiology of Brain Arousal Systems, Centre de Recherche en Neurosciences de Lyon, INSERM U1028-CNRS UMR5292, Université Claude-Bernard-Lyon 1, 69372 Lyon, France
| | - Carl C H Petersen
- Laboratory of Sensory Processing, Brain Mind Institute, Faculty of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
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30
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Bale MR, Ince RAA, Santagata G, Petersen RS. Efficient population coding of naturalistic whisker motion in the ventro-posterior medial thalamus based on precise spike timing. Front Neural Circuits 2015; 9:50. [PMID: 26441549 PMCID: PMC4585317 DOI: 10.3389/fncir.2015.00050] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 09/03/2015] [Indexed: 11/24/2022] Open
Abstract
The rodent whisker-associated thalamic nucleus (VPM) contains a somatotopic map where whisker representation is divided into distinct neuronal sub-populations, called “barreloids”. Each barreloid projects to its associated cortical barrel column and so forms a gateway for incoming sensory stimuli to the barrel cortex. We aimed to determine how the population of neurons within one barreloid encodes naturalistic whisker motion. In rats, we recorded the extracellular activity of up to nine single neurons within a single barreloid, by implanting silicon probes parallel to the longitudinal axis of the barreloids. We found that play-back of texture-induced whisker motion evoked sparse responses, timed with millisecond precision. At the population level, there was synchronous activity: however, different subsets of neurons were synchronously active at different times. Mutual information between population responses and whisker motion increased near linearly with population size. When normalized to factor out firing rate differences, we found that texture was encoded with greater informational-efficiency than white noise. These results indicate that, within each VPM barreloid, there is a rich and efficient population code for naturalistic whisker motion based on precisely timed, population spike patterns.
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Affiliation(s)
- Michael R Bale
- School of Life Sciences, University of Sussex Brighton, UK ; Faculty of Life Sciences, University of Manchester Manchester, UK ; Instituto de Neurociencias Alicante UMH-CSIC Sant Joan d'Alacant, Spain
| | - Robin A A Ince
- Faculty of Life Sciences, University of Manchester Manchester, UK ; Institute of Neuroscience and Psychology, University of Glasgow Glasgow, UK
| | - Greta Santagata
- Faculty of Life Sciences, University of Manchester Manchester, UK
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31
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Song W, Semework M. Tactile representation in somatosensory thalamus (VPL) and cortex (S1) of awake primate and the plasticity induced by VPL neuroprosthetic stimulation. Brain Res 2015; 1625:301-13. [PMID: 26348987 DOI: 10.1016/j.brainres.2015.08.046] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 08/20/2015] [Accepted: 08/31/2015] [Indexed: 11/19/2022]
Abstract
To further understand how tactile information is carried in somatosensory cortex (S1) and the thalamus (VPL), and how neuronal plasticity after neuroprosthetic stimulation affects sensory encoding, we chronically implanted microelectrode arrays across hand areas in both S1 and VPL, where neuronal activities were simultaneously recorded during tactile stimulation on the finger pad of awake monkeys. Tactile information encoded in the firing rate of individual units (rate coding) or in the synchrony of unit pairs (synchrony coding) was quantitatively assessed within the information theoretic-framework. We found that tactile information encoded in VPL was higher than that encoded in S1 for both rate coding and synchrony coding; rate coding carried greater information than synchrony coding for the same recording area. With the aim for neuroprosthetic stimulation, plasticity of the circuit was tested after 30 min of VPL electrical stimulation, where stimuli were delivered either randomly or contingent on the spiking of an S1 unit. We showed that neural encoding in VPL was more stable than in S1, which depends not only on the thalamic input but also on recurrent feedback. The percent change of mutual-information after stimulation was increased with closed-loop stimulation, but decreased with random stimulation. The underlying mechanisms during closed-loop stimulation might be spike-timing-dependent plasticity, while frequency-dependent synaptic plasticity might play a role in random stimulation. Our results suggest that VPL could be a promising target region for somatosensory stimulation with closed-loop brain-machine-interface applications.
