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Sherman SM, Usrey WM. Transthalamic Pathways for Cortical Function. J Neurosci 2024; 44:e0909242024. [PMID: 39197951 PMCID: PMC11358609 DOI: 10.1523/jneurosci.0909-24.2024] [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: 05/14/2024] [Revised: 07/06/2024] [Accepted: 07/18/2024] [Indexed: 09/01/2024] Open
Abstract
The cerebral cortex contains multiple, distinct areas that individually perform specific computations. A particular strength of the cortex is the communication of signals between cortical areas that allows the outputs of these compartmentalized computations to influence and build on each other, thereby dramatically increasing the processing power of the cortex and its role in sensation, action, and cognition. Determining how the cortex communicates signals between individual areas is, therefore, critical for understanding cortical function. Historically, corticocortical communication was thought to occur exclusively by direct anatomical connections between areas that often sequentially linked cortical areas in a hierarchical fashion. More recently, anatomical, physiological, and behavioral evidence is accumulating indicating a role for the higher-order thalamus in corticocortical communication. Specifically, the transthalamic pathway involves projections from one area of the cortex to neurons in the higher-order thalamus that, in turn, project to another area of the cortex. Here, we consider the evidence for and implications of having two routes for corticocortical communication with an emphasis on unique processing available in the transthalamic pathway and the consequences of disorders and diseases that affect transthalamic communication.
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Affiliation(s)
- S Murray Sherman
- Department of Neurobiology, University of Chicago, Chicago, Illinois 60637
| | - W Martin Usrey
- Center for Neuroscience, University of California, Davis, California 95618
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2
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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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3
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Wang J, Azimi H, Zhao Y, Kaeser M, Vaca Sánchez P, Vazquez-Guardado A, Rogers JA, Harvey M, Rainer G. Optogenetic activation of visual thalamus generates artificial visual percepts. eLife 2023; 12:e90431. [PMID: 37791662 PMCID: PMC10593406 DOI: 10.7554/elife.90431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 10/03/2023] [Indexed: 10/05/2023] Open
Abstract
The lateral geniculate nucleus (LGN), a retinotopic relay center where visual inputs from the retina are processed and relayed to the visual cortex, has been proposed as a potential target for artificial vision. At present, it is unknown whether optogenetic LGN stimulation is sufficient to elicit behaviorally relevant percepts, and the properties of LGN neural responses relevant for artificial vision have not been thoroughly characterized. Here, we demonstrate that tree shrews pretrained on a visual detection task can detect optogenetic LGN activation using an AAV2-CamKIIα-ChR2 construct and readily generalize from visual to optogenetic detection. Simultaneous recordings of LGN spiking activity and primary visual cortex (V1) local field potentials (LFPs) during optogenetic LGN stimulation show that LGN neurons reliably follow optogenetic stimulation at frequencies up to 60 Hz and uncovered a striking phase locking between the V1 LFP and the evoked spiking activity in LGN. These phase relationships were maintained over a broad range of LGN stimulation frequencies, up to 80 Hz, with spike field coherence values favoring higher frequencies, indicating the ability to relay temporally precise information to V1 using light activation of the LGN. Finally, V1 LFP responses showed sensitivity values to LGN optogenetic activation that were similar to the animal's behavioral performance. Taken together, our findings confirm the LGN as a potential target for visual prosthetics in a highly visual mammal closely related to primates.
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Affiliation(s)
- Jing Wang
- Department of Medicine, University of FribourgFribourgSwitzerland
- Department of Neurobiology, School of Basic Medical Sciences, Nanjing Medical UniversityNanjingChina
| | - Hamid Azimi
- Department of Medicine, University of FribourgFribourgSwitzerland
| | - Yilei Zhao
- Department of Medicine, University of FribourgFribourgSwitzerland
| | - Melanie Kaeser
- Department of Medicine, University of FribourgFribourgSwitzerland
| | | | | | - John A Rogers
- Querrey Simpson Institute for Bioelectronics, Northwestern UniversityEvanstonUnited States
| | - Michael Harvey
- Department of Medicine, University of FribourgFribourgSwitzerland
| | - Gregor Rainer
- Department of Medicine, University of FribourgFribourgSwitzerland
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4
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Mease RA, Gonzalez AJ. Corticothalamic Pathways From Layer 5: Emerging Roles in Computation and Pathology. Front Neural Circuits 2021; 15:730211. [PMID: 34566583 PMCID: PMC8458899 DOI: 10.3389/fncir.2021.730211] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 08/10/2021] [Indexed: 11/29/2022] Open
Abstract
Large portions of the thalamus receive strong driving input from cortical layer 5 (L5) neurons but the role of this important pathway in cortical and thalamic computations is not well understood. L5-recipient "higher-order" thalamic regions participate in cortico-thalamo-cortical (CTC) circuits that are increasingly recognized to be (1) anatomically and functionally distinct from better-studied "first-order" CTC networks, and (2) integral to cortical activity related to learning and perception. Additionally, studies are beginning to elucidate the clinical relevance of these networks, as dysfunction across these pathways have been implicated in several pathological states. In this review, we highlight recent advances in understanding L5 CTC networks across sensory modalities and brain regions, particularly studies leveraging cell-type-specific tools that allow precise experimental access to L5 CTC circuits. We aim to provide a focused and accessible summary of the anatomical, physiological, and computational properties of L5-originating CTC networks, and outline their underappreciated contribution in pathology. We particularly seek to connect single-neuron and synaptic properties to network (dys)function and emerging theories of cortical computation, and highlight information processing in L5 CTC networks as a promising focus for computational studies.
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Affiliation(s)
- Rebecca A. Mease
- Institute of Physiology and Pathophysiology, Medical Biophysics, Heidelberg University, Heidelberg, Germany
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5
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Desai NV, Varela C. Distinct burst properties contribute to the functional diversity of thalamic nuclei. J Comp Neurol 2021; 529:3726-3750. [PMID: 33723858 PMCID: PMC8440663 DOI: 10.1002/cne.25141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 03/10/2021] [Accepted: 03/12/2021] [Indexed: 12/21/2022]
Abstract
Thalamic neurons fire spikes in two modes, burst and tonic. The function of burst firing is unclear, but the evidence suggests that bursts are more effective at activating cortical cells, and that postinhibition rebound bursting contributes to thalamocortical oscillations during sleep. Bursts are considered stereotyped signals; however, there is limited evidence regarding how burst properties compare across thalamic nuclei of different functional or anatomical organization. Here, we used whole-cell patch clamp recordings and compartmental modeling to investigate the properties of bursts in six sensory thalamic nuclei, to study the mechanisms that can lead to different burst properties, and to assess the implications of different burst properties for thalamocortical transmission and oscillatory functions. We found that bursts in higher-order cells on average had higher number of spikes and longer latency to the first spike. Additionally, burst features in first-order neurons were determined by sensory modality. Shifting the voltage-dependence and density of the T-channel conductance in a compartmental model replicates the burst properties from the intracellular recordings, pointing to molecular mechanisms that can generate burst diversity. Furthermore, the model predicts that bursts with higher number of spikes will drastically reduce the effectiveness of thalamocortical transmission. In addition, the latency to burst limited the rebound oscillatory frequency in modeled cells. These results demonstrate that burst properties vary according to the thalamocortical hierarchy and with sensory modality. The findings imply that, while in burst mode, thalamocortical transmission and firing frequency will be determined by the number of spikes and latency to burst.
