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Wijesinghe R, Protti DA, Camp AJ. Vestibular Interactions in the Thalamus. Front Neural Circuits 2015; 9:79. [PMID: 26696836 PMCID: PMC4667082 DOI: 10.3389/fncir.2015.00079] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 11/10/2015] [Indexed: 01/31/2023] Open
Abstract
It has long been known that the vast majority of all information en route to the cerebral cortex must first pass through the thalamus. The long held view that the thalamus serves as a simple hi fidelity relay station for sensory information to the cortex, however, has over recent years been dispelled. Indeed, multiple projections from the vestibular nuclei to thalamic nuclei (including the ventrobasal nuclei, and the geniculate bodies)- regions typically associated with other modalities- have been described. Further, some thalamic neurons have been shown to respond to stimuli presented from across sensory modalities. For example, neurons in the rat anterodorsal and laterodorsal nuclei of the thalamus respond to visual, vestibular, proprioceptive and somatosensory stimuli and integrate this information to compute heading within the environment. Together, these findings imply that the thalamus serves crucial integrative functions, at least in regard to vestibular processing, beyond that imparted by a “simple” relay. In this mini review we outline the vestibular inputs to the thalamus and provide some clinical context for vestibular interactions in the thalamus. We then focus on how vestibular inputs interact with other sensory systems and discuss the multisensory integration properties of the thalamus.
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Affiliation(s)
- Rajiv Wijesinghe
- Sensory Systems and Integration Laboratory, Sydney Medical School, Discipline of Biomedical Science, University of Sydney Sydney, NSW, Australia
| | - Dario A Protti
- Vision Laboratory, Sydney Medical School, Discipline of Physiology, University of Sydney Sydney, NSW, Australia
| | - Aaron J Camp
- Sensory Systems and Integration Laboratory, Sydney Medical School, Discipline of Biomedical Science, University of Sydney Sydney, NSW, Australia
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202
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Functional Microarchitecture of the Mouse Dorsal Inferior Colliculus Revealed through In Vivo Two-Photon Calcium Imaging. J Neurosci 2015; 35:10927-39. [PMID: 26245957 DOI: 10.1523/jneurosci.0103-15.2015] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
UNLABELLED The inferior colliculus (IC) is an obligatory relay for ascending auditory inputs from the brainstem and receives descending input from the auditory cortex. The IC comprises a central nucleus (CNIC), surrounded by several shell regions, but the internal organization of this midbrain nucleus remains incompletely understood. We used two-photon calcium imaging to study the functional microarchitecture of both neurons in the mouse dorsal IC and corticocollicular axons that terminate there. In contrast to previous electrophysiological studies, our approach revealed a clear functional distinction between the CNIC and the dorsal cortex of the IC (DCIC), suggesting that the mouse midbrain is more similar to that of other mammals than previously thought. We found that the DCIC comprises a thin sheet of neurons, sometimes extending barely 100 μm below the pial surface. The sound frequency representation in the DCIC approximated the mouse's full hearing range, whereas dorsal CNIC neurons almost exclusively preferred low frequencies. The response properties of neurons in these two regions were otherwise surprisingly similar, and the frequency tuning of DCIC neurons was only slightly broader than that of CNIC neurons. In several animals, frequency gradients were observed in the DCIC, and a comparable tonotopic arrangement was observed across the boutons of the corticocollicular axons, which form a dense mesh beneath the dorsal surface of the IC. Nevertheless, acoustically responsive corticocollicular boutons were sparse, produced unreliable responses, and were more broadly tuned than DCIC neurons, suggesting that they have a largely modulatory rather than driving influence on auditory midbrain neurons. SIGNIFICANCE STATEMENT Due to its genetic tractability, the mouse is fast becoming the most popular animal model for sensory neuroscience. Nevertheless, many aspects of its neural architecture are still poorly understood. Here, we image the dorsal auditory midbrain and its inputs from the cortex, revealing a hitherto hidden level of organization and paving the way for the direct observation of corticocollicular interactions. We show that a precise functional organization exists in the mouse auditory midbrain, which has been missed by previous, more macroscopic approaches. The fine-scale distribution of sound-frequency tuning suggests that the mouse midbrain is more similar to that of other mammals than previously thought and contrasts with the more heterogeneous organization reported in imaging studies of auditory cortex.
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203
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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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204
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Firk C, Mainz V, Schulte-Ruether M, Fink G, Herpertz-Dahlmann B, Konrad K. Implicit sequence learning in juvenile anorexia nervosa: neural mechanisms and the impact of starvation. J Child Psychol Psychiatry 2015; 56:1168-76. [PMID: 25623396 DOI: 10.1111/jcpp.12384] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/09/2014] [Indexed: 01/10/2023]
Abstract
BACKGROUND Previous studies have reported that cognitive deficits occur in patients with anorexia nervosa (AN) and that these deficits may represent a predisposition towards developing AN or perpetuate the disorder. Specifically, dysfunctional implicit learning may contribute to the development of highly resistant dieting behaviours that are fundamental to the persistence of the disorder. Thus, the aims of this study were (a) to investigate implicit sequence learning in adolescent patients with AN before and after weight recovery and (b) to elucidate the associated neural mechanisms in acute AN relative to healthy controls. METHODS In a behavioural study, implicit sequence learning was assessed using a serial reaction time task in 27 adolescents with AN before (T1) and after weight recovery (T2) compared with age-matched healthy controls (HC) who were assessed at similar time intervals. The neural correlates of implicit sequence learning were subsequently investigated in 19 AN patients shortly after they were admitted to the hospital and 20 HC using functional magnetic resonance imaging (fMRI). RESULTS At T1, AN patients showed reduced sequence learning compared with HC. However, no behavioural differences between HC and AN patients were found at T2. At the neural level, acute AN patients showed reduced thalamic activation during sequence learning compared with HC subjects. CONCLUSIONS Our data suggest that the impaired implicit learning observed in adolescent AN patients before weight gain is a state-related dysfunction that normalises with weight gain. Thus, implicit learning deficits do not appear to represent a predisposition towards developing AN; rather, these deficits should be considered when planning psychotherapeutic interventions for acute AN. Reduced thalamic activation during the acute stage of AN may indicate a starvation-induced dysfunction of the neural circuitry that is involved in behavioural flexibility.
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Affiliation(s)
- Christine Firk
- Department of Child and Adolescent Psychiatry, University Hospital RWTH Aachen, Aachen, Germany
| | - Verena Mainz
- Department of Child and Adolescent Psychiatry, University Hospital RWTH Aachen, Aachen, Germany
| | - Martin Schulte-Ruether
- Department of Child and Adolescent Psychiatry, University Hospital RWTH Aachen, Aachen, Germany.,Institute of Neuroscience and Medicine (INM-3), Research Centre Juelich, Juelich, Germany
| | - Gereon Fink
- Institute of Neuroscience and Medicine (INM-3), Research Centre Juelich, Juelich, Germany.,Department of Neurology, University Hospital Cologne, Cologne, Germany
| | - Beate Herpertz-Dahlmann
- Department of Child and Adolescent Psychiatry, University Hospital RWTH Aachen, Aachen, Germany
| | - Kerstin Konrad
- Department of Child and Adolescent Psychiatry, University Hospital RWTH Aachen, Aachen, Germany.,Institute of Neuroscience and Medicine (INM-3), Research Centre Juelich, Juelich, Germany
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205
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Hale JR, White TP, Mayhew SD, Wilson RS, Rollings DT, Khalsa S, Arvanitis TN, Bagshaw AP. Altered thalamocortical and intra-thalamic functional connectivity during light sleep compared with wake. Neuroimage 2015; 125:657-667. [PMID: 26499809 DOI: 10.1016/j.neuroimage.2015.10.041] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 09/16/2015] [Accepted: 10/16/2015] [Indexed: 01/14/2023] Open
Abstract
The transition from wakefulness into sleep is accompanied by modified activity in the brain's thalamocortical network. Sleep-related decreases in thalamocortical functional connectivity (FC) have previously been reported, but the extent to which these changes differ between thalamocortical pathways, and patterns of intra-thalamic FC during sleep remain untested. To non-invasively investigate thalamocortical and intra-thalamic FC as a function of sleep stage we recorded simultaneous EEG-fMRI data in 13 healthy participants during their descent into light sleep. Visual scoring of EEG data permitted sleep staging. We derived a functional thalamic parcellation during wakefulness by computing seed-based FC, measured between thalamic voxels and a set of pre-defined cortical regions. Sleep differentially affected FC between these distinct thalamic subdivisions and their associated cortical projections, with significant increases in FC during sleep restricted to sensorimotor connections. In contrast, intra-thalamic FC, both within and between functional thalamic subdivisions, showed significant increases with advancement into sleep. This work demonstrates the complexity and state-specific nature of functional thalamic relationships--both with the cortex and internally--over the sleep/wake cycle, and further highlights the importance of a thalamocortical focus in the study of sleep mechanisms.