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Affiliation(s)
- Weiguo Song
- Department of Physiology and Pharmacology, SUNY Downstate Medical Center, NY 11203, USA.
| | - Mulugeta Semework
- Joint Graduate Program in Biomedical Engineering SUNY Downstate and NYU-POLY, NY 11203, USA
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32
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Crandall SR, Cruikshank SJ, Connors BW. A corticothalamic switch: controlling the thalamus with dynamic synapses. Neuron 2015; 86:768-82. [PMID: 25913856 DOI: 10.1016/j.neuron.2015.03.040] [Citation(s) in RCA: 188] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 02/13/2015] [Accepted: 03/12/2015] [Indexed: 01/28/2023]
Abstract
Corticothalamic neurons provide massive input to the thalamus. This top-down projection may allow the cortex to regulate sensory processing by modulating the excitability of thalamic cells. Layer 6 corticothalamic neurons monosynaptically excite thalamocortical cells, but also indirectly inhibit them by driving inhibitory cells of the thalamic reticular nucleus. Whether corticothalamic activity generally suppresses or excites the thalamus remains unclear. Here we show that the corticothalamic influence is dynamic, with the excitatory-inhibitory balance shifting in an activity-dependent fashion. During low-frequency activity, corticothalamic effects are mainly suppressive, whereas higher-frequency activity (even a short bout of gamma frequency oscillations) converts the corticothalamic influence to enhancement. The mechanism of this switching depends on distinct forms of short-term synaptic plasticity across multiple corticothalamic circuit components. Our results reveal an activity-dependent mechanism by which corticothalamic neurons can bidirectionally switch the excitability and sensory throughput of the thalamus, possibly to meet changing behavioral demands.
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Affiliation(s)
- Shane R Crandall
- Department of Neuroscience, Brown University, 185 Meeting Street, Box G-LN, Providence, RI 02912, USA
| | - Scott J Cruikshank
- Department of Neuroscience, Brown University, 185 Meeting Street, Box G-LN, Providence, RI 02912, USA
| | - Barry W Connors
- Department of Neuroscience, Brown University, 185 Meeting Street, Box G-LN, Providence, RI 02912, USA.
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33
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Martin-Cortecero J, Nuñez A. Tactile response adaptation to whisker stimulation in the lemniscal somatosensory pathway of rats. Brain Res 2014; 1591:27-37. [DOI: 10.1016/j.brainres.2014.10.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 09/17/2014] [Accepted: 10/01/2014] [Indexed: 11/29/2022]
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34
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Thalamic NMDA receptor function is necessary for patterning of the thalamocortical somatosensory map and for sensorimotor behaviors. J Neurosci 2014; 34:12001-14. [PMID: 25186746 DOI: 10.1523/jneurosci.1663-14.2014] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
NMDARs play a major role in patterning of topographic sensory maps in the brain. Genetic knock-out of the essential subunit of NMDARs in excitatory cortical neurons prevents whisker-specific neural pattern formation in the barrel cortex. To determine the role of NMDARs en route to the cortex, we generated sensory thalamus-specific NR1 (Grin1)-null mice (ThNR1KO). A multipronged approach, using histology, electrophysiology, optical imaging, and behavioral testing revealed that, in these mice, whisker patterns develop in the trigeminal brainstem but do not develop in the somatosensory thalamus. Subsequently, there is no barrel formation in the neocortex yet a partial afferent patterning develops. Whisker stimulation evokes weak cortical activity and presynaptic neurotransmitter release probability is also affected. We found several behavioral deficits in tasks, ranging from sensorimotor to social and cognitive. Collectively, these results show that thalamic NMDARs play a critical role in the patterning of the somatosensory thalamic and cortical maps and their impairment may lead to pronounced behavioral defects.