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Affiliation(s)
- Nidhi Vasant Desai
- Psychology Department, Jupiter Life Sciences Initiative, Florida Atlantic University, Boca Raton, Florida, USA
| | - Carmen Varela
- Psychology Department, Jupiter Life Sciences Initiative, Florida Atlantic University, Boca Raton, Florida, USA
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Role of T-type Calcium Channels in Generating Hyperexcitatory Behaviors during Emergence from Sevoflurane Anesthesia in Neonatal Rats. Neurosci Bull 2020; 36:519-529. [PMID: 31953800 DOI: 10.1007/s12264-019-00461-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 11/06/2019] [Indexed: 01/27/2023] Open
Abstract
In the current study, we sought to investigate whether T-type Ca2+ channels (TCCs) in the brain are involved in generating post-anesthetic hyperexcitatory behaviors (PAHBs). We found that younger rat pups (postnatal days 9-11) had a higher incidence of PAHBs and higher PAHB scores than older pups (postnatal days 16-18) during emergence from sevoflurane anesthesia. The power spectrum of the theta oscillations (4 Hz-8 Hz) in the prefrontal cortex was significantly enhanced in younger pups when PAHBs occurred, while there were no significant changes in older pups. Both the power of theta oscillations and the level of PAHBs were significantly reduced by the administration of TCC inhibitors. Moreover, the sensitivity of TCCs in the medial dorsal thalamic nucleus to sevoflurane was found to increase with age by investigating the kinetic properties of TCCs in vitro. TCCs were activated by potentiated GABAergic depolarization with a sub-anesthetic dose of sevoflurane (1%). These data suggest that (1) TCCs in the brain contribute to the generation of PAHBs and the concomitant electroencephalographic changes; (2) the stronger inhibitory effect of sevoflurane contributes to the lack of PAHBs in older rats; and (3) the contribution of TCCs to PAHBs is not mediated by a direct effect of sevoflurane on TCCs.
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Whyland KL, Slusarczyk AS, Bickford ME. GABAergic cell types in the superficial layers of the mouse superior colliculus. J Comp Neurol 2019; 528:308-320. [PMID: 31396959 DOI: 10.1002/cne.24754] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 08/02/2019] [Accepted: 08/02/2019] [Indexed: 12/20/2022]
Abstract
To begin to unravel the complexities of GABAergic circuits in the superior colliculus (SC), we utilized mouse lines that express green fluorescent protein (GFP) in cells that contain the 67 kDa isoform of glutamic acid decarboxylase (GAD67-GFP), or Cre-recombinase in cells that contain glutamic acid decarboxylase (GAD; GAD2-cre). We used Cre-dependent virus injections in GAD2-Cre mice and tracer injections in GAD67-GFP mice, as well as immunocytochemical staining for gamma amino butyric acid (GABA) and parvalbumin (PV) to characterize GABAergic cells that project to the pretectum (PT), ventral lateral geniculate nucleus (vLGN) or parabigeminal nucleus (PBG), and interneurons in the stratum griseum superficiale (SGS) that do not project outside the SC. We found that approximately 30% of SGS neurons in the mouse are GABAergic. Of these GABAergic neurons, we identified three categories of potential interneurons in the GAD67-GFP line (GABA+GFP ~45%, GABA+GFP + PV ~15%, and GABA+PV ~10%). GABAergic cells that did not contain GFP or PV were identified as potential projection neurons (GABA only ~30%). We found that GABAergic neurons that project to the PBG are primarily located in the SGS and exhibit narrow field vertical, stellate, and horizontal dendritic morphologies, while GABAergic neurons that project to the PT and vLGN are primarily located in layers ventral to the SGS. In addition, we examined GABA and GAD67-containing elements of the mouse SGS using electron microscopy to further delineate the relationship between GABAergic circuits and retinotectal input. Approximately 30% of retinotectal synaptic targets are the presynaptic dendrites of GABAergic interneurons, and GAD67-GFP interneurons are a source of these presynaptic dendrites.
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Affiliation(s)
- Kyle L Whyland
- Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky
| | | | - Martha E Bickford
- Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky
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Kaskie RE, Graziano B, Ferrarelli F. Topographic deficits in sleep spindle density and duration point to frontal thalamo-cortical dysfunctions in first-episode psychosis. J Psychiatr Res 2019; 113:39-44. [PMID: 30878791 DOI: 10.1016/j.jpsychires.2019.03.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 03/07/2019] [Accepted: 03/07/2019] [Indexed: 10/27/2022]
Abstract
Sleep spindles are NREM sleep EEG oscillations, which are initiated within the thalamus and are regulated by thalamo-cortical circuits. Previous work from our and other research groups has shown marked spindle deficits in patients with schizophrenia (SCZ). However, the presence of spindle impairments at illness onset, including which parameters are most affected, their topographic characteristics, and their relationships with clinical symptoms have yet to be characterized. In this study we performed sleep high density (hd)-EEG recordings in twenty-seven first-episode psychosis (FEP) patients and twenty-three healthy controls (HC). Several spindle parameters-amplitude, duration, and density-were calculated and compared across groups. FEP patients showed reduced spindle duration and density, but not in spindle amplitude relative to HC. These spindles reductions were localized in a frontal area and predicted the severity of FEP patients' negative symptoms. Altogether, these findings indicate that spindle deficits are present at the beginning of psychosis, contribute to clinical symptomatology, and point to frontal thalamo-cortical dysfunctions, thus providing a potential treatment target for early interventions in SCZ and related psychotic disorders.
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The Augmentation of Retinogeniculate Communication during Thalamic Burst Mode. J Neurosci 2019; 39:5697-5710. [PMID: 31109958 DOI: 10.1523/jneurosci.2320-18.2019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 05/09/2019] [Accepted: 05/10/2019] [Indexed: 11/21/2022] Open
Abstract
Retinal signals are transmitted to cortex via neurons in the lateral geniculate nucleus (LGN), where they are processed in burst or tonic response mode. Burst mode occurs when LGN neurons are sufficiently hyperpolarized for T-type Ca2+ channels to deinactivate, allowing them to open in response to depolarization, which can trigger a high-frequency sequence of Na+-based spikes (i.e., burst). In contrast, T-type channels are inactivated during tonic mode and do not contribute to spiking. Although burst mode is commonly associated with sleep and the disruption of retinogeniculate communication, bursts can also be triggered by visual stimulation, thereby transforming the retinal signals relayed to the cortex. To determine how burst mode affects retinogeniculate communication, we made recordings from monosynaptically connected retinal ganglion cells and LGN neurons in male/female cats during visual stimulation. Our results reveal a robust augmentation of retinal signals within the LGN during burst mode. Specifically, retinal spikes were more effective and often triggered multiple LGN spikes during periods likely to have increased T-type Ca2+ channel activity. Consistent with the biophysical properties of T-type Ca2+ channels, analysis revealed that effect magnitude was correlated with the duration of the preceding thalamic interspike interval and occurred even in the absence of classically defined bursts. Importantly, the augmentation of geniculate responses to retinal input was not associated with a degradation of visual signals. Together, these results indicate a graded nature of response mode and suggest that, under certain conditions, bursts facilitate the transmission of visual information to the cortex by amplifying retinal signals.SIGNIFICANCE STATEMENT The thalamus is the gateway for retinal information traveling to the cortex. The lateral geniculate nucleus, like all thalamic nuclei, has two classically defined categories of spikes-tonic and burst-that differ in their underlying cellular mechanisms. Here we compare retinogeniculate communication during burst and tonic response modes. Our results show that retinogeniculate communication is enhanced during burst mode and visually evoked thalamic bursts, thereby augmenting retinal signals transmitted to cortex. Further, our results demonstrate that the influence of burst mode on retinogeniculate communication is graded and can be measured even in the absence of classically defined thalamic bursts.