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Affiliation(s)
- Joanne R Hale
- School of Psychology, University of Birmingham, Birmingham, UK.
| | - Thomas P White
- School of Psychology, University of Birmingham, Birmingham, UK
| | | | | | - David T Rollings
- School of Psychology, University of Birmingham, Birmingham, UK; Department of Neurophysiology, Queen Elizabeth Hospital, Birmingham, UK
| | - Sakhvinder Khalsa
- School of Psychology, University of Birmingham, Birmingham, UK; Department of Neuropsychiatry, The Barberry National Centre for Mental Health, Birmingham, UK
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206
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Abstract
The human subcortex contains multiple nuclei that govern the transmission of information to and among cortical areas. In the visual domain, these nuclei are organized into retinotopic maps. Because of their small size, these maps have been difficult to precisely measure using phase-encoded functional magnetic resonance imaging, particularly in the eccentricity dimension. Using instead the population receptive field model to estimate the response properties of individual voxels, we were able to resolve two previously unreported retinotopic maps in the thalamic reticular nucleus and the substantia nigra. We measured both the polar angle and eccentricity components, receptive field size and hemodynamic response function delay, in the these nuclei and in the lateral geniculate nucleus, the superior colliculus, and the lateral and intergeniculate pulvinars. The anatomical boundaries of these nuclei were delineated using multiple averaged proton density-weighted images and were used to constrain and confirm the functional activations. Deriving the retinotopic organization of these small, subcortical nuclei is the first step in exploring their response properties and their roles in neural dynamics.
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207
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Su F, Wang J, Deng B, Wei XL, Chen YY, Liu C, Li HY. Adaptive control of Parkinson's state based on a nonlinear computational model with unknown parameters. Int J Neural Syst 2015; 25:1450030. [PMID: 25338775 DOI: 10.1142/s0129065714500300] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The objective here is to explore the use of adaptive input-output feedback linearization method to achieve an improved deep brain stimulation (DBS) algorithm for closed-loop control of Parkinson's state. The control law is based on a highly nonlinear computational model of Parkinson's disease (PD) with unknown parameters. The restoration of thalamic relay reliability is formulated as the desired outcome of the adaptive control methodology, and the DBS waveform is the control input. The control input is adjusted in real time according to estimates of unknown parameters as well as the feedback signal. Simulation results show that the proposed adaptive control algorithm succeeds in restoring the relay reliability of the thalamus, and at the same time achieves accurate estimation of unknown parameters. Our findings point to the potential value of adaptive control approach that could be used to regulate DBS waveform in more effective treatment of PD.
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Affiliation(s)
- Fei Su
- School of Electrical and Automation Engineering, Tianjin University, Tianjin 300072, China
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208
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Schwab S, Koenig T, Morishima Y, Dierks T, Federspiel A, Jann K. Discovering frequency sensitive thalamic nuclei from EEG microstate informed resting state fMRI. Neuroimage 2015; 118:368-75. [DOI: 10.1016/j.neuroimage.2015.06.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 05/04/2015] [Accepted: 06/01/2015] [Indexed: 10/23/2022] Open
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209
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Piché M, Thomas S, Casanova C. Spatiotemporal profiles of receptive fields of neurons in the lateral posterior nucleus of the cat LP-pulvinar complex. J Neurophysiol 2015; 114:2390-403. [PMID: 26289469 DOI: 10.1152/jn.00649.2015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 08/16/2015] [Indexed: 11/22/2022] Open
Abstract
The pulvinar is the largest extrageniculate thalamic visual nucleus in mammals. It establishes reciprocal connections with virtually all visual cortexes and likely plays a role in transthalamic cortico-cortical communication. In cats, the lateral posterior nucleus (LP) of the LP-pulvinar complex can be subdivided in two subregions, the lateral (LPl) and medial (LPm) parts, which receive a predominant input from the striate cortex and the superior colliculus, respectively. Here, we revisit the receptive field structure of LPl and LPm cells in anesthetized cats by determining their first-order spatiotemporal profiles through reverse correlation analysis following sparse noise stimulation. Our data reveal the existence of previously unidentified receptive field profiles in the LP nucleus both in space and time domains. While some cells responded to only one stimulus polarity, the majority of neurons had receptive fields comprised of bright and dark responsive subfields. For these neurons, dark subfields' size was larger than that of bright subfields. A variety of receptive field spatial organization types were identified, ranging from totally overlapped to segregated bright and dark subfields. In the time domain, a large spectrum of activity overlap was found, from cells with temporally coinciding subfield activity to neurons with distinct, time-dissociated subfield peak activity windows. We also found LP neurons with space-time inseparable receptive fields and neurons with multiple activity periods. Finally, a substantial degree of homology was found between LPl and LPm first-order receptive field spatiotemporal profiles, suggesting a high integration of cortical and subcortical inputs within the LP-pulvinar complex.
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Affiliation(s)
- Marilyse Piché
- Visual Neuroscience Laboratory, School of Optometry, Université de Montréal, Montréal, Québec, Canada
| | - Sébastien Thomas
- Visual Neuroscience Laboratory, School of Optometry, Université de Montréal, Montréal, Québec, Canada
| | - Christian Casanova
- Visual Neuroscience Laboratory, School of Optometry, Université de Montréal, Montréal, Québec, Canada
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210
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Wolff M, Faugère A, Desfosses É, Coutureau É, Marchand AR. Mediodorsal but not anterior thalamic nuclei lesions impair acquisition of a conditional discrimination task. Neurobiol Learn Mem 2015; 125:80-4. [PMID: 26254715 DOI: 10.1016/j.nlm.2015.07.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 07/22/2015] [Accepted: 07/29/2015] [Indexed: 12/13/2022]
Abstract
The limbic thalamus is a heterogeneous structure with distinctive cortical connectivity. A recent review suggests that the mediodorsal thalamic nucleus (MD), unlike the anterior thalamic nuclei (ATN), may be involved in selecting relevant information in tasks relying on executive functions. We compared the effects of excitotoxic lesions of the MD or the ATN on the acquisition of a simple conditional discrimination in rats. When required to choose from two levers according to auditory or visual cues, ATN rats and sham-lesioned rats performed to the same levels and displayed similar acquisition curves. Under the same conditions, MD rats' acquisition of the task was markedly delayed. This group nevertheless attained nearly normal performances after more extensive training. Furthermore, all rats learned reversal of the original discrimination at the same rate. These results highlight functional specialization within the limbic thalamus and support the notion that MD contributes to the identification of relevant dimensions in conditional tasks during the initial stages of acquisition.
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Affiliation(s)
- Mathieu Wolff
- CNRS, INCIA, UMR 5287, 33076 Bordeaux, France; Université de Bordeaux, INCIA, UMR 5287, 33076 Bordeaux, France.
| | - Angélique Faugère
- CNRS, INCIA, UMR 5287, 33076 Bordeaux, France; Université de Bordeaux, INCIA, UMR 5287, 33076 Bordeaux, France
| | - Émilie Desfosses
- CNRS, INCIA, UMR 5287, 33076 Bordeaux, France; Université de Bordeaux, INCIA, UMR 5287, 33076 Bordeaux, France
| | - Étienne Coutureau
- CNRS, INCIA, UMR 5287, 33076 Bordeaux, France; Université de Bordeaux, INCIA, UMR 5287, 33076 Bordeaux, France
| | - Alain R Marchand
- CNRS, INCIA, UMR 5287, 33076 Bordeaux, France; Université de Bordeaux, INCIA, UMR 5287, 33076 Bordeaux, France.
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211
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Tu PC, Lee YC, Chen YS, Hsu JW, Li CT, Su TP. Network-specific cortico-thalamic dysconnection in schizophrenia revealed by intrinsic functional connectivity analyses. Schizophr Res 2015; 166:137-43. [PMID: 26081977 DOI: 10.1016/j.schres.2015.05.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 04/15/2015] [Accepted: 05/01/2015] [Indexed: 11/29/2022]
Abstract
BACKGROUND Cortico-thalamic connections are thought to be abnormal in schizophrenia due to their important roles in sensory relay and higher cognitive control, both of which are affected by this devastating illness. This study tested the cortico-thalamic dysconnection hypothesis in schizophrenia and further explored cortico-thalamic network properties using functional connectivity MRI (fcMRI). METHODS Forty-eight participants with schizophrenia and 48 healthy controls underwent resting fMRI scans and clinical evaluations. Six a priori cortical regions of interests (ROIs) were used to derive the six networks: dorsal default mode network (dDMN), fronto-parietal network (FPN), cingulo-opercular network (CON), primary sensorimotor network (SM1), primary auditory network (A1) and primary visual network (V1). The cortico-thalamic connectivity for each network was calculated for each participant and then compared between groups. RESULTS A repeated measures analysis of variance (ANOVA) showed significant group×network interactions (F(5, 90)=9.5, P<0.001), which were driven by a significant increase in FC within the SM1 (t(94)=4.1, P<0.001) and A1 (t(94)=4.2, P<0.001) networks in schizophrenics, as well as a significant decrease within the CON (t(94)=-2.8, P=0.04). The cortico-thalamic dysconnection did not correlate with symptom severity, representing a state independent abnormality. CONCLUSION The network analysis indicates that cortico-thalamic dysconnection in schizophrenia involves multiple networks and shows network specific changes. The findings provide support for dysfunctional thalamus-related networks in schizophrenia and further elaborate their network properties.