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Abstract
The superior colliculus is part of a broader neural network that can decode whisker movements in air and on objects, which is a strategy used by behaving rats to sense the environment. The intermediate layers of the superior colliculus receive whisker-related excitatory afferents from the trigeminal complex and barrel cortex, inhibitory afferents from extrinsic and intrinsic sources, and neuromodulatory afferents from cholinergic and monoaminergic nuclei. However, it is not well known how these inputs regulate whisker-related activity in the superior colliculus. We found that barrel cortex afferents drive the superior colliculus during the middle portion of the rising phase of the whisker movement protraction elicited by artificial (fictive) whisking in anesthetized rats. In addition, both spontaneous and whisker-related neural activities in the superior colliculus are under strong inhibitory and neuromodulator control. Cholinergic stimulation activates the superior colliculus by increasing spontaneous firing and, in some cells, whisker-evoked responses. Monoaminergic stimulation has the opposite effects. The actions of neuromodulator and inhibitory afferents may be the basis of the different firing rates and sensory responsiveness observed in the superior colliculus of behaving animals during distinct behavioral states.
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Abstract
A major synaptic input to the thalamus originates from neurons in cortical layer 6 (L6); however, the function of this cortico-thalamic pathway during sensory processing is not well understood. In the mouse whisker system, we found that optogenetic stimulation of L6 in vivo results in a mixture of hyperpolarization and depolarization in the thalamic target neurons. The hyperpolarization was transient, and for longer L6 activation (>200 ms), thalamic neurons reached a depolarized resting membrane potential which affected key features of thalamic sensory processing. Most importantly, L6 stimulation reduced the adaptation of thalamic responses to repetitive whisker stimulation, thereby allowing thalamic neurons to relay higher frequencies of sensory input. Furthermore, L6 controlled the thalamic response mode by shifting thalamo-cortical transmission from bursting to single spiking. Analysis of intracellular sensory responses suggests that L6 impacts these thalamic properties by controlling the resting membrane potential and the availability of the transient calcium current IT, a hallmark of thalamic excitability. In summary, L6 input to the thalamus can shape both the overall gain and the temporal dynamics of sensory responses that reach the cortex.
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Large-scale somatotopic refinement via functional synapse elimination in the sensory thalamus of developing mice. J Neurosci 2014; 34:1258-70. [PMID: 24453317 DOI: 10.1523/jneurosci.3865-13.2014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Functional synapse elimination and strengthening are crucial developmental processes in the formation of precise neuronal circuits in the somatosensory system, but the underlying alterations in topographical organization are not yet fully understood. To address this issue, we generated transgenic mice in which afferent fibers originating from the whisker-related brain region, called the maxillary principal trigeminal nucleus (PrV2), were selectively visualized with genetically expressed fluorescent protein. We found that functional synapse elimination drove and established large-scale somatotopic refinement even after the thalamic barreloid architecture was formed. Before functional synapse elimination, the whisker sensory thalamus was innervated by afferent fibers not only from the PrV2, but also from the brainstem nuclei representing other body parts. Most notably, only afferent fibers from PrV2 onto a whisker sensory thalamic neuron selectively survived and were strengthened, whereas other afferent fibers were preferentially eliminated via their functional synapse elimination. This large-scale somatotopic refinement was at least partially dependent on somatosensory experience. These novel results uncovered a previously unrecognized role of developmental synapse elimination in the large-scale, instead of the fine-scale, somatotopic refinement even after the initial segregation of the barreloid map.
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Rowe DL, Hermens DF. Attention-deficit/hyperactivity disorder: neurophysiology, information processing, arousal and drug development. Expert Rev Neurother 2014; 6:1721-34. [PMID: 17144785 DOI: 10.1586/14737175.6.11.1721] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this review, we draw on literature from both animal and human neurophysiological studies to consider the neurochemical mechanisms underlying attention-deficit/ hyperactivity disorder (ADHD). Psychophysiological and neuropsychological research is used to propose possible etiological endophenotypes of ADHD. These are conceptualized as patients with distinct cortical-arousal, information-processing or maturational abnormalities, or a combination thereof, and how the endophenotypes can be used to help drug development and optimize treatment and management. To illustrate, the paper focuses on neuro- and psychophysiological evidence that suggests cholinergic mechanisms may underlie specific information-processing abnormalities that occur in ADHD. The clinical implications for a cholinergic hypothesis of ADHD are considered, along with its possible implications for treatment and pharmacological development.