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10
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Experimentally-constrained biophysical models of tonic and burst firing modes in thalamocortical neurons. PLoS Comput Biol 2019; 15:e1006753. [PMID: 31095552 PMCID: PMC6541309 DOI: 10.1371/journal.pcbi.1006753] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 05/29/2019] [Accepted: 04/10/2019] [Indexed: 01/12/2023] Open
Abstract
Somatosensory thalamocortical (TC) neurons from the ventrobasal (VB) thalamus are central components in the flow of sensory information between the periphery and the cerebral cortex, and participate in the dynamic regulation of thalamocortical states including wakefulness and sleep. This property is reflected at the cellular level by the ability to generate action potentials in two distinct firing modes, called tonic firing and low-threshold bursting. Although the general properties of TC neurons are known, we still lack a detailed characterization of their morphological and electrical properties in the VB thalamus. The aim of this study was to build biophysically-detailed models of VB TC neurons explicitly constrained with experimental data from rats. We recorded the electrical activity of VB neurons (N = 49) and reconstructed morphologies in 3D (N = 50) by applying standardized protocols. After identifying distinct electrical types, we used a multi-objective optimization to fit single neuron electrical models (e-models), which yielded multiple solutions consistent with the experimental data. The models were tested for generalization using electrical stimuli and neuron morphologies not used during fitting. A local sensitivity analysis revealed that the e-models are robust to small parameter changes and that all the parameters were constrained by one or more features. The e-models, when tested in combination with different morphologies, showed that the electrical behavior is substantially preserved when changing dendritic structure and that the e-models were not overfit to a specific morphology. The models and their analysis show that automatic parameter search can be applied to capture complex firing behavior, such as co-existence of tonic firing and low-threshold bursting over a wide range of parameter sets and in combination with different neuron morphologies. Thalamocortical neurons are one of the main components of the thalamocortical system, which is implicated in key functions including sensory transmission and the transition between brain states. These functions are reflected at the cellular level by the ability to generate action potentials in two distinct modes, called burst and tonic firing. Biophysically-detailed computational modeling of these cells can provide a tool to understand the role of these neurons within thalamocortical circuitry. We started by collecting single cell experimental data by applying standardized experimental procedures in brain slices of the rat. Prior work has demonstrated that biological constraints can be integrated using multi-objective optimization to build biologically realistic models of neurons. Here, we employed similar techniques, but extended them to capture the multiple firing modes of thalamic neurons. We compared the model results with additional experimental data, test their generalization and quantitatively reject those that deviated significantly from the experimental variability. These models can be readily integrated in a data-driven pipeline to reconstruct and simulate circuit activity in the thalamocortical system.
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Lüttjohann A, Pape HC. Regional specificity of cortico-thalamic coupling strength and directionality during waxing and waning of spike and wave discharges. Sci Rep 2019; 9:2100. [PMID: 30765744 PMCID: PMC6375974 DOI: 10.1038/s41598-018-37985-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 12/14/2018] [Indexed: 11/24/2022] Open
Abstract
Spike-wave discharges (SWDs) on the EEG during absence epilepsy are waxing and waning stages of corticothalamic hypersynchrony. While the somatosensory cortex contains an epileptic focus, the role of thalamic nuclei in SWD generation is debated. Here we assess the contribution of distinct thalamic nuclei through multiple-site unit recordings in a genetic rat model of absence epilepsy and cross-correlation analysis, revealing coupling strength and directionality of neuronal activity at high temporal resolution. Corticothalamic coupling increased and decreased during waxing and waning of SWD, respectively. A cortical drive on either sensory or higher order thalamic nuclei distinguished between onset and offset of SWD, respectively. Intrathalamic coupling steadily increased during maintained SWD activity, peaked at SWD offset, and subsequently displayed a sharp decline to baseline. The peak in intrathalamic coupling coincided with a sharp increase in coupling strength between reticular thalamic nucleus and somatosensory cortex. This increased influence of the inhibitory reticular thalamic nucleus is suggested to serve as a break for SWD activity. Overall, the data extend the cortical focus theory of absence epilepsy by identifying a regionally specific cortical lead over distinct thalamic nuclei, particularly also during waning of generalized epileptic discharges, thereby revealing a potential window and location for intervention.
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Affiliation(s)
- Annika Lüttjohann
- Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany.
| | - Hans-Christian Pape
- Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany.
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12
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Zimmerman EC, Grace AA. Prefrontal cortex modulates firing pattern in the nucleus reuniens of the midline thalamus via distinct corticothalamic pathways. Eur J Neurosci 2018; 48:3255-3272. [PMID: 30107061 PMCID: PMC6237082 DOI: 10.1111/ejn.14111] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 07/12/2018] [Accepted: 07/31/2018] [Indexed: 02/06/2023]
Abstract
The thalamus has long been recognized for its role in relaying sensory information from the periphery, a function accomplished by its "first-order" nuclei. However, a second category of thalamic nuclei, termed "higher-order" nuclei, have been shown instead to mediate communication between cortical areas. The nucleus reuniens of the midline thalamus (RE) is a higher-order nucleus known to act as a conduit of reciprocal communication between the medial prefrontal cortex (mPFC) and hippocampus. While anatomical and behavioural studies of RE are numerous, circuit-based electrophysiological studies, particularly those examining the impact of cortical input and the thalamic reticular nucleus (TRN) on RE neuron firing, are sparse. To characterize RE neuron firing properties and dissect the circuit dynamics of the infralimbic subdivision of the mPFC (ilPFC), the TRN and RE, we used in vivo, extracellular, single-unit recordings in male Sprague Dawley rats and manipulated neural activity using targeted pharmacological manipulations, electrical stimulation and a projection-specific implementation of designer receptors exclusively activated by designer drugs (DREADDs). We show that ilPFC inhibition reduces multiple burst firing parameters in RE, whereas ilPFC stimulation drives burst firing and dampens tonic firing. In addition, TRN inhibition reduces the number of spontaneously active neurons in RE. Finally, inhibition of ilPFC terminals in RE selectively enhances a subset of burst firing parameters. These findings demonstrate that ilPFC input, both via direct projections and via the TRN, can modulate RE neuron firing pattern in nuanced and complex ways. They also highlight the ilPFC-TRN-RE circuit as a likely critical component of prefrontal-hippocampal interactions.