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Affiliation(s)
- Pei-Chi Tu
- Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei 112, Taiwan; Department of Psychiatry, Taipei Veterans General Hospital, Taipei 112, Taiwan; Institute of Philosophy of Mind and Cognition, National Yang-Ming University, Taipei, Taiwan; Department of Psychiatry, Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Ying-Chiao Lee
- Department of Psychiatry, Taipei Veterans General Hospital, Taipei 112, Taiwan; Department of Psychiatry, Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Ying-Shiue Chen
- Department of Psychiatry, Taipei Veterans General Hospital, Taipei 112, Taiwan; Department of Psychiatry, Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Ju-Wei Hsu
- Department of Psychiatry, Taipei Veterans General Hospital, Taipei 112, Taiwan; Department of Psychiatry, Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Cheng-Ta Li
- Department of Psychiatry, Taipei Veterans General Hospital, Taipei 112, Taiwan; Department of Psychiatry, Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Tung-Ping Su
- Department of Psychiatry, Taipei Veterans General Hospital, Taipei 112, Taiwan; Department of Psychiatry, Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan.
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212
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The role of the thalamus in schizophrenia from a neuroimaging perspective. Neurosci Biobehav Rev 2015; 54:57-75. [DOI: 10.1016/j.neubiorev.2015.01.013] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 12/19/2014] [Accepted: 01/12/2015] [Indexed: 02/06/2023]
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213
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Ackerley R, Kavounoudias A. The role of tactile afference in shaping motor behaviour and implications for prosthetic innovation. Neuropsychologia 2015; 79:192-205. [PMID: 26102191 DOI: 10.1016/j.neuropsychologia.2015.06.024] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 06/02/2015] [Accepted: 06/17/2015] [Indexed: 10/23/2022]
Abstract
The present review focusses on how tactile somatosensory afference is encoded and processed, and how this information is interpreted and acted upon in terms of motor control. We relate the fundamental workings of the sensorimotor system to the rehabilitation of amputees using modern prosthetic interventions. Our sense of touch is central to our everyday lives, from allowing us to manipulate objects accurately to giving us a sense of self-embodiment. There are a variety of specialised cutaneous mechanoreceptive afferents, which differ in terms of type and density according to the skin site. In humans, there is a dense innervation of our hands, which is reflected in their vast over-representation in somatosensory and motor cortical areas. We review the accumulated evidence from animal and human studies about the precise interplay between the somatosensory and motor systems, which is highly integrated in many brain areas and often not separable. The glabrous hand skin provides exquisite, discriminative detail about touch, which is useful for refining movements. When these signals are disrupted, such as through injury or amputation, the consequences are considerable. The development of sensory feedback in prosthetics offers a promising avenue for the full integration of a missing body part. Real-time touch feedback from motor intentions aids in grip control and the ability to distinguish different surfaces, even introducing the possibility of pleasure in artificial touch. Thus, our knowledge from fundamental research into sensorimotor interactions should be used to develop more realistic and integrative prostheses.
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Affiliation(s)
- Rochelle Ackerley
- Department of Physiology, University of Gothenburg, Göteborg, Sweden; Laboratoire Neurosciences Intégratives et Adaptatives (UMR 7260), Aix Marseille Université - CNRS, Marseille, France.
| | - Anne Kavounoudias
- Laboratoire Neurosciences Intégratives et Adaptatives (UMR 7260), Aix Marseille Université - CNRS, Marseille, France
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214
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Balaram P, Isaamullah M, Petry HM, Bickford ME, Kaas JH. Distributions of vesicular glutamate transporters 1 and 2 in the visual system of tree shrews (Tupaia belangeri). J Comp Neurol 2015; 523:1792-808. [PMID: 25521420 DOI: 10.1002/cne.23727] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 12/08/2014] [Accepted: 12/09/2014] [Indexed: 12/13/2022]
Abstract
Vesicular glutamate transporter (VGLUT) proteins regulate the storage and release of glutamate from synapses of excitatory neurons. Two isoforms, VGLUT1 and VGLUT2, are found in most glutamatergic projections across the mammalian visual system, and appear to differentially identify subsets of excitatory projections between visual structures. To expand current knowledge on the distribution of VGLUT isoforms in highly visual mammals, we examined the mRNA and protein expression patterns of VGLUT1 and VGLUT2 in the lateral geniculate nucleus (LGN), superior colliculus, pulvinar complex, and primary visual cortex (V1) in tree shrews (Tupaia belangeri), which are closely related to primates but classified as a separate order (Scandentia). We found that VGLUT1 was distributed in intrinsic and corticothalamic connections, whereas VGLUT2 was predominantly distributed in subcortical and thalamocortical connections. VGLUT1 and VGLUT2 were coexpressed in the LGN and in the pulvinar complex, as well as in restricted layers of V1, suggesting a greater heterogeneity in the range of efferent glutamatergic projections from these structures. These findings provide further evidence that VGLUT1 and VGLUT2 identify distinct populations of excitatory neurons in visual brain structures across mammals. Observed variations in individual projections may highlight the evolution of these connections through the mammalian lineage.
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Affiliation(s)
- P Balaram
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, 37240
| | - M Isaamullah
- School of Medicine, University of Illinois at Chicago, Chicago, Illinois, 60607
| | - H M Petry
- Department of Psychological and Brain Sciences, University of Louisville, Louisville, Kentucky, 40292
| | - M E Bickford
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky, 40292
| | - J H Kaas
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, 37240
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215
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Abstract
Intuition suggests that perception follows sensation and therefore bodily feelings originate in the body. However, recent evidence goes against this logic: interoceptive experience may largely reflect limbic predictions about the expected state of the body that are constrained by ascending visceral sensations. In this Opinion article, we introduce the Embodied Predictive Interoception Coding model, which integrates an anatomical model of corticocortical connections with Bayesian active inference principles, to propose that agranular visceromotor cortices contribute to interoception by issuing interoceptive predictions. We then discuss how disruptions in interoceptive predictions could function as a common vulnerability for mental and physical illness.
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Affiliation(s)
- Lisa Feldman Barrett
- Northeastern University, Department of Psychology, Boston, Massachusetts 02115, USA; and the Massachusetts General Hospital, Department of Psychiatry and the Martinos Center for Biomedical Imaging, Charlestown, Massachusetts 02129, USA
| | - W Kyle Simmons
- Laureate Institute for Brain Research, Tulsa, Oklahoma 74133, USA; and the Faculty of Community Medicine, University of Tulsa, Tulsa, Oklahoma 74104, USA
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216
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Jiang Y, Yampolsky D, Purushothaman G, Casagrande VA. Perceptual decision related activity in the lateral geniculate nucleus. J Neurophysiol 2015; 114:717-35. [PMID: 26019309 DOI: 10.1152/jn.00068.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 05/26/2015] [Indexed: 12/24/2022] Open
Abstract
Fundamental to neuroscience is the understanding of how the language of neurons relates to behavior. In the lateral geniculate nucleus (LGN), cells show distinct properties such as selectivity for particular wavelengths, increments or decrements in contrast, or preference for fine detail versus rapid motion. No studies, however, have measured how LGN cells respond when an animal is challenged to make a perceptual decision using information within the receptive fields of those LGN cells. In this study we measured neural activity in the macaque LGN during a two-alternative, forced-choice (2AFC) contrast detection task or during a passive fixation task and found that a small proportion (13.5%) of single LGN parvocellular (P) and magnocellular (M) neurons matched the psychophysical performance of the monkey. The majority of LGN neurons measured in both tasks were not as sensitive as the monkey. The covariation between neural response and behavior (quantified as choice probability) was significantly above chance during active detection, even when there was no external stimulus. Interneuronal correlations and task-related gain modulations were negligible under the same condition. A bottom-up pooling model that used sensory neural responses to compute perceptual choices in the absence of interneuronal correlations could fully explain these results at the level of the LGN, supporting the hypothesis that the perceptual decision pool consists of multiple sensory neurons and that response fluctuations in these neurons can influence perception.