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Affiliation(s)
- Donald L Rowe
- The Brain Dynamics Centre and Department of Psychological Medicine, Westmead Hospital and University of Sydney, NSW, Australia.
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39
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Maravall M, Alenda A, Bale MR, Petersen RS. Transformation of adaptation and gain rescaling along the whisker sensory pathway. PLoS One 2013; 8:e82418. [PMID: 24349279 PMCID: PMC3859573 DOI: 10.1371/journal.pone.0082418] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 10/24/2013] [Indexed: 11/18/2022] Open
Abstract
Neurons in all sensory systems have a remarkable ability to adapt their sensitivity to the statistical structure of the sensory signals to which they are tuned. In the barrel cortex, firing rate adapts to the variance of a whisker stimulus and neuronal sensitivity (gain) adjusts in inverse proportion to the stimulus standard deviation. To determine how adaptation might be transformed across the ascending lemniscal pathway, we measured the responses of single units in the first and last subcortical stages, the trigeminal ganglion (TRG) and ventral posterior medial thalamic nucleus (VPM), to controlled whisker stimulation in urethane-anesthetized rats. We probed adaptation using a filtered white noise stimulus that switched between low- and high-variance epochs. We found that the firing rate of both TRG and VPM neurons adapted to stimulus variance. By fitting the responses of each unit to a Linear-Nonlinear-Poisson model, we tested whether adaptation changed feature selectivity and/or sensitivity. We found that, whereas feature selectivity was unaffected by stimulus variance, units often exhibited a marked change in sensitivity. The extent of these sensitivity changes increased systematically along the pathway from TRG to barrel cortex. However, there was marked variability across units, especially in VPM. In sum, in the whisker system, the adaptation properties of subcortical neurons are surprisingly diverse. The significance of this diversity may be that it contributes to a rich population representation of whisker dynamics.
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Affiliation(s)
- Miguel Maravall
- Instituto de Neurociencias de Alicante, Consejo Superior de Investigaciones Científicas-Universidad Miguel Hernández, Sant Joan d'Alacant, Alicante, Spain
- * E-mail: (MM); (RSP)
| | - Andrea Alenda
- Instituto de Neurociencias de Alicante, Consejo Superior de Investigaciones Científicas-Universidad Miguel Hernández, Sant Joan d'Alacant, Alicante, Spain
| | - Michael R. Bale
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Rasmus S. Petersen
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
- * E-mail: (MM); (RSP)
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Evaluation of the effectiveness of pregabalin in alleviating pain associated with fibromyalgia: using functional magnetic resonance imaging study. PLoS One 2013; 8:e74099. [PMID: 24040178 PMCID: PMC3765321 DOI: 10.1371/journal.pone.0074099] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 07/29/2013] [Indexed: 11/30/2022] Open
Abstract
Purpose To assess the efficacy of pregabalin by showing differences in the neuronal activities of fibromyalgia (FM) patients before and after longitudinal treatment using functional magnetic resonance imaging (fMRI). Materials and Methods In total, 21 female patients with FM and 11 age- and gender-matched healthy controls participated. FM patients underwent fMRI at baseline and following pharmacological therapy with pregabalin to diminish their pain. Pressure-pain stimuli were delivered on the subject’s thumbnail bed during fMRI scans. Brain activation regions in fMRI were evaluated for longitudinal changes using a paired t-test. Changes in clinical features were also assessed with the Fibromyalgia Impact Questionnaire (FIQ), Brief Fatigue Inventory (BFI), Beck Depression Inventory (BDI), Widespread Pain Index (WPI), Symptom Severity Scale Score (SSS), and State-Trait Anxiety Inventory (STAI). Results Clinical scores were reduced significantly following therapy with five of the six clinical tests (FIQ, BFI, BDI, WPI, SSS; p < 0.05). Brain activation post-treatment was significantly lower than that pre-treatment in 13 regions of the brain (p < 0.001). Conclusions Our findings confirm that pregabalin influences aspects of the whole pain matrix, using fMRI, inducing longitudinal changes in neuronal activity during the pain state, and that it reduces pain and other core symptoms of FM. This method could be applied to other longitudinal clinical trials of pharmacological treatments for FM.