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Affiliation(s)
- Eric C Zimmerman
- Departments of Neuroscience, Psychiatry, and Psychology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Anthony A Grace
- Departments of Neuroscience, Psychiatry, and Psychology, University of Pittsburgh, Pittsburgh, Pennsylvania
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Abstract
Comparative studies have greatly contributed to our understanding of the organization and function of visual pathways of the brain, including that of humans. This comparative approach is a particularly useful tactic for studying the pulvinar nucleus, an enigmatic structure which comprises the largest territory of the human thalamus. This review focuses on the regions of the mouse pulvinar that receive input from the superior colliculus, and highlights similarities of the tectorecipient pulvinar identified across species. Open questions are discussed, as well as the potential contributions of the mouse model for endeavors to elucidate the function of the pulvinar nucleus.
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14
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Petry HM, Bickford ME. The Second Visual System of The Tree Shrew. J Comp Neurol 2018; 527:679-693. [PMID: 29446088 DOI: 10.1002/cne.24413] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Revised: 02/01/2018] [Accepted: 02/06/2018] [Indexed: 12/28/2022]
Abstract
This review provides a historical account of the discovery of secondary visual pathways (from retina to the superior colliculus to the dorsal thalamus and extrastriate cortex), and Vivien Casagrande's pioneering studies of this system using the tree shrew as a model. Subsequent studies of visual pathways in the tree shrew are also reviewed, beginning with a description of the organization and central projections of the tree shrew retina. The organization and connectivity of second visual system components that include the retino-recipient superior colliculus, tecto-recipient pulvinar nucleus and its projections, and the tecto-recipient dorsal lateral geniculate nucleus and its projections are detailed. Potential functions of the second visual system are discussed in the context of this work and in the context of the behavioral studies that initially inspired the secondary visual system concept.
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Affiliation(s)
- Heywood M Petry
- Department of Psychological and Brain Sciences, University of Louisville, Louisville, Kentucky
| | - Martha E Bickford
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky
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15
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Schweser F, Raffaini Duarte Martins AL, Hagemeier J, Lin F, Hanspach J, Weinstock-Guttman B, Hametner S, Bergsland N, Dwyer MG, Zivadinov R. Mapping of thalamic magnetic susceptibility in multiple sclerosis indicates decreasing iron with disease duration: A proposed mechanistic relationship between inflammation and oligodendrocyte vitality. Neuroimage 2018; 167:438-452. [PMID: 29097315 PMCID: PMC5845810 DOI: 10.1016/j.neuroimage.2017.10.063] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 10/24/2017] [Accepted: 10/27/2017] [Indexed: 12/13/2022] Open
Abstract
Recent advances in susceptibility MRI have dramatically improved the visualization of deep gray matter brain regions and the quantification of their magnetic properties in vivo, providing a novel tool to study the poorly understood iron homeostasis in the human brain. In this study, we used an advanced combination of the recent quantitative susceptibility mapping technique with dedicated analysis methods to study intra-thalamic tissue alterations in patients with clinically isolated syndrome (CIS) and multiple sclerosis (MS). Thalamic pathology is one of the earliest hallmarks of MS and has been shown to correlate with cognitive dysfunction and fatigue, but the mechanisms underlying the thalamic pathology are poorly understood. We enrolled a total of 120 patients, 40 with CIS, 40 with Relapsing Remitting MS (RRMS), and 40 with Secondary Progressive MS (SPMS). For each of the three patient groups, we recruited 40 controls, group matched for age- and sex (120 total). We acquired quantitative susceptibility maps using a single-echo gradient echo MRI pulse sequence at 3 T. Group differences were studied by voxel-based analysis as well as with a custom thalamus atlas. We used threshold-free cluster enhancement (TFCE) and multiple regression analyses, respectively. We found significantly reduced magnetic susceptibility compared to controls in focal thalamic subregions of patients with RRMS (whole thalamus excluding the pulvinar nucleus) and SPMS (primarily pulvinar nucleus), but not in patients with CIS. Susceptibility reduction was significantly associated with disease duration in the pulvinar, the left lateral nuclear region, and the global thalamus. Susceptibility reduction indicates a decrease in tissue iron concentration suggesting an involvement of chronic microglia activation in the depletion of iron from oligodendrocytes in this central and integrative brain region. Not necessarily specific to MS, inflammation-mediated iron release may lead to a vicious circle that reduces the protection of axons and neuronal repair.
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Affiliation(s)
- Ferdinand Schweser
- Buffalo Neuroimaging Analysis Center, Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, USA; Center for Biomedical Imaging, Clinical and Translational Science Institute, University at Buffalo, The State University of New York, Buffalo, NY, USA.
| | - Ana Luiza Raffaini Duarte Martins
- Buffalo Neuroimaging Analysis Center, Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Jesper Hagemeier
- Buffalo Neuroimaging Analysis Center, Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Fuchun Lin
- Buffalo Neuroimaging Analysis Center, Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Jannis Hanspach
- Buffalo Neuroimaging Analysis Center, Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, USA; Institute of Radiology, University Hospital Erlangen, Erlangen, Germany
| | - Bianca Weinstock-Guttman
- Jacobs Multiple Sclerosis Center, Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Simon Hametner
- Department of Neuroimmunology, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Niels Bergsland
- Buffalo Neuroimaging Analysis Center, Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Michael G Dwyer
- Buffalo Neuroimaging Analysis Center, Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Robert Zivadinov
- Buffalo Neuroimaging Analysis Center, Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, USA; Center for Biomedical Imaging, Clinical and Translational Science Institute, University at Buffalo, The State University of New York, Buffalo, NY, USA
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16
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Towards building a more complex view of the lateral geniculate nucleus: Recent advances in understanding its role. Prog Neurobiol 2017. [DOI: 10.1016/j.pneurobio.2017.06.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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17
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Fogerson PM, Huguenard JR. Tapping the Brakes: Cellular and Synaptic Mechanisms that Regulate Thalamic Oscillations. Neuron 2017; 92:687-704. [PMID: 27883901 DOI: 10.1016/j.neuron.2016.10.024] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 10/03/2016] [Accepted: 10/10/2016] [Indexed: 12/26/2022]
Abstract
Thalamic oscillators contribute to both normal rhythms associated with sleep and anesthesia and abnormal, hypersynchronous oscillations that manifest behaviorally as absence seizures. In this review, we highlight new findings that refine thalamic contributions to cortical rhythms and suggest that thalamic oscillators may be subject to both local and global control. We describe endogenous thalamic mechanisms that limit network synchrony and discuss how these protective brakes might be restored to prevent absence seizures. Finally, we describe how intrinsic and circuit-level specializations among thalamocortical loops may determine their involvement in widespread oscillations and render subsets of thalamic nuclei especially vulnerable to pathological synchrony.
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Affiliation(s)
- P Michelle Fogerson
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - John R Huguenard
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA.