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Affiliation(s)
- Yaoguang Jiang
- Department of Psychology, Vanderbilt University, Nashville, Tennessee
| | - Dmitry Yampolsky
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee; and
| | - Gopathy Purushothaman
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee; and
| | - Vivien A Casagrande
- Department of Psychology, Vanderbilt University, Nashville, Tennessee; Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee; and Department of Ophthalmology and Visual Sciences, Vanderbilt University, Nashville, Tennessee
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217
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Bastuji H, Frot M, Mazza S, Perchet C, Magnin M, Garcia-Larrea L. Thalamic Responses to Nociceptive-Specific Input in Humans: Functional Dichotomies and Thalamo-Cortical Connectivity. Cereb Cortex 2015; 26:2663-76. [DOI: 10.1093/cercor/bhv106] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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218
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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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219
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Hale JR, Mayhew SD, Mullinger KJ, Wilson RS, Arvanitis TN, Francis ST, Bagshaw AP. Comparison of functional thalamic segmentation from seed-based analysis and ICA. Neuroimage 2015; 114:448-65. [PMID: 25896929 DOI: 10.1016/j.neuroimage.2015.04.027] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 04/02/2015] [Accepted: 04/07/2015] [Indexed: 01/07/2023] Open
Abstract
Information flow between the thalamus and cerebral cortex is a crucial component of adaptive brain function, but the details of thalamocortical interactions in human subjects remain unclear. The principal aim of this study was to evaluate the agreement between functional thalamic network patterns, derived using seed-based connectivity analysis and independent component analysis (ICA) applied separately to resting state functional MRI (fMRI) data from 21 healthy participants. For the seed-based analysis, functional thalamic parcellation was achieved by computing functional connectivity (FC) between thalamic voxels and a set of pre-defined cortical regions. Thalamus-constrained ICA provided an alternative parcellation. Both FC analyses demonstrated plausible and comparable group-level thalamic subdivisions, in agreement with previous work. Quantitative assessment of the spatial overlap between FC thalamic segmentations, and comparison of each to a histological "gold-standard" thalamic atlas and a structurally-defined thalamic atlas, highlighted variations between them and, most notably, differences with both histological and structural results. Whilst deeper understanding of thalamocortical connectivity rests upon identification of features common to multiple non-invasive neuroimaging techniques (e.g. FC, structural connectivity and anatomical localisation of individual-specific nuclei), this work sheds further light on the functional organisation of the thalamus and the varying sensitivities of complementary analyses to resolve it.
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Affiliation(s)
- Joanne R Hale
- School of Psychology, University of Birmingham, Birmingham, United Kingdom.
| | - Stephen D Mayhew
- School of Psychology, University of Birmingham, Birmingham, United Kingdom
| | - Karen J Mullinger
- School of Psychology, University of Birmingham, Birmingham, United Kingdom; Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom
| | - Rebecca S Wilson
- School of Psychology, University of Birmingham, Birmingham, United Kingdom
| | - Theodoros N Arvanitis
- Institute of Digital Healthcare, WMG, University of Warwick, Coventry, United Kingdom
| | - Susan T Francis
- Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom
| | - Andrew P Bagshaw
- School of Psychology, University of Birmingham, Birmingham, United Kingdom
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220
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Nakamura H, Hioki H, Furuta T, Kaneko T. Different cortical projections from three subdivisions of the rat lateral posterior thalamic nucleus: a single-neuron tracing study with viral vectors. Eur J Neurosci 2015; 41:1294-310. [DOI: 10.1111/ejn.12882] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 02/19/2015] [Accepted: 02/26/2015] [Indexed: 12/19/2022]
Affiliation(s)
- Hisashi Nakamura
- Department of Morphological Brain Science; Graduate School of Medicine; Kyoto University; Kyoto 606-8501 Japan
| | - Hiroyuki Hioki
- Department of Morphological Brain Science; Graduate School of Medicine; Kyoto University; Kyoto 606-8501 Japan
| | - Takahiro Furuta
- Department of Morphological Brain Science; Graduate School of Medicine; Kyoto University; Kyoto 606-8501 Japan
| | - Takeshi Kaneko
- Department of Morphological Brain Science; Graduate School of Medicine; Kyoto University; Kyoto 606-8501 Japan
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221
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Petrof I, Viaene AN, Sherman SM. Properties of the primary somatosensory cortex projection to the primary motor cortex in the mouse. J Neurophysiol 2015; 113:2400-7. [PMID: 25632081 PMCID: PMC4416606 DOI: 10.1152/jn.00949.2014] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 01/22/2015] [Indexed: 11/22/2022] Open
Abstract
The primary somatosensory (S1) and primary motor (M1) cortices are reciprocally connected, and their interaction has long been hypothesized to contribute to coordinated motor output. Very little is known, however, about the nature and synaptic properties of the S1 input to M1. Here we wanted to take advantage of a previously developed sensorimotor slice preparation that preserves much of the S1-to-M1 connectivity (Rocco MM, Brumberg JC. J Neurosci Methods 162: 139-147, 2007), as well as available optogenetic methodologies, in order to investigate the synaptic profile of this projection. Our data show that S1 input to pyramidal cells of M1 is highly homogeneous, possesses many features of a "driver" pathway, such as paired-pulse depression and lack of metabotropic glutamate receptor activation, and is mediated through axons that terminate in both small and large synaptic boutons. Our data suggest that S1 provides M1 with afferents that possess synaptic and anatomical characteristics ideal for the delivery of strong inputs that can "drive" postsynaptic M1 cells, thereby potentially affecting their output.
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Affiliation(s)
- Iraklis Petrof
- Department of Neurobiology, University of Chicago, Chicago, Illinois
| | - Angela N Viaene
- Department of Neurobiology, University of Chicago, Chicago, Illinois
| | - S Murray Sherman
- Department of Neurobiology, University of Chicago, Chicago, Illinois
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222
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Poh JS, Li Y, Ratnarajah N, Fortier MV, Chong YS, Kwek K, Saw SM, Gluckman PD, Meaney MJ, Qiu A. Developmental synchrony of thalamocortical circuits in the neonatal brain. Neuroimage 2015; 116:168-76. [PMID: 25812713 DOI: 10.1016/j.neuroimage.2015.03.039] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 02/17/2015] [Accepted: 03/14/2015] [Indexed: 11/15/2022] Open
Abstract
The thalamus is a deep gray matter structure and consists of axonal fibers projecting to the entire cortex, which provide the anatomical support for its sensorimotor and higher-level cognitive functions. There is limited in vivo evidence on the normal thalamocortical development, especially in early life. In this study, we aimed to investigate the developmental patterns of the cerebral cortex, the thalamic substructures, and their connectivity with the cortex in the first few weeks of the postnatal brain. We hypothesized that there is developmental synchrony of the thalamus, its cortical projections, and corresponding target cortical structures. We employed diffusion tensor imaging (DTI) and divided the thalamus into five substructures respectively connecting to the frontal, precentral, postcentral, temporal, and parietal and occipital cortex. T2-weighted magnetic resonance imaging (MRI) was used to measure cortical thickness. We found age-related increases in cortical thickness of bilateral frontal cortex and left temporal cortex in the early postnatal brain. We also found that the development of the thalamic substructures was synchronized with that of their respective thalamocortical connectivity in the first few weeks of the postnatal life. In particular, the right thalamo-frontal substructure had the fastest growth in the early postnatal brain. Our study suggests that the distinct growth patterns of the thalamic substructures are in synchrony with those of the cortex in early life, which may be critical for the development of the cortical and subcortical functional specialization.
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Affiliation(s)
- Joann S Poh
- Department of Biomedical Engineering, National University of Singapore, Singapore; Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore
| | - Yue Li
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Nagulan Ratnarajah
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Marielle V Fortier
- Department of Diagnostic and Interventional Imaging, KK Women's and Children's Hospital, Singapore
| | - Yap-Seng Chong
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore; Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore
| | - Kenneth Kwek
- Department of Maternal Fetal Medicine, KK Women's and Children's Hospital, Singapore
| | - Seang-Mei Saw
- Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore
| | - Peter D Gluckman
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore; Liggins Institute, University of Auckland, Auckland, New Zealand
| | - Michael J Meaney
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore; Ludmer Centre for Neuroinformatics and Mental Health, Douglas Mental Health University Institute, McGill University, Canada; Sackler Program for Epigenetics and Psychobiology, McGill University, Canada
| | - Anqi Qiu
- Department of Biomedical Engineering, National University of Singapore, Singapore; Clinical Imaging Research Centre, National University of Singapore, Singapore; Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore.
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223
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Kipp M, Wagenknecht N, Beyer C, Samer S, Wuerfel J, Nikoubashman O. Thalamus pathology in multiple sclerosis: from biology to clinical application. Cell Mol Life Sci 2015; 72:1127-47. [PMID: 25417212 PMCID: PMC11113280 DOI: 10.1007/s00018-014-1787-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 10/29/2014] [Accepted: 11/17/2014] [Indexed: 10/24/2022]
Abstract
There is a broad consensus that MS represents more than an inflammatory disease: it harbors several characteristic aspects of a classical neurodegenerative disorder, i.e. damage to axons, synapses and nerve cell bodies. While the clinician is equipped with appropriate tools to dampen peripheral cell recruitment and, thus, is able to prevent immune-cell driven relapses, effective therapeutic options to prevent the simultaneously progressing neurodegeneration are still missing. Furthermore, while several sophisticated paraclinical methods exist to monitor the inflammatory-driven aspects of the disease, techniques to monitor progression of early neurodegeneration are still in their infancy and have not been convincingly validated. In this review article, we aim to elaborate why the thalamus with its multiple reciprocal connections is sensitive to pathological processes occurring in different brain regions, thus acting as a "barometer" for diffuse brain parenchymal damage in MS. The thalamus might be, thus, an ideal region of interest to test the effectiveness of new neuroprotective MS drugs. Especially, we will address underlying pathological mechanisms operant during thalamus degeneration in MS, such as trans-neuronal or Wallerian degeneration. Furthermore, we aim at giving an overview about different paraclinical methods used to estimate the extent of thalamic pathology in MS patients, and we discuss their limitations. Finally, thalamus involvement in different MS animal models will be described, and their relevance for the design of preclinical trials elaborated.