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41
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Sanchez-Jimenez A, Torets C, Panetsos F. Complementary processing of haptic information by slowly and rapidly adapting neurons in the trigeminothalamic pathway. Electrophysiology, mathematical modeling and simulations of vibrissae-related neurons. Front Cell Neurosci 2013; 7:79. [PMID: 23761732 PMCID: PMC3671571 DOI: 10.3389/fncel.2013.00079] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 05/08/2013] [Indexed: 11/13/2022] Open
Abstract
TONIC (SLOWLY ADAPTING) AND PHASIC (RAPIDLY ADAPTING) PRIMARY AFFERENTS CONVEY COMPLEMENTARY ASPECTS OF HAPTIC INFORMATION TO THE CENTRAL NERVOUS SYSTEM: object location and texture the former, shape the latter. Tonic and phasic neural responses are also recorded in all relay stations of the somatosensory pathway, yet it is unknown their role in both, information processing and information transmission to the cortex: we don't know if tonic and phasic neurons process complementary aspects of haptic information and/or if these two types constitute two separate channels that convey complementary aspects of tactile information to the cortex. Here we propose to elucidate these two questions in the fast trigeminal pathway of the rat (PrV-VPM: principal trigeminal nucleus-ventroposteromedial thalamic nucleus). We analyze early and global behavior, latencies and stability of the responses of individual cells in PrV and medial lemniscus under 1-40 Hz stimulation of the whiskers in control and decorticated animals and we use stochastic spiking models and extensive simulations. Our results strongly suggest that in the first relay station of the somatosensory system (PrV): (1) tonic and phasic neurons process complementary aspects of whisker-related tactile information (2) tonic and phasic responses are not originated from two different types of neurons (3) the two responses are generated by the differential action of the somatosensory cortex on a unique type of PrV cell (4) tonic and phasic neurons do not belong to two different channels for the transmission of tactile information to the thalamus (5) trigeminothalamic transmission is exclusively performed by tonically firing neurons and (6) all aspects of haptic information are coded into low-pass, band-pass, and high-pass filtering profiles of tonically firing neurons. Our results are important for both, basic research on neural circuits and information processing, and development of sensory neuroprostheses.
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Affiliation(s)
- Abel Sanchez-Jimenez
- Department of Applied Mathematics (Biomathematics), Faculty of Biology, Complutense University of Madrid Madrid, Spain ; Neurocomputing and Neurorobotics Research Group, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Universidad Complutense de Madrid Madrid, Spain
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Petrof I, Sherman SM. Functional significance of synaptic terminal size in glutamatergic sensory pathways in thalamus and cortex. J Physiol 2013; 591:3125-31. [PMID: 23359668 DOI: 10.1113/jphysiol.2012.247619] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Glutamatergic pathways are a major information-carrying and -processing network of inputs in the brain. There is considerable evidence suggesting that glutamatergic pathways do not represent a homogeneous group and that they can be segregated into at least two broad categories. Class 1 glutamatergic inputs, which are suggested to be the main information carriers, are characterized by a number of unique synaptic and anatomical features, such as the large synaptic boutons with which they often terminate. On the other hand, Class 2 inputs, which are thought to play a modulatory role, are associated, amongst other features, with exclusively small terminal boutons. Here we summarize and briefly discuss these two classes of glutamatergic input and how their unique features, including their terminal bouton size and anatomy, are related to their suggested function.