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18
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Chiosa V, Groppa SA, Ciolac D, Koirala N, Mişina L, Winter Y, Moldovanu M, Muthuraman M, Groppa S. Breakdown of Thalamo-Cortical Connectivity Precedes Spike Generation in Focal Epilepsies. Brain Connect 2017; 7:309-320. [DOI: 10.1089/brain.2017.0487] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Vitalie Chiosa
- Department of Neurology, Neuroimaging and Neurostimulation, Focus Program Translational Neuroscience (FTN), Rhine-Main Neuroscience Network (rmn2), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
- Department of Neurology and Neurosurgery, National Center of Epileptology, Institute of Emergency Medicine, Chisinau, Moldova
- Laboratory of Neurobiology and Medical Genetics, State University of Medicine and Pharmacy “Nicolae Testemiţanu,” Chisinau, Moldova
| | - Stanislav A. Groppa
- Department of Neurology and Neurosurgery, National Center of Epileptology, Institute of Emergency Medicine, Chisinau, Moldova
- Laboratory of Neurobiology and Medical Genetics, State University of Medicine and Pharmacy “Nicolae Testemiţanu,” Chisinau, Moldova
| | - Dumitru Ciolac
- Department of Neurology, Neuroimaging and Neurostimulation, Focus Program Translational Neuroscience (FTN), Rhine-Main Neuroscience Network (rmn2), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
- Department of Neurology and Neurosurgery, National Center of Epileptology, Institute of Emergency Medicine, Chisinau, Moldova
- Laboratory of Neurobiology and Medical Genetics, State University of Medicine and Pharmacy “Nicolae Testemiţanu,” Chisinau, Moldova
| | - Nabin Koirala
- Department of Neurology, Neuroimaging and Neurostimulation, Focus Program Translational Neuroscience (FTN), Rhine-Main Neuroscience Network (rmn2), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Liudmila Mişina
- Department of Neurology and Neurosurgery, National Center of Epileptology, Institute of Emergency Medicine, Chisinau, Moldova
- Laboratory of Neurobiology and Medical Genetics, State University of Medicine and Pharmacy “Nicolae Testemiţanu,” Chisinau, Moldova
| | - Yaroslav Winter
- Department of Neurology, Neuroimaging and Neurostimulation, Focus Program Translational Neuroscience (FTN), Rhine-Main Neuroscience Network (rmn2), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | | | - Muthuraman Muthuraman
- Department of Neurology, Neuroimaging and Neurostimulation, Focus Program Translational Neuroscience (FTN), Rhine-Main Neuroscience Network (rmn2), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Sergiu Groppa
- Department of Neurology, Neuroimaging and Neurostimulation, Focus Program Translational Neuroscience (FTN), Rhine-Main Neuroscience Network (rmn2), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
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19
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Ye Z, Yu X, Houston CM, Aboukhalil Z, Franks NP, Wisden W, Brickley SG. Fast and Slow Inhibition in the Visual Thalamus Is Influenced by Allocating GABA A Receptors with Different γ Subunits. Front Cell Neurosci 2017; 11:95. [PMID: 28420966 PMCID: PMC5378722 DOI: 10.3389/fncel.2017.00095] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/20/2017] [Indexed: 12/02/2022] Open
Abstract
Cell-type specific differences in the kinetics of inhibitory postsynaptic conductance changes (IPSCs) are believed to impact upon network dynamics throughout the brain. Much attention has focused on how GABAA receptor (GABAAR) α and β subunit diversity will influence IPSC kinetics, but less is known about the influence of the γ subunit. We have examined whether GABAAR γ subunit heterogeneity influences IPSC properties in the thalamus. The γ2 subunit gene was deleted from GABAARs selectively in the dorsal lateral geniculate nucleus (dLGN). The removal of the γ2 subunit from the dLGN reduced the overall spontaneous IPSC (sIPSC) frequency across all relay cells and produced an absence of IPSCs in a subset of relay neurons. The remaining slower IPSCs were both insensitive to diazepam and zinc indicating the absence of the γ2 subunit. Because these slower IPSCs were potentiated by methyl-6,7-dimethoxy-4-ethyl-β-carboline-3-carboxylate (DMCM), we propose these IPSCs involve γ1 subunit-containing GABAAR activation. Therefore, γ subunit heterogeneity appears to influence the kinetics of GABAAR-mediated synaptic transmission in the visual thalamus in a cell-selective manner. We suggest that activation of γ1 subunit-containing GABAARs give rise to slower IPSCs in general, while faster IPSCs tend to be mediated by γ2 subunit-containing GABAARs.
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Affiliation(s)
- Zhiwen Ye
- Department of Life Sciences, Imperial College LondonLondon, UK.,Department of Neurophysiology, The Francis Crick InstituteLondon, UK
| | - Xiao Yu
- Department of Life Sciences, Imperial College LondonLondon, UK
| | | | | | | | - William Wisden
- Department of Life Sciences, Imperial College LondonLondon, UK
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20
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Toward understanding thalamocortical dysfunction in schizophrenia through computational models of neural circuit dynamics. Schizophr Res 2017; 180:70-77. [PMID: 27784534 PMCID: PMC5263120 DOI: 10.1016/j.schres.2016.10.021] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 10/11/2016] [Accepted: 10/14/2016] [Indexed: 01/09/2023]
Abstract
The thalamus is implicated in the neuropathology of schizophrenia, and multiple modalities of noninvasive neuroimaging provide converging evidence for altered thalamocortical dynamics in the disorder, such as functional connectivity and oscillatory power. However, it remains a challenge to link these neuroimaging biomarkers to underlying neural circuit mechanisms. One potential path forward is a "Computational Psychiatry" approach that leverages computational models of neural circuits to make predictions for the dynamical impact dynamical impact on specific thalamic disruptions hypothesized to occur in the pathophysiology of schizophrenia. Here we review biophysically-based computational models of neural circuit dynamics for large-scale resting-state networks which have been applied to schizophrenia, and for thalamic oscillations. As a key aspect of thalamocortical dysconnectivity in schizophrenia is its regional specificity, it is important to consider potential sources of intrinsic heterogeneity of cellular and circuit properties across cortical and thalamic structures.
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21
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Kim HR, Hong SZ, Fiorillo CD. T-type calcium channels cause bursts of spikes in motor but not sensory thalamic neurons during mimicry of natural patterns of synaptic input. Front Cell Neurosci 2015; 9:428. [PMID: 26582654 PMCID: PMC4631812 DOI: 10.3389/fncel.2015.00428] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 10/13/2015] [Indexed: 12/30/2022] Open
Abstract
Although neurons within intact nervous systems can be classified as ‘sensory’ or ‘motor,’ it is not known whether there is any general distinction between sensory and motor neurons at the cellular or molecular levels. Here, we extend and test a theory according to which activation of certain subtypes of voltage-gated ion channel (VGC) generate patterns of spikes in neurons of motor systems, whereas VGC are proposed to counteract patterns in sensory neurons. We previously reported experimental evidence for the theory from visual thalamus, where we found that T-type calcium channels (TtCCs) did not cause bursts of spikes but instead served the function of ‘predictive homeostasis’ to maximize the causal and informational link between retinogeniculate excitation and spike output. Here, we have recorded neurons in brain slices from eight sensory and motor regions of rat thalamus while mimicking key features of natural excitatory and inhibitory post-synaptic potentials. As predicted by theory, TtCC did cause bursts of spikes in motor thalamus. TtCC-mediated responses in motor thalamus were activated at more hyperpolarized potentials and caused larger depolarizations with more spikes than in visual and auditory thalamus. Somatosensory thalamus is known to be more closely connected to motor regions relative to auditory and visual thalamus, and likewise the strength of its TtCC responses was intermediate between these regions and motor thalamus. We also observed lower input resistance, as well as limited evidence of stronger hyperpolarization-induced (‘H-type’) depolarization, in nuclei closer to motor output. These findings support our theory of a specific difference between sensory and motor neurons at the cellular level.