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Affiliation(s)
- Markus Kipp
- Institute of Neuroanatomy, Faculty of Medicine, RWTH Aachen University, Wendlingweg 2, 52074, Aachen, Germany,
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224
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Target-specific properties of thalamocortical synapses onto layer 4 of mouse primary visual cortex. J Neurosci 2015; 34:15455-65. [PMID: 25392512 DOI: 10.1523/jneurosci.2595-14.2014] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In primary sensory cortices, thalamocortical (TC) inputs can directly activate excitatory and inhibitory neurons. In vivo experiments in the main input layer (L4) of primary visual cortex (V1) have shown that excitatory and inhibitory neurons have different tuning properties. The different functional properties may arise from distinct intrinsic properties of L4 neurons, but could also depend on cell type-specific properties of the synaptic inputs from the lateral geniculate nucleus of the thalamus (LGN) onto L4 neurons. While anatomical studies identified LGN inputs onto both excitatory and inhibitory neurons in V1, their synaptic properties have not been investigated. Here we used an optogenetic approach to selectively activate LGN terminal fields in acute coronal slices containing V1, and recorded monosynaptic currents from excitatory and inhibitory neurons in L4. LGN afferents made monosynaptic connections with pyramidal (Pyr) and fast-spiking (FS) neurons. TC EPSCs on FS neurons were larger and showed steeper short-term depression in response to repetitive stimulation than those on Pyr neurons. LGN inputs onto Pyr and FS neurons also differed in postsynaptic receptor composition and organization of presynaptic release sites. Together, our results demonstrate that LGN input onto L4 neurons in mouse V1 have target-specific presynaptic and postsynaptic properties. Distinct mechanisms of activation of feedforward excitatory and inhibitory neurons in the main input layer of V1 are likely to endow neurons with different response properties to incoming visual stimuli.
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225
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Abstract
The main impetus for a mini-symposium on corticothalamic interrelationships was the recent number of studies highlighting the role of the thalamus in aspects of cognition beyond sensory processing. The thalamus contributes to a range of basic cognitive behaviors that include learning and memory, inhibitory control, decision-making, and the control of visual orienting responses. Its functions are deeply intertwined with those of the better studied cortex, although the principles governing its coordination with the cortex remain opaque, particularly in higher-level aspects of cognition. How should the thalamus be viewed in the context of the rest of the brain? Although its role extends well beyond relaying of sensory information from the periphery, the main function of many of its subdivisions does appear to be that of a relay station, transmitting neural signals primarily to the cerebral cortex from a number of brain areas. In cognition, its main contribution may thus be to coordinate signals between diverse regions of the telencephalon, including the neocortex, hippocampus, amygdala, and striatum. This central coordination is further subject to considerable extrinsic control, for example, inhibition from the basal ganglia, zona incerta, and pretectal regions, and chemical modulation from ascending neurotransmitter systems. What follows is a brief review on the role of the thalamus in aspects of cognition and behavior, focusing on a summary of the topics covered in a mini-symposium held at the Society for Neuroscience meeting, 2014.
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226
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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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227
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Warner C, Kwan W, Wright D, Johnston L, Egan G, Bourne J. Preservation of Vision by the Pulvinar following Early-Life Primary Visual Cortex Lesions. Curr Biol 2015; 25:424-34. [PMID: 25601551 DOI: 10.1016/j.cub.2014.12.028] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 11/14/2014] [Accepted: 12/05/2014] [Indexed: 10/24/2022]
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228
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Holtz SL, Fu A, Loflin W, Corson JA, Erisir A. Morphology and connectivity of parabrachial and cortical inputs to gustatory thalamus in rats. J Comp Neurol 2015; 523:139-61. [PMID: 25186035 PMCID: PMC4232453 DOI: 10.1002/cne.23673] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 08/24/2014] [Accepted: 08/27/2014] [Indexed: 11/07/2022]
Abstract
The ventroposterior medialis parvocellularis (VPMpc) nucleus of the thalamus, the thalamic relay nucleus for gustatory sensation, receives primary input from the parabrachial nucleus, and projects to the insular cortex. To reveal the unique properties of the gustatory thalamus in comparison with archetypical sensory relay nuclei, this study examines the morphology of synaptic circuitry in the VPMpc, focusing on parabrachiothalamic driver input and corticothalamic feedback. Anterogradely visualized parabrachiothalamic fibers in the VPMpc bear large swellings. At electron microscope resolution, parabrachiothalamic axons are myelinated and make large boutons, forming multiple asymmetric, adherent, and perforated synapses onto large-caliber dendrites and dendrite initial segments. Labeled boutons contain dense-core vesicles, and they resemble a population of terminals within the VPMpc containing calcitonin gene-related peptide. As is typical of primary inputs to other thalamic nuclei, parabrachiothalamic terminals are over five times larger than other inputs, while constituting only 2% of all synapses. Glomeruli and triadic arrangements, characteristic features of other sensory thalamic nuclei, are not encountered. As revealed by anterograde tracer injections into the insular cortex, corticothalamic projections in the VPMpc form a dense network of fine fibers bearing small boutons. Corticothalamic terminals within the VPMpc were also observed to synapse on cells that were retrogradely filled from the same injections. The results constitute an initial survey describing unique anatomical properties of the rodent gustatory thalamus.
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Affiliation(s)
- Stephen L. Holtz
- Department of Psychology, University of Virginia, Charlottesville VA 22904-4400, USA
| | - Anqi Fu
- Department of Psychology, University of Virginia, Charlottesville VA 22904-4400, USA
| | - Wyatt Loflin
- Department of Psychology, University of Virginia, Charlottesville VA 22904-4400, USA
| | - James A. Corson
- Department of Psychology, University of Virginia, Charlottesville VA 22904-4400, USA
| | - Alev Erisir
- Department of Psychology, University of Virginia, Charlottesville VA 22904-4400, USA
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229
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Jastreboff AM, Sinha R, Lacadie CM, Balodis IM, Sherwin R, Potenza MN. Blunted striatal responses to favorite-food cues in smokers. Drug Alcohol Depend 2015; 146:103-6. [PMID: 25444233 PMCID: PMC4272899 DOI: 10.1016/j.drugalcdep.2014.09.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 08/11/2014] [Accepted: 09/05/2014] [Indexed: 12/18/2022]
Abstract
BACKGROUND Although tobacco-smoking is associated with relatively leaner body mass and smoking cessation with weight gain, the brain mechanisms underlying these relationships are not well understood. Smokers compared to non-smokers have shown diminished neural responses to non-tobacco rewarding stimuli (e.g., monetary rewards), but brain responses to favorite-food cues have not been investigated relative to smoking status. We hypothesized that smokers would exhibit diminished neural responses compared to non-smokers in response to favorite-food cues in motivation-reward and emotion-regulating regions of the brain. METHODS Twenty-three smokers and 23 non-smokers matched based on body mass index (BMI), age, and gender listened to personalized favorite-food cue, stress, and neutral-relaxing audiotapes during fMRI. RESULTS During favorite-food cue exposure, smokers versus non-smokers exhibited diminished activations in the caudate, putamen, insula, and thalamus. Neural responses during stress and neutral-relaxing conditions were similar across groups. Subjective food-craving ratings were similar across groups. CONCLUSIONS The relatively diminished neural responses to favorite-food cues in smokers may contribute to lower BMI.
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Affiliation(s)
- Ania M. Jastreboff
- Department of Internal Medicine, Division of Endocrinology, Yale University School of Medicine, New Haven, CT
| | - Rajita Sinha
- Department of Psychiatry Yale University School of Medicine, New Haven, CT,Child Study Center, Yale University School of Medicine, New Haven, CT
| | - Cheryl M. Lacadie
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT
| | - Iris M. Balodis
- Department of Psychiatry Yale University School of Medicine, New Haven, CT
| | - Robert Sherwin
- Department of Internal Medicine, Division of Endocrinology, Yale University School of Medicine, New Haven, CT
| | - Marc N. Potenza
- Department of Psychiatry Yale University School of Medicine, New Haven, CT,Child Study Center, Yale University School of Medicine, New Haven, CT,Department of Neurobiology, Yale University School of Medicine, New Haven, CT
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230
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Vázquez-García M, Wallman MJ, Timofeev I. Somatotopic organization of ferret thalamus. Front Integr Neurosci 2014; 8:90. [PMID: 25484859 PMCID: PMC4240062 DOI: 10.3389/fnint.2014.00090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 11/06/2014] [Indexed: 11/23/2022] Open
Abstract
The stereotaxic reference marks of ferret skull have large variability and the reference point for stereotaxic experiments in ferret brain is difficult to define. Here, using extracellular single-unit recordings, we studied the somatotopic organization of cutaneous receptive fields in the ventroposterior medial (VPM) and the ventral posterolateral (VPL) nuclei of the ferret thalamus. The mechanical stimulation of the skin was done through air puffs. The skull was positioned according to Horsley-Clarke coordinate system. Most of the neurons responding to face skin stimulation were located +7–+9 mm anterior, 2–3.9 mm lateral and 7–9.6 mm from cortical surface, whereas those responding to body skin stimulation were located +7–+10 mm anterior, 3.3–5.5 mm lateral and 6.7–10 mm from cortical surface. Out of 90 thalamic neurons recorded in this study, 58 responded to the body and the other neurons to the face stimulation. All neurons responded with spikes to stimulus onset, 37% of neurons responded only to stimuli onset and offset and 22% neurons fired tonically throughout stimulating epoch. The whiskers representation was located in the middle of the VPM nucleus, whereas those of the tongue, nose, bridge of the nose, supraorbital areas, upper and lower lips, and lower jaw were surrounding the whiskers representation. Within the VPL nucleus there was a clear topological correspondence from forelimb to hindlimb in the medial-to-lateral direction. Our findings indicate the whiskers representation in VPM or the forelimb-hindlimb representation in the VPL nucleus can be considered as a reliable reference in the ferret thalamus.