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Affiliation(s)
- Iraklis Petrof
- Department of Neurobiology, The University of Chicago, Chicago, IL 60637, USA
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T-type calcium channels consolidate tonic action potential output of thalamic neurons to neocortex. J Neurosci 2012; 32:12228-36. [PMID: 22933804 DOI: 10.1523/jneurosci.1362-12.2012] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The thalamic output during different behavioral states is strictly controlled by the firing modes of thalamocortical neurons. During sleep, their hyperpolarized membrane potential allows activation of the T-type calcium channels, promoting rhythmic high-frequency burst firing that reduces sensory information transfer. In contrast, in the waking state thalamic neurons mostly exhibit action potentials at low frequency (i.e., tonic firing), enabling the reliable transfer of incoming sensory inputs to cortex. Because of their nearly complete inactivation at the depolarized potentials that are experienced during the wake state, T-channels are not believed to modulate tonic action potential discharges. Here, we demonstrate using mice brain slices that activation of T-channels in thalamocortical neurons maintained in the depolarized/wake-like state is critical for the reliable expression of tonic firing, securing their excitability over changes in membrane potential that occur in the depolarized state. Our results establish a novel mechanism for the integration of sensory information by thalamocortical neurons and point to an unexpected role for T-channels in the early stage of information processing.
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Rewiring of afferent fibers in the somatosensory thalamus of mice caused by peripheral sensory nerve transection. J Neurosci 2012; 32:6917-30. [PMID: 22593060 DOI: 10.1523/jneurosci.5008-11.2012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The remodeling of neural circuitry and changes in synaptic efficacy after peripheral sensory nerve injury are considered the basis for functional reorganization in the brain, including changes in receptive fields. However, when or how the remodeling occurs is largely unknown. Here we show the rapid rewiring of afferent fibers in the mature ventral posteromedial thalamic nucleus of mice after transection of the peripheral whisker sensory nerve, using the whole-cell voltage-clamp technique. Transection induced the recruitment of afferent fibers to a thalamic relay neuron within 5-6 d of injury. The rewiring was pathway specific, but not sensory experience dependent or peripheral nerve activity dependent. The newly recruited fibers mediated small EPSCs, and postsynaptic GluA2-containing AMPA receptors were selectively upregulated at the new synapses. This rapid and pathway-specific remodeling of thalamic circuitry may be an initial step in the massive axonal reorganization at supraspinal levels, which occurs months or years after peripheral sensory nerve injury.
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Favero M, Varghese G, Castro-Alamancos MA. The state of somatosensory cortex during neuromodulation. J Neurophysiol 2012; 108:1010-24. [PMID: 22623484 DOI: 10.1152/jn.00256.2012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During behavioral quiescence, such as slow-wave sleep and anesthesia, the neocortex is in a deactivated state characterized by the presence of slow oscillations. During arousal, slow oscillations are absent and the neocortex is in an activated state that greatly impacts information processing. Neuromodulators acting in neocortex are believed to mediate these state changes, but the mechanisms are poorly understood. We investigated the actions of noradrenergic and cholinergic activation on slow oscillations, cellular excitability, and synaptic inputs in thalamocortical slices of somatosensory cortex. The results show that neuromodulation abolishes slow oscillations, dampens the excitability of principal cells, and rebalances excitatory and inhibitory synaptic inputs in thalamocortical-recipient layers IV-III. Sensory cortex is much more selective about the inputs that can drive it. The source of neuromodulation is critically important in determining this selectivity. Cholinergic activation suppresses the excitatory and inhibitory conductances driven by thalamocortical and intracortical inputs. Noradrenergic activation suppresses the excitatory conductance driven by intracortical inputs but not by thalamocortical inputs and enhances the inhibitory conductance driven by thalamocortical inputs but not by intracortical inputs. Thus noradrenergic activation emphasizes thalamocortical (sensory) inputs relative to intracortical inputs, while cholinergic activation suppresses both.