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Affiliation(s)
- Haram R Kim
- Department of Bio and Brain Engineering, KAIST Daejeon, South Korea
| | - Su Z Hong
- Department of Bio and Brain Engineering, KAIST Daejeon, South Korea
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22
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Elijah DH, Samengo I, Montemurro MA. Thalamic neuron models encode stimulus information by burst-size modulation. Front Comput Neurosci 2015; 9:113. [PMID: 26441623 PMCID: PMC4585143 DOI: 10.3389/fncom.2015.00113] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 08/28/2015] [Indexed: 11/13/2022] Open
Abstract
Thalamic neurons have been long assumed to fire in tonic mode during perceptive states, and in burst mode during sleep and unconsciousness. However, recent evidence suggests that bursts may also be relevant in the encoding of sensory information. Here, we explore the neural code of such thalamic bursts. In order to assess whether the burst code is generic or whether it depends on the detailed properties of each bursting neuron, we analyzed two neuron models incorporating different levels of biological detail. One of the models contained no information of the biophysical processes entailed in spike generation, and described neuron activity at a phenomenological level. The second model represented the evolution of the individual ionic conductances involved in spiking and bursting, and required a large number of parameters. We analyzed the models' input selectivity using reverse correlation methods and information theory. We found that n-spike bursts from both models transmit information by modulating their spike count in response to changes to instantaneous input features, such as slope, phase, amplitude, etc. The stimulus feature that is most efficiently encoded by bursts, however, need not coincide with one of such classical features. We therefore searched for the optimal feature among all those that could be expressed as a linear transformation of the time-dependent input current. We found that bursting neurons transmitted 6 times more information about such more general features. The relevant events in the stimulus were located in a time window spanning ~100 ms before and ~20 ms after burst onset. Most importantly, the neural code employed by the simple and the biologically realistic models was largely the same, implying that the simple thalamic neuron model contains the essential ingredients that account for the computational properties of the thalamic burst code. Thus, our results suggest the n-spike burst code is a general property of thalamic neurons.
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Affiliation(s)
- Daniel H Elijah
- Faculty of Life Sciences, The University of Manchester Manchester, UK
| | - Inés Samengo
- Statistical and Interdisciplinary Physics Group, Instituto Balseiro and Centro Atómico Bariloche San Carlos de Bariloche, Argentina
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23
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Cortes N, van Vreeswijk C. Pulvinar thalamic nucleus allows for asynchronous spike propagation through the cortex. Front Comput Neurosci 2015; 9:60. [PMID: 26042026 PMCID: PMC4436891 DOI: 10.3389/fncom.2015.00060] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 05/10/2015] [Indexed: 11/13/2022] Open
Abstract
We create two multilayered feedforward networks composed of excitatory and inhibitory integrate-and-fire neurons in the balanced state to investigate the role of cortico-pulvino-cortical connections. The first network consists of ten feedforward levels where a Poisson spike train with varying firing rate is applied as an input in layer one. Although the balanced state partially avoids spike synchronization during the transmission, the average firing-rate in the last layer either decays or saturates depending on the feedforward pathway gain. The last layer activity is almost independent of the input even for a carefully chosen intermediate gain. Adding connections to the feedforward pathway by a nine areas Pulvinar structure improves the firing-rate propagation to become almost linear among layers. Incoming strong pulvinar spikes balance the low feedforward gain to have a unit input-output relation in the last layer. Pulvinar neurons evoke a bimodal activity depending on the magnitude input: synchronized spike bursts between 20 and 80 Hz and an asynchronous activity for very both low and high frequency inputs. In the first regime, spikes of last feedforward layer neurons are asynchronous with weak, low frequency, oscillations in the rate. Here, the uncorrelated incoming feedforward pathway washes out the synchronized thalamic bursts. In the second regime, spikes in the whole network are asynchronous. As the number of cortical layers increases, long-range pulvinar connections can link directly two or more cortical stages avoiding their either saturation or gradual activity falling. The Pulvinar acts as a shortcut that supplies the input-output firing-rate relationship of two separated cortical areas without changing the strength of connections in the feedforward pathway.
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Affiliation(s)
- Nelson Cortes
- Institut de la Vision, UMRS 968 UPMC, INSERM, Centre National de la Recherche Scientifique U7210, CHNO Quinze-Vingts Paris, France
| | - Carl van Vreeswijk
- Physiology and Pathology, Center for Neurophysics, University Paris Descartes and Centre National de la Recherche Scientifique UMR 8119 Paris, France
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24
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Abstract
Numerous electrophysiological and neuroimaging studies have reported neurophysiological and cognitive deficits in schizophrenia patients during wakefulness. However, these findings have been inconsistently replicated across different groups of patients, thus complicating the identification of underlying neuronal defects. Sleep minimizes possible waking-related confounds, including decreased motivation and presence of active symptoms. Additionally, the two main sleep rhythms, slow waves and spindles, reflect the intrinsic activity of corticothalamic circuits and are associated with cognitive activities, including learning and memory, occurring during wakefulness. In this review I will present the most relevant sleep findings in schizophrenia, with particular emphasis on several recent studies that have consistently reported sleep spindle deficits in patients with schizophrenia. I will then elaborate on how these findings may contribute to a better understanding of the neurobiology of schizophrenia as well as to the development of novel pharmacological and non-pharmacological interventions to ameliorate the symptoms and cognitive impairments of schizophrenia patients.
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Affiliation(s)
- Fabio Ferrarelli
- To whom correspondence should be addressed: Fabio Ferrarelli, MD, PhD, University of Wisconsin-Madison, USA, , tel: 6082636100
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25
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Kimura A, Imbe H. Anatomically structured burst spiking of thalamic reticular nucleus cells: implications for distinct modulations of sensory processing in lemniscal and non-lemniscal thalamocortical loop circuitries. Eur J Neurosci 2015; 41:1276-93. [DOI: 10.1111/ejn.12874] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 02/11/2015] [Indexed: 11/29/2022]
Affiliation(s)
- Akihisa Kimura
- Department of Physiology; Wakayama Medical University; Wakayama Kimiidera 811-1 641-8509 Wakayama Japan
| | - Hiroki Imbe
- Department of Physiology; Wakayama Medical University; Wakayama Kimiidera 811-1 641-8509 Wakayama Japan
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26
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Schmid MC, Maier A. To see or not to see--thalamo-cortical networks during blindsight and perceptual suppression. Prog Neurobiol 2015; 126:36-48. [PMID: 25661166 DOI: 10.1016/j.pneurobio.2015.01.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 01/05/2015] [Accepted: 01/14/2015] [Indexed: 11/15/2022]
Abstract
Even during moments when we fail to be fully aware of our environment, our brains never go silent. Instead, it appears that the brain can also operate in an alternate, unconscious mode. Delineating unconscious from conscious neural processes is a promising first step toward investigating how awareness emerges from brain activity. Here we focus on recent insights into the neuronal processes that contribute to visual function in the absence of a conscious visual percept. Drawing on insights from findings on the phenomenon of blindsight that results from injury to primary visual cortex and the results of experimentally induced perceptual suppression, we describe what kind of visual information the visual system analyzes unconsciously and we discuss the neuronal routing and responses that accompany this process. We conclude that unconscious processing of certain visual stimulus attributes, such as the presence of visual motion or the emotional expression of a face can occur in a geniculo-cortical circuit that runs independent from and in parallel to the predominant route through primary visual cortex. We speculate that in contrast, bidirectional neuronal interactions between cortex and the thalamic pulvinar nucleus that support large-scale neuronal integration and visual awareness are impeded during blindsight and perceptual suppression.