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Affiliation(s)
- Mario Vázquez-García
- Le Centre de Recherche de L'Institut Universitaire en Santé Mentale de Québec Québec, QC, Canada ; Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México México, D.F., México
| | - Marie-Josée Wallman
- Le Centre de Recherche de L'Institut Universitaire en Santé Mentale de Québec Québec, QC, Canada
| | - Igor Timofeev
- Le Centre de Recherche de L'Institut Universitaire en Santé Mentale de Québec Québec, QC, Canada ; Department of Psychiatry and Neuroscience, Université Laval Québec, Canada
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Schilling TM, Larra MF, Deuter CE, Blumenthal TD, Schächinger H. Rapid cortisol enhancement of psychomotor and startle reactions to side-congruent stimuli in a focused cross-modal choice reaction time paradigm. Eur Neuropsychopharmacol 2014; 24:1828-35. [PMID: 25262177 DOI: 10.1016/j.euroneuro.2014.09.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 08/18/2014] [Accepted: 09/03/2014] [Indexed: 10/24/2022]
Abstract
The stress hormone cortisol has been shown to affect hemodynamic activity of human brain structures, presumably via a nongenomic mechanism. However, behavioral implications of this finding remain unknown. In a placebo-controlled, blinded, cross-over design the rapid effects of IV hydrocortisone (5mg) on cross-modal integration of simultaneous, unilateral visual and acoustic signals in a challenging startle and reaction time (RT) paradigm were studied. On two separate days 1 week apart, 24 male volunteers responded by button push to either up- or down pointing triangles presented in random sequence in the periphery of one of the visual hemi-fields. Visual targets were accompanied by unilateral acoustic startle noise bursts, presented at the same or opposite side. Saccadic latency, manual RT, and startle eye blink responses were recorded. Faster manual reactions and increased startle eye blink responses were observed 11-20 min after hydrocortisone administration when visual targets and unilateral acoustic startle noises were presented in the same sensory hemi-field, but not when presented in opposite sensory hemi-fields. Our results suggest that a nongenomic, cortisol-sensitive mechanism enhances psychomotor and startle reactions when stimuli occur in the same sensory hemi-field. Such basic cognitive effects of cortisol may serve rapid adaptation and protection against danger stimuli in stressful contexts.
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Affiliation(s)
- Thomas M Schilling
- Institute of Psychobiology, Division of Clinical Psychophysiology, University of Trier, Johanniterufer 15, D-54290 Trier, Germany.
| | - Mauro F Larra
- Institute of Psychobiology, Division of Clinical Psychophysiology, University of Trier, Johanniterufer 15, D-54290 Trier, Germany
| | - Christian E Deuter
- Institute of Psychobiology, Division of Clinical Psychophysiology, University of Trier, Johanniterufer 15, D-54290 Trier, Germany
| | - Terry D Blumenthal
- Department of Psychology, Wake Forest University, Winston-Salem, NC 27109, USA
| | - Hartmut Schächinger
- Institute of Psychobiology, Division of Clinical Psychophysiology, University of Trier, Johanniterufer 15, D-54290 Trier, Germany
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232
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Jastreboff AM, Lacadie C, Seo D, Kubat J, Van Name MA, Giannini C, Savoye M, Constable RT, Sherwin RS, Caprio S, Sinha R. Leptin is associated with exaggerated brain reward and emotion responses to food images in adolescent obesity. Diabetes Care 2014; 37:3061-8. [PMID: 25139883 PMCID: PMC4207200 DOI: 10.2337/dc14-0525] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE In the U.S., an astonishing 12.5 million children and adolescents are now obese, predisposing 17% of our nation's youth to metabolic complications of obesity, such as type 2 diabetes (T2D). Adolescent obesity has tripled over the last three decades in the setting of food advertising directed at children. Obese adults exhibit increased brain responses to food images in motivation-reward pathways. These neural alterations may be attributed to obesity-related metabolic changes, which promote food craving and high-calorie food (HCF) consumption. It is not known whether these metabolic changes affect neural responses in the adolescent brain during a crucial period for establishing healthy eating behaviors. RESEARCH DESIGN AND METHODS Twenty-five obese (BMI 34.4 kg/m2, age 15.7 years) and fifteen lean (BMI 20.96 kg/m2, age 15.5 years) adolescents underwent functional MRI during exposure to HCF, low-calorie food (LCF), and nonfood (NF) visual stimuli 2 h after isocaloric meal consumption. RESULTS Brain responses to HCF relative to NF cues increased in obese versus lean adolescents in striatal-limbic regions (i.e., putamen/caudate, insula, amygdala) (P < 0.05, family-wise error [FWE]), involved in motivation-reward and emotion processing. Higher endogenous leptin levels correlated with increased neural activation to HCF images in all subjects (P < 0.05, FWE). CONCLUSIONS This significant association between higher circulating leptin and hyperresponsiveness of brain motivation-reward regions to HCF images suggests that dysfunctional leptin signaling may contribute to the risk of overconsumption of these foods, thus further predisposing adolescents to the development of obesity and T2D.
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Affiliation(s)
- Ania M Jastreboff
- Division of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT Division of Pediatric Endocrinology, Department of Pediatrics, Yale University School of Medicine, New Haven, CT
| | - Cheryl Lacadie
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT
| | - Dongju Seo
- Department of Psychiatry, Yale University School of Medicine, Yale Stress Center, New Haven, CT
| | - Jessica Kubat
- Division of Pediatric Endocrinology, Department of Pediatrics, Yale University School of Medicine, New Haven, CT
| | - Michelle A Van Name
- Division of Pediatric Endocrinology, Department of Pediatrics, Yale University School of Medicine, New Haven, CT
| | - Cosimo Giannini
- Department of Pediatric, University of Chieti, Chieti, Italy
| | - Mary Savoye
- Division of Pediatric Endocrinology, Department of Pediatrics, Yale University School of Medicine, New Haven, CT
| | - R Todd Constable
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT
| | - Robert S Sherwin
- Division of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - Sonia Caprio
- Division of Pediatric Endocrinology, Department of Pediatrics, Yale University School of Medicine, New Haven, CT
| | - Rajita Sinha
- Department of Psychiatry, Yale University School of Medicine, Yale Stress Center, New Haven, CT Department of Neurobiology, Yale University School of Medicine, New Haven, CT Child Study Center, Yale University School of Medicine, New Haven, CT
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233
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Tewarie P, Schoonheim MM, Schouten DI, Polman CH, Balk LJ, Uitdehaag BMJ, Geurts JJG, Hillebrand A, Barkhof F, Stam CJ. Functional brain networks: linking thalamic atrophy to clinical disability in multiple sclerosis, a multimodal fMRI and MEG study. Hum Brain Mapp 2014; 36:603-18. [PMID: 25293505 DOI: 10.1002/hbm.22650] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 09/29/2014] [Indexed: 01/04/2023] Open
Abstract
Thalamic atrophy is known to be one of the most important predictors for clinical dysfunction in multiple sclerosis (MS). As the thalamus is highly connected to many cortical areas, this suggests that thalamic atrophy is associated with disruption of cortical functional networks. We investigated this thalamo-cortical system to explain the presence of physical and cognitive problems in MS. Functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) were performed in 86 MS patients and 21 healthy subjects. We computed cortical functional networks for fMRI and MEG by respectively the Pearson's correlation coefficient and the phase lag index using the same automated anatomical labeling atlas for both modalities. Thalamo-cortical functional connectivity was only estimated using fMRI. We computed conventional network metrics such as clustering coefficient and path length and analyzed the minimum spanning tree (MST), a subnetwork and backbone of the original network. MS patients showed reduced thalamic volumes and increased thalamo-cortical connectivity. MEG cortical functional networks showed a lower level of integration in MS in terms of the MST, whereas fMRI cortical networks did not differ between groups. Lower integration of MEG cortical functional networks was both related to thalamic atrophy as well as to increased thalamo-cortical functional connectivity in fMRI and to worse cognitive and clinical status. This study demonstrated for the first time that thalamic atrophy is associated with global disruption of cortical functional networks in MS and this global disruption of network activity was related to worse cognitive and clinical function in MS. Hum Brain Mapp 36:603-618, 2015. © 2014 Wiley Periodicals, Inc.