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Affiliation(s)
- Morgana Favero
- Dept. of Neurobiology and Anatomy, Drexel Univ. College of Medicine, Philadelphia, PA 19129, USA
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Ego-Stengel V, Le Cam J, Shulz DE. Coding of apparent motion in the thalamic nucleus of the rat vibrissal somatosensory system. J Neurosci 2012; 32:3339-51. [PMID: 22399756 PMCID: PMC6621038 DOI: 10.1523/jneurosci.3890-11.2012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 12/16/2011] [Accepted: 12/30/2011] [Indexed: 11/21/2022] Open
Abstract
While exploring objects, rats make multiple contacts using their whiskers, thereby generating complex patterns of sensory information. The cerebral structures that process this information in the somatosensory system show discrete patterns of anatomically distinct units, each corresponding to one whisker. Moreover, the feedforward and feedback connections are remarkably topographic, with little cross-whisker divergence before reaching the cortical network. Despite this parallel design, information processing from several whiskers has been reported in subcortical nuclei. Here, we explored whether sensory neurons in the ventral posterior medial nucleus (VPM) of the thalamus encode emergent properties of complex multiwhisker stimulations. Using a 24-whisker stimulator, we tested the responses of VPM neurons to sequences of caudal deflections that generated an apparent motion in eight different directions across the whiskerpad. Overall, 45% of neurons exhibited an evoked increase in firing rate significantly selective to the direction of apparent motion of the global stimulus. Periods of suppression of firing rate were often observed, but were generally not selective. Global motion selectivity of VPM neurons could occur regardless of the extent and spatial organization of their receptive fields, and of their selectivity for the direction of motion of their principal whisker. To investigate whether the global selectivity could be due to corticothalamic feedback connections, we inactivated the barrel cortex while repeating the stimulation protocol. For most VPM neurons, the direction selectivity decreased but was still present. These results suggest that nonlinear processing of stimuli from different whiskers emerges in subcortical nuclei and is amplified by the corticofugal feedback.
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Affiliation(s)
- Valérie Ego-Stengel
- Unité de Neuroscience, Information et Complexité, UPR CNRS 3293, Centre National de la Recherche Scientifique, 91198 Gif-sur-Yvette, France.
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Pirttimaki TM, Parri HR. Glutamatergic input-output properties of thalamic astrocytes. Neuroscience 2012; 205:18-28. [PMID: 22233780 PMCID: PMC3314995 DOI: 10.1016/j.neuroscience.2011.12.049] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 12/02/2011] [Accepted: 12/22/2011] [Indexed: 11/10/2022]
Abstract
Astrocytes in the somatosensory ventrobasal (VB) thalamus of rats respond to glutamatergic synaptic input with metabotropic glutamate receptor (mGluR) mediated intracellular calcium ([Ca2+]i) elevations. Astrocytes in the VB thalamus also release the gliotransmitter (GT) glutamate in a Ca2+-dependent manner. The tripartite synapse hypothesis posits that astrocytic [Ca2+]i elevations resulting from synaptic input releases gliotransmitters that then feedback to modify the synapse. Understanding the dynamics of this process and the conditions under which it occurs are therefore important steps in elucidating the potential roles and impact of GT release in particular brain activities. In this study, we investigated the relationship between VB thalamus afferent synaptic input and astrocytic glutamate release by recording N-methyl-d-aspartate (NMDA) receptor-mediated slow inward currents (SICs) elicited in neighboring neurons. We found that Lemniscal or cortical afferent stimulation, which can elicit astrocytic [Ca2+]i elevations, do not typically result in the generation of SICs in thalamocortical (TC) neurons. Rather, we find that the spontaneous emergence of SICs is largely resistant to acute afferent input. The frequency of SICs, however, is correlated to long-lasting afferent activity. In contrast to short-term stimulus-evoked GT release effects reported in other brain areas, astrocytes in the VB thalamus do not express a straightforward input–output relationship for SIC generation but exhibit integrative characteristics.