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Affiliation(s)
- Michael C Schmid
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Deutschordenstraße 46, Frankfurt a. M. 60528, Germany.
| | - Alexander Maier
- Vanderbilt University, Department of Psychology, 111 21st Avenue South, 301 Wilson Hall, Nashville, TN 37240, USA.
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Vukadinovic Z. Elevated striatal dopamine attenuates nigrothalamic inputs and impairs transthalamic cortico-cortical communication in schizophrenia: A hypothesis. Med Hypotheses 2015; 84:47-52. [DOI: 10.1016/j.mehy.2014.11.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Revised: 10/28/2014] [Accepted: 11/11/2014] [Indexed: 12/12/2022]
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28
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Allken V, Chepkoech JL, Einevoll GT, Halnes G. The subcellular distribution of T-type Ca2+ channels in interneurons of the lateral geniculate nucleus. PLoS One 2014; 9:e107780. [PMID: 25268996 PMCID: PMC4182431 DOI: 10.1371/journal.pone.0107780] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 07/17/2014] [Indexed: 12/31/2022] Open
Abstract
Inhibitory interneurons (INs) in the lateral geniculate nucleus (LGN) provide both axonal and dendritic GABA output to thalamocortical relay cells (TCs). Distal parts of the IN dendrites often enter into complex arrangements known as triadic synapses, where the IN dendrite plays a dual role as postsynaptic to retinal input and presynaptic to TC dendrites. Dendritic GABA release can be triggered by retinal input, in a highly localized process that is functionally isolated from the soma, but can also be triggered by somatically elicited Ca2+-spikes and possibly by backpropagating action potentials. Ca2+-spikes in INs are predominantly mediated by T-type Ca2+-channels (T-channels). Due to the complex nature of the dendritic signalling, the function of the IN is likely to depend critically on how T-channels are distributed over the somatodendritic membrane (T-distribution). To study the relationship between the T-distribution and several IN response properties, we here run a series of simulations where we vary the T-distribution in a multicompartmental IN model with a realistic morphology. We find that the somatic response to somatic current injection is facilitated by a high T-channel density in the soma-region. Conversely, a high T-channel density in the distal dendritic region is found to facilitate dendritic signalling in both the outward direction (increases the response in distal dendrites to somatic input) and the inward direction (the soma responds stronger to distal synaptic input). The real T-distribution is likely to reflect a compromise between several neural functions, involving somatic response patterns and dendritic signalling.
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Affiliation(s)
- Vaneeda Allken
- Dept. of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Ås, Norway
| | - Joy-Loi Chepkoech
- Dept. of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Ås, Norway; Dept. of Psychology, University of Oslo, Oslo, Norway
| | - Gaute T Einevoll
- Dept. of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Ås, Norway; Dept. of Physics, University of Oslo, Oslo, Norway
| | - Geir Halnes
- Dept. of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Ås, Norway
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29
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Hong SZ, Kim HR, Fiorillo CD. T-type calcium channels promote predictive homeostasis of input-output relations in thalamocortical neurons of lateral geniculate nucleus. Front Comput Neurosci 2014; 8:98. [PMID: 25221503 PMCID: PMC4147392 DOI: 10.3389/fncom.2014.00098] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Accepted: 08/01/2014] [Indexed: 12/28/2022] Open
Abstract
A general theory views the function of all neurons as prediction, and one component of this theory is that of “predictive homeostasis” or “prediction error.” It is well established that sensory systems adapt so that neuronal output maintains sensitivity to sensory input, in accord with information theory. Predictive homeostasis applies the same principle at the cellular level, where the challenge is to maintain membrane excitability at the optimal homeostatic level so that spike generation is maximally sensitive to small gradations in synaptic drive. Negative feedback is a hallmark of homeostatic mechanisms, as exemplified by depolarization-activated potassium channels. In contrast, T-type calcium channels exhibit positive feedback that appears at odds with the theory. In thalamocortical neurons of lateral geniculate nucleus (LGN), T-type channels are capable of causing bursts of spikes with an all-or-none character in response to excitation from a hyperpolarized potential. This “burst mode” would partially uncouple visual input from spike output and reduce the information spikes convey about gradations in visual input. However, past observations of T-type-driven bursts may have resulted from unnaturally high membrane excitability. Here we have mimicked within rat brain slices the patterns of synaptic conductance that occur naturally during vision. In support of the theory of predictive homeostasis, we found that T-type channels restored excitability toward its homeostatic level during periods of hyperpolarization. Thus, activation of T-type channels allowed two retinal input spikes to cause one output spike on average, and we observed almost no instances in which output count exceeded input count (a “burst”). T-type calcium channels therefore help to maintain a single optimal mode of transmission rather than creating a second mode. More fundamentally our results support the general theory, which seeks to predict the properties of a neuron's ion channels and synapses given knowledge of natural patterns of synaptic input.
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Affiliation(s)
- Su Z Hong
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology Daejeon, South Korea
| | - Haram R Kim
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology Daejeon, South Korea
| | - Christopher D Fiorillo
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology Daejeon, South Korea
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30
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Buchmann A, Dentico D, Peterson MJ, Riedner BA, Sarasso S, Massimini M, Tononi G, Ferrarelli F. Reduced mediodorsal thalamic volume and prefrontal cortical spindle activity in schizophrenia. Neuroimage 2014; 102 Pt 2:540-7. [PMID: 25139002 DOI: 10.1016/j.neuroimage.2014.08.017] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 07/29/2014] [Accepted: 08/09/2014] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND We recently found marked deficits in sleep spindles, non-rapid eye movement (NREM) sleep oscillations that are generated within the thalamus and then amplified and sustained in the cortex, in patients with schizophrenia compared to both healthy and psychiatric controls. Here, we investigated the thalamic and cortical contributions to these sleep spindle deficits. METHODS Anatomical volume of interest analysis (i.e., thalamic volumes) and electroencephalogram (EEG) source modeling (i.e., spindle-related cortical currents) were performed in patients with schizophrenia and healthy comparison subjects. FINDINGS Schizophrenia patients had reduced mediodorsal (MD) thalamic volumes, especially on the left side, compared to healthy controls, whereas whole thalami and lateral geniculate nuclei did not differ between groups. Furthermore, left MD volumes were strongly correlated with the number of scalp-recorded spindles in an anterior frontal region, and cortical currents underlying these anterior frontal spindles were localized in the prefrontal cortex, in Brodmann area (BA) 10. Finally, prefrontal currents at the peak of spindle activity were significantly reduced in schizophrenia patients and correlated with their performance in an abstraction/working memory task. CONCLUSION Altogether, these findings point to deficits in a specific thalamo-cortical circuitry in schizophrenia, which is associated with some cognitive deficits commonly reported in those patients.