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Affiliation(s)
- Prejaas Tewarie
- Department of Neurology, VU University Medical Center, Amsterdam, The Netherlands
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234
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Palm G, Knoblauch A, Hauser F, Schüz A. Cell assemblies in the cerebral cortex. BIOLOGICAL CYBERNETICS 2014; 108:559-572. [PMID: 24692024 DOI: 10.1007/s00422-014-0596-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 02/27/2014] [Indexed: 06/03/2023]
Abstract
Donald Hebb's concept of cell assemblies is a physiology-based idea for a distributed neural representation of behaviorally relevant objects, concepts, or constellations. In the late 70s Valentino Braitenberg started the endeavor to spell out the hypothesis that the cerebral cortex is the structure where cell assemblies are formed, maintained and used, in terms of neuroanatomy (which was his main concern) and also neurophysiology. This endeavor has been carried on over the last 30 years corroborating most of his findings and interpretations. This paper summarizes the present state of cell assembly theory, realized in a network of associative memories, and of the anatomical evidence for its location in the cerebral cortex.
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Affiliation(s)
- Günther Palm
- Institute of Neural Information Processing, University of Ulm, 89069 , Ulm, Germany,
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235
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Delli Pizzi S, Franciotti R, Taylor JP, Thomas A, Tartaro A, Onofrj M, Bonanni L. Thalamic Involvement in Fluctuating Cognition in Dementia with Lewy Bodies: Magnetic Resonance Evidences. Cereb Cortex 2014; 25:3682-9. [PMID: 25260701 PMCID: PMC4585510 DOI: 10.1093/cercor/bhu220] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Dementia with Lewy bodies (DLB) is characterized by fluctuation in cognition and attention. Thalamocortical connectivity and integrity of thalami are central to attentional function. We hypothesize that DLB patients with marked and frequent fluctuating cognition (flCog) have a loss of thalamocortical connectivity, an intrinsic disruption to thalamic structure and imbalances in thalamic neurotransmitter levels. To test this, magnetic resonance imaging (MRI), diffusion tensor imaging (DTI) and proton MR spectroscopy on thalami were performed on 16 DLB, 16 Alzheimer's disease (AD) and 13 healthy subjects. MRI and DTI were combined to subdivide thalami according to their cortical connectivity and to investigate microstructural changes in connectivity-defined thalamic regions. Compared with controls, lower N-acetyl-aspartate/total creatine (NAA/tCr) and higher total choline/total creatine (tCho/tCr) values were observed within thalami of DLB patients. tCho/tCr increase was found within right thalamus of DLB patients as compared with AD. This increase correlated with severity and frequency of flCog. As compared with controls, DLB patients showed bilateral damage within thalamic regions projecting to prefrontal and parieto-occipital cortices, whereas AD patients showed bilateral alteration within thalamic region projecting to temporal cortex. We posit that microstructural thalamic damage and cholinergic imbalance may be central to the etiology of flCog in DLB.
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Affiliation(s)
- Stefano Delli Pizzi
- Department of Neuroscience, Imaging and Clinical Sciences Aging Research Centre, Ce.S.I. and Institute for Advanced Biomedical Technologies (ITAB), "G. d'Annunzio" University, Chieti, Italy
| | - Raffaella Franciotti
- Department of Neuroscience, Imaging and Clinical Sciences Aging Research Centre, Ce.S.I. and Institute for Advanced Biomedical Technologies (ITAB), "G. d'Annunzio" University, Chieti, Italy
| | - John-Paul Taylor
- Institute for Ageing and Health, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK
| | - Astrid Thomas
- Department of Neuroscience, Imaging and Clinical Sciences Aging Research Centre, Ce.S.I. and
| | - Armando Tartaro
- Department of Neuroscience, Imaging and Clinical Sciences Institute for Advanced Biomedical Technologies (ITAB), "G. d'Annunzio" University, Chieti, Italy
| | - Marco Onofrj
- Department of Neuroscience, Imaging and Clinical Sciences Aging Research Centre, Ce.S.I. and
| | - Laura Bonanni
- Department of Neuroscience, Imaging and Clinical Sciences Aging Research Centre, Ce.S.I. and
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236
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Abstract
What is the relationship between brain and behavior? The answer to this question necessitates characterizing the mapping between structure and function. The aim of this paper is to discuss broad issues surrounding the link between structure and function in the brain that will motivate a network perspective to understanding this question. However, as others in the past, I argue that a network perspective should supplant the common strategy of understanding the brain in terms of individual regions. Whereas this perspective is needed for a fuller characterization of the mind-brain, it should not be viewed as panacea. For one, the challenges posed by the many-to-many mapping between regions and functions is not dissolved by the network perspective. Although the problem is ameliorated, one should not anticipate a one-to-one mapping when the network approach is adopted. Furthermore, decomposition of the brain network in terms of meaningful clusters of regions, such as the ones generated by community-finding algorithms, does not by itself reveal "true" subnetworks. Given the hierarchical and multi-relational relationship between regions, multiple decompositions will offer different "slices" of a broader landscape of networks within the brain. Finally, I described how the function of brain regions can be characterized in a multidimensional manner via the idea of diversity profiles. The concept can also be used to describe the way different brain regions participate in networks.
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Affiliation(s)
- Luiz Pessoa
- University of Maryland, College Park, United States
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237
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Shostak Y, Wenger A, Mavity-Hudson J, Casagrande VA. Metabotropic glutamate receptor 5 shows different patterns of localization within the parallel visual pathways in macaque and squirrel monkeys. Eye Brain 2014; 6:29-43. [PMID: 25774086 PMCID: PMC4356996 DOI: 10.2147/eb.s51817] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Glutamate is used as an excitatory neurotransmitter by the koniocellular (K), magnocellular (M), and parvocellular (P) pathways to transfer signals from the primate lateral geniculate nucleus (LGN) to primary visual cortex (V1). Glutamate acts through both fast ionotropic receptors, which appear to carry the main sensory message, and slower, modulatory metabotropic receptors (mGluRs). In this study, we asked whether mGluR5 relates in distinct ways to the K, M, and P LGN axons in V1. To answer this question, we used light microscopic immunocytochemistry and preembedding electron microscopic immunogold labeling to determine the localization of mGluR5 within the layers of V1 in relation to the K, M, and P pathways in macaque and squirrel monkeys. These pathways were labeled separately via wheat germ agglutinin-horseradish peroxidase (WGA-HRP) injections targeting the LGN layers. mGluR5 is of interest because it: 1) has been shown to be expressed in the thalamic input layers; 2) appears to be responsible for some types of oscillatory firing, which could be important in the binding of visual features; and 3) has been associated with a number of sensory-motor gating-related pathologies, including schizophrenia and autism. Our results demonstrated the presence of mGluR5 in the neuropil of all V1 layers. This protein was lowest in IVCα (M input) and the infragranular layers. In layer IVC, mGluR5 also was found postsynaptic to about 30% of labeled axons, but the distribution was uneven, such that postsynaptic mGluR5 label tended to occur opposite smaller (presumed P), and not larger (presumed M) axon terminals. Only in the K pathway in layer IIIB, however, was mGluR5 always found in the axon terminals themselves. The presence of mGluR5 in K axons and not in M and P axons, and the presence of mGluR5 postsynaptic mainly to smaller P and not larger M axons suggest that the response to the release of glutamate is modulated in distinct ways within and between the parallel visual pathways of primates.
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Affiliation(s)
- Yuri Shostak
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA ; Foreign Trade Unitary Enterprise, Minsk, Belarus
| | - Ashley Wenger
- Undergraduate Neuroscience Program, Vanderbilt University, Nashville, TN, USA
| | - Julia Mavity-Hudson
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Vivien A Casagrande
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA ; Department of Psychology, Vanderbilt University, Nashville, TN, USA ; Department of Ophthalmology and Visual Sciences, Vanderbilt University, Nashville, TN, USA
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238
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Abstract
Although commonly viewed as a sensory information relay center, the thalamus has been increasingly recognized as an essential node in various higher-order cognitive circuits, and the underlying thalamocortical interaction mechanism has attracted increasing scientific interest. However, the development of thalamocortical connections and how such development relates to cognitive processes during the earliest stages of life remain largely unknown. Leveraging a large human pediatric sample (N = 143) with longitudinal resting-state fMRI scans and cognitive data collected during the first 2 years of life, we aimed to characterize the age-dependent development of thalamocortical connectivity patterns by examining the functional relationship between the thalamus and nine cortical functional networks and determine the correlation between thalamocortical connectivity and cognitive performance at ages 1 and 2 years. Our results revealed that the thalamus-sensorimotor and thalamus-salience connectivity networks were already present in neonates, whereas the thalamus-medial visual and thalamus-default mode network connectivity emerged later, at 1 year of age. More importantly, brain-behavior analyses based on the Mullen Early Learning Composite Score and visual-spatial working memory performance measured at 1 and 2 years of age highlighted significant correlations with the thalamus-salience network connectivity. These results provide new insights into the understudied early functional brain development process and shed light on the behavioral importance of the emerging thalamocortical connectivity during infancy.