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Affiliation(s)
- T M Pirttimaki
- School of Life and Health Sciences, Aston University, Birmingham B4 7ET, UK
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Rabang CF, Bartlett EL. A computational model of cellular mechanisms of temporal coding in the medial geniculate body (MGB). PLoS One 2011; 6:e29375. [PMID: 22195049 PMCID: PMC3241713 DOI: 10.1371/journal.pone.0029375] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 11/28/2011] [Indexed: 12/04/2022] Open
Abstract
Acoustic stimuli are often represented in the early auditory pathway as patterns of neural activity synchronized to time-varying features. This phase-locking predominates until the level of the medial geniculate body (MGB), where previous studies have identified two main, largely segregated response types: Stimulus-synchronized responses faithfully preserve the temporal coding from its afferent inputs, and Non-synchronized responses, which are not phase locked to the inputs, represent changes in temporal modulation by a rate code. The cellular mechanisms underlying this transformation from phase-locked to rate code are not well understood. We use a computational model of a MGB thalamocortical neuron to test the hypothesis that these response classes arise from inferior colliculus (IC) excitatory afferents with divergent properties similar to those observed in brain slice studies. Large-conductance inputs exhibiting synaptic depression preserved input synchrony as short as 12.5 ms interclick intervals, while maintaining low firing rates and low-pass filtering responses. By contrast, small-conductance inputs with Mixed plasticity (depression of AMPA-receptor component and facilitation of NMDA-receptor component) desynchronized afferent inputs, generated a click-rate dependent increase in firing rate, and high-pass filtered the inputs. Synaptic inputs with facilitation often permitted band-pass synchrony along with band-pass rate tuning. These responses could be tuned by changes in membrane potential, strength of the NMDA component, and characteristics of synaptic plasticity. These results demonstrate how the same synchronized input spike trains from the inferior colliculus can be transformed into different representations of temporal modulation by divergent synaptic properties.
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Affiliation(s)
- Cal F. Rabang
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
| | - Edward L. Bartlett
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail:
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Sun YG, Beierlein M. Receptor saturation controls short-term synaptic plasticity at corticothalamic synapses. J Neurophysiol 2011; 105:2319-29. [DOI: 10.1152/jn.00942.2010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Glutamatergic synapses of layer 6 corticothalamic (CT) neurons form a major excitatory input onto thalamic relay cells, allowing neocortex to continuously control sensory information processing in thalamic circuits. CT synapses display both short- and long-term forms of use-dependent synaptic enhancement, mediated at least in part by increases in the probability of transmitter release. At some synapses, such increases in release probability are accompanied by a higher degree of multivesicular release (MVR) and larger glutamate transients at individual release sites, resulting in the saturation of postsynaptic receptors. The extent to which MVR and postsynaptic saturation interact and control short-term plasticity at CT synapses is not known. Here we examined two distinct presynaptic forms of short-term enhancement, facilitation and augmentation, at CT synapses contacting relay neurons in the ventrobasal nucleus of the mouse thalamus. We found that, in the presence of the low-affinity antagonist γ-d-glutamylglycine, to relieve postsynaptic dl-α-amino-3-hydroxy-5-methylisox azole-propionic acid (AMPA) receptor saturation, the magnitude of facilitation and augmentation increased. Whereas receptor saturation was prominent for both AMPA and N-methyl-d-aspartate receptors, desensitization of AMPA receptors did not significantly alter short-term plasticity. Our results suggest that at CT synapses the activity-dependent increase in synaptic strength is controlled by postsynaptic receptor saturation.
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Affiliation(s)
- Yan-Gang Sun
- Department of Neurobiology and Anatomy, University of Texas Medical School, Houston, Texas
| | - Michael Beierlein
- Department of Neurobiology and Anatomy, University of Texas Medical School, Houston, Texas
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Bezdudnaya T, Castro-Alamancos MA. Superior colliculus cells sensitive to active touch and texture during whisking. J Neurophysiol 2011; 106:332-46. [PMID: 21525369 DOI: 10.1152/jn.00072.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Rats sense the environment through rhythmic vibrissa protractions, called active whisking, which can be simulated in anesthetized rats by electrically stimulating the facial motor nerve. Using this method, we investigated barrel cortex field potential and superior colliculus single-unit responses during passive touch, whisking movement, active touch, and texture discrimination. Similar to passive touch, whisking movement is signaled during the onset of the whisker protraction by short-latency responses in barrel cortex that drive corticotectal responses in superior colliculus, and all these responses show robust adaptation with increases in whisking frequency. Active touch and texture are signaled by longer latency responses, first in superior colliculus during the rising phase of the protraction, likely driven by trigeminotectal inputs, and later in barrel cortex by the falling phase of the protraction. Thus, superior colliculus is part of a broader vibrissa neural network that can decode whisking movement, active touch, and texture.
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Affiliation(s)
- Tatiana Bezdudnaya
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, USA
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