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Affiliation(s)
| | | | | | | | - Simone Sarasso
- Department of Psychiatry, University of WI-Madison, USA; Department of Clinical Sciences, University of Milan, Italy
| | - Marcello Massimini
- Department of Psychiatry, University of WI-Madison, USA; Department of Clinical Sciences, University of Milan, Italy
| | - Giulio Tononi
- Department of Psychiatry, University of WI-Madison, USA
| | - Fabio Ferrarelli
- Department of Psychiatry, University of WI-Madison, USA; Department of Clinical Sciences, University of Milan, Italy.
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Amarillo Y, Zagha E, Mato G, Rudy B, Nadal MS. The interplay of seven subthreshold conductances controls the resting membrane potential and the oscillatory behavior of thalamocortical neurons. J Neurophysiol 2014; 112:393-410. [PMID: 24760784 DOI: 10.1152/jn.00647.2013] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The signaling properties of thalamocortical (TC) neurons depend on the diversity of ion conductance mechanisms that underlie their rich membrane behavior at subthreshold potentials. Using patch-clamp recordings of TC neurons in brain slices from mice and a realistic conductance-based computational model, we characterized seven subthreshold ion currents of TC neurons and quantified their individual contributions to the total steady-state conductance at levels below tonic firing threshold. We then used the TC neuron model to show that the resting membrane potential results from the interplay of several inward and outward currents over a background provided by the potassium and sodium leak currents. The steady-state conductances of depolarizing Ih (hyperpolarization-activated cationic current), IT (low-threshold calcium current), and INaP (persistent sodium current) move the membrane potential away from the reversal potential of the leak conductances. This depolarization is counteracted in turn by the hyperpolarizing steady-state current of IA (fast transient A-type potassium current) and IKir (inwardly rectifying potassium current). Using the computational model, we have shown that single parameter variations compatible with physiological or pathological modulation promote burst firing periodicity. The balance between three amplifying variables (activation of IT, activation of INaP, and activation of IKir) and three recovering variables (inactivation of IT, activation of IA, and activation of Ih) determines the propensity, or lack thereof, of repetitive burst firing of TC neurons. We also have determined the specific roles that each of these variables have during the intrinsic oscillation.
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Affiliation(s)
- Yimy Amarillo
- Consejo Nacional de Investigaciones Científicas y Técnicas, Física Estadística e Interdisciplinaria, Centro Atómico Bariloche, San Carlos de Bariloche, Rio Negro, Argentina; Smilow Neuroscience Program, New York University Medical Center, New York, New York; and
| | - Edward Zagha
- Smilow Neuroscience Program, New York University Medical Center, New York, New York; and
| | - German Mato
- Consejo Nacional de Investigaciones Científicas y Técnicas, Física Estadística e Interdisciplinaria, Centro Atómico Bariloche, San Carlos de Bariloche, Rio Negro, Argentina; Comisión Nacional de Energía Atómica, Centro Atómico Bariloche and Instituto Balseiro, San Carlos de Bariloche, Rio Negro, Argentina
| | - Bernardo Rudy
- Smilow Neuroscience Program, New York University Medical Center, New York, New York; and
| | - Marcela S Nadal
- Consejo Nacional de Investigaciones Científicas y Técnicas, Física Estadística e Interdisciplinaria, Centro Atómico Bariloche, San Carlos de Bariloche, Rio Negro, Argentina
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32
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Edgerton JR, Jaeger D. Optogenetic activation of nigral inhibitory inputs to motor thalamus in the mouse reveals classic inhibition with little potential for rebound activation. Front Cell Neurosci 2014; 8:36. [PMID: 24574972 PMCID: PMC3920182 DOI: 10.3389/fncel.2014.00036] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Accepted: 01/23/2014] [Indexed: 11/13/2022] Open
Abstract
The inhibitory output from the internal pallidum and substantia nigra to the thalamus forms an important link in the transmission of basal ganglia processing to cortex. Two hypotheses consider either inhibition of thalamic activity or thalamic excitation via post-inhibitory rebound burst firing as the functional mode of this link. We used optogenetics to characterize the synaptic properties of nigral input to motor thalamus in adult mouse brain slices, and to determine in what conditions the nigral inhibition of motor thalamus is transmitted via inhibition or rebound firing. Our results are more consistent with graded inhibition of spiking for conditions expected in normal awake animals, because inhibitory potentials from nigral input were generally not sufficient to elicit rebound spikes when the thalamic neurons were actively firing. However, with bursty or fast trains of nigral input low-threshold rebound spike bursts could be triggered for low levels of excitation. This may form the basis of pathological burst generation and transmission in parkinsonian conditions.
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Affiliation(s)
| | - Dieter Jaeger
- Department of Biology, Emory University Atlanta, GA, USA
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33
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Cannabis, psychosis and the thalamus: A theoretical review. Neurosci Biobehav Rev 2013; 37:658-67. [DOI: 10.1016/j.neubiorev.2013.02.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 01/21/2013] [Accepted: 02/19/2013] [Indexed: 11/18/2022]
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Kimura A, Yokoi I, Imbe H, Donishi T, Kaneoke Y. Distinctions in burst spiking between thalamic reticular nucleus cells projecting to the dorsal lateral geniculate and lateral posterior nuclei in the anesthetized rat. Neuroscience 2012; 226:208-26. [PMID: 22989916 DOI: 10.1016/j.neuroscience.2012.09.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 09/06/2012] [Accepted: 09/06/2012] [Indexed: 10/27/2022]
Abstract
Thalamic cell activity is under a significant influence of inhibition from the thalamic reticular nucleus (TRN) that is composed of domains connected with first and higher order thalamic nuclei, which are thought to subserve transmission of sensory inputs to the cortex and cortico-thalamo-cortical transmission of cortical outputs, respectively. Provided that TRN cells have distinct activities along with their projections to first and higher order thalamic nuclei, TRN cells could shape cell activities of the two thalamic nuclei in different manners for the distinct functions. In anesthetized rats, visual response and spontaneous activity were recorded from TRN cells projecting to the dorsal lateral geniculate (first order) and lateral posterior (higher order) nuclei (TRN-DLG and TRN-LP cells), using juxta-cellular recording and labeling techniques. TRN-DLG cells had a higher propensity for burst spiking and exhibited bursts of larger numbers of spikes with shorter inter-spike intervals as compared to TRN-LP cells in both visual response and spontaneous activity. Sustained effects of visual input on burst spiking were recognized in recurrent activation of TRN-DLG but not of TRN-LP cells. Further, the features of burst spiking were related with the locations of topographically connected cell bodies and terminal fields. The difference in burst spiking contrasts with the difference between thalamic cells in the DLG and LP, which show low and high levels of burst spiking, respectively. The synergy between thalamic and TRN cell activities with their contrasting features of burst spiking may compose distinctive sensory processing and attentional gating functions of geniculate and extra-geniculate systems.
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Affiliation(s)
- A Kimura
- Department of Physiology, Wakayama Medical University, Wakayama Kimiidera 811-1, 641-8509 Wakayama, Japan.
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