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239
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Tessa C, Lucetti C, Giannelli M, Diciotti S, Poletti M, Danti S, Baldacci F, Vignali C, Bonuccelli U, Mascalchi M, Toschi N. Progression of brain atrophy in the early stages of Parkinson's disease: a longitudinal tensor-based morphometry study in de novo patients without cognitive impairment. Hum Brain Mapp 2014; 35:3932-44. [PMID: 24453162 PMCID: PMC6868950 DOI: 10.1002/hbm.22449] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 11/06/2013] [Accepted: 11/29/2013] [Indexed: 11/11/2022] Open
Abstract
The presence of brain atrophy and its progression in early Parkinson's disease (PD) are still a matter of debate, particularly in patients without cognitive impairment. The aim of this longitudinal study was to assess whether PD patients who remain cognitively intact develop progressive atrophic changes in the early stages of the disease. For this purpose, we employed high-resolution T1-weighted MR imaging to compare 22 drug-naïve de novo PD patients without cognitive impairment to 17 age-matched control subjects, both at baseline and at three-year follow-up. We used tensor-based morphometry to explore the presence of atrophic changes at baseline and to compute yearly atrophy rates, after which we performed voxel-wise group comparisons using threshold-free cluster enhancement. At baseline, we did not observe significant differences in regional atrophy in PD patients with respect to control subjects. In contrast, PD patients showed significantly higher yearly atrophy rates in the prefrontal cortex, anterior cingulum, caudate nucleus, and thalamus when compared to control subjects. Our results indicate that even cognitively preserved PD patients show progressive cortical and subcortical atrophic changes in regions related to cognitive functions and that these changes are already detectable in the early stages of the disease.
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Affiliation(s)
- Carlo Tessa
- Division of RadiologyVersilia Hospital, AUSL 12 Viareggio, Lido di Camaiore (Lu)Italy
| | - Claudio Lucetti
- Division of NeurologyVersilia Hospital, AUSL 12 Viareggio, Lido di Camaiore (Lu)Italy
| | - Marco Giannelli
- Unit of Medical PhysicsPisa University Hospital “Azienda Ospedaliero‐Universitaria Pisana”PisaItaly
| | - Stefano Diciotti
- Quantitative and Functional Neuroradiology Research UnitDepartment of Experimental and Clinical Biomedical SciencesUniversity of FlorenceFlorenceItaly
| | - Michele Poletti
- Department of Mental Health and Pathological AddictionAUSL Reggio EmiliaReggio EmiliaItaly
| | - Sabrina Danti
- Division of PsychologyVersilia Hospital, AUSL 12 ViareggioLido di Camaiore (Lu)Italy
| | | | - Claudio Vignali
- Division of RadiologyVersilia Hospital, AUSL 12 Viareggio, Lido di Camaiore (Lu)Italy
| | | | - Mario Mascalchi
- Quantitative and Functional Neuroradiology Research UnitDepartment of Experimental and Clinical Biomedical SciencesUniversity of FlorenceFlorenceItaly
| | - Nicola Toschi
- Medical Physics SectionDepartment of Biomedicine and PreventionFaculty of MedicineUniversity of Rome “Tor Vergata”RomeItaly
- Department of RadiologyAthinoula A. Martinos Center for Biomedical ImagingBostonMassachusetts
- Harvard Medical SchoolBostonMassachusetts
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240
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Hitier M, Besnard S, Smith PF. Vestibular pathways involved in cognition. Front Integr Neurosci 2014; 8:59. [PMID: 25100954 PMCID: PMC4107830 DOI: 10.3389/fnint.2014.00059] [Citation(s) in RCA: 209] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 06/30/2014] [Indexed: 01/30/2023] Open
Abstract
Recent discoveries have emphasized the role of the vestibular system in cognitive processes such as memory, spatial navigation and bodily self-consciousness. A precise understanding of the vestibular pathways involved is essential to understand the consequences of vestibular diseases for cognition, as well as develop therapeutic strategies to facilitate recovery. The knowledge of the “vestibular cortical projection areas”, defined as the cortical areas activated by vestibular stimulation, has dramatically increased over the last several years from both anatomical and functional points of view. Four major pathways have been hypothesized to transmit vestibular information to the vestibular cortex: (1) the vestibulo-thalamo-cortical pathway, which probably transmits spatial information about the environment via the parietal, entorhinal and perirhinal cortices to the hippocampus and is associated with spatial representation and self-versus object motion distinctions; (2) the pathway from the dorsal tegmental nucleus via the lateral mammillary nucleus, the anterodorsal nucleus of the thalamus to the entorhinal cortex, which transmits information for estimations of head direction; (3) the pathway via the nucleus reticularis pontis oralis, the supramammillary nucleus and the medial septum to the hippocampus, which transmits information supporting hippocampal theta rhythm and memory; and (4) a possible pathway via the cerebellum, and the ventral lateral nucleus of the thalamus (perhaps to the parietal cortex), which transmits information for spatial learning. Finally a new pathway is hypothesized via the basal ganglia, potentially involved in spatial learning and spatial memory. From these pathways, progressively emerges the anatomical network of vestibular cognition.
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Affiliation(s)
- Martin Hitier
- Inserm, U 1075 COMETE Caen, France ; Department of Pharmacology and Toxicology, Brain Health Research Center, University of Otago Dunedin, New Zealand ; Department of Anatomy, UNICAEN Caen, France ; Department of Otolaryngology Head and Neck Surgery, CHU de Caen Caen, France
| | | | - Paul F Smith
- Department of Pharmacology and Toxicology, Brain Health Research Center, University of Otago Dunedin, New Zealand
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241
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Wilkinson N, Paikan A, Gredebäck G, Rea F, Metta G. Staring us in the face? An embodied theory of innate face preference. Dev Sci 2014; 17:809-25. [PMID: 24946990 DOI: 10.1111/desc.12159] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 11/01/2013] [Indexed: 11/28/2022]
Abstract
Human expertise in face perception grows over development, but even within minutes of birth, infants exhibit an extraordinary sensitivity to face-like stimuli. The dominant theory accounts for innate face detection by proposing that the neonate brain contains an innate face detection device, dubbed 'Conspec'. Newborn face preference has been promoted as some of the strongest evidence for innate knowledge, and forms a canonical stage for the modern form of the nature-nurture debate in psychology. Interpretation of newborn face preference results has concentrated on monocular stimulus properties, with little mention or focused investigation of potential binocular involvement. However, the question of whether and how newborns integrate the binocular visual streams bears directly on the generation of observable visual preferences. In this theoretical paper, we employ a synthetic approach utilizing robotic and computational models to draw together the threads of binocular integration and face preference in newborns, and demonstrate cases where the former may explain the latter. We suggest that a system-level view considering the binocular embodiment of newborn vision may offer a mutually satisfying resolution to some long-running arguments in the polarizing debate surrounding the existence and causal structure of newborns' 'innate knowledge' of faces.
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Affiliation(s)
- Nick Wilkinson
- iCub Facility, Istituto Italiano di Tecnologia, Genova, Italy
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242
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Nicotinic acetylcholine receptors in attention circuitry: the role of layer VI neurons of prefrontal cortex. Cell Mol Life Sci 2014; 71:1225-44. [PMID: 24122021 PMCID: PMC3949016 DOI: 10.1007/s00018-013-1481-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 09/03/2013] [Accepted: 09/16/2013] [Indexed: 12/15/2022]
Abstract
Cholinergic modulation of prefrontal cortex is essential for attention. In essence, it focuses the mind on relevant, transient stimuli in support of goal-directed behavior. The excitation of prefrontal layer VI neurons through nicotinic acetylcholine receptors optimizes local and top-down control of attention. Layer VI of prefrontal cortex is the origin of a dense feedback projection to the thalamus and is one of only a handful of brain regions that express the α5 nicotinic receptor subunit, encoded by the gene chrna5. This accessory nicotinic receptor subunit alters the properties of high-affinity nicotinic receptors in layer VI pyramidal neurons in both development and adulthood. Studies investigating the consequences of genetic deletion of α5, as well as other disruptions to nicotinic receptors, find attention deficits together with altered cholinergic excitation of layer VI neurons and aberrant neuronal morphology. Nicotinic receptors in prefrontal layer VI neurons play an essential role in focusing attention under challenging circumstances. In this regard, they do not act in isolation, but rather in concert with cholinergic receptors in other parts of prefrontal circuitry. This review urges an intensification of focus on the cellular mechanisms and plasticity of prefrontal attention circuitry. Disruptions in attention are one of the greatest contributing factors to disease burden in psychiatric and neurological disorders, and enhancing attention may require different approaches in the normal and disordered prefrontal cortex.
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243
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Schepers IM, Yoshor D, Beauchamp MS. Electrocorticography Reveals Enhanced Visual Cortex Responses to Visual Speech. Cereb Cortex 2014; 25:4103-10. [PMID: 24904069 DOI: 10.1093/cercor/bhu127] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Human speech contains both auditory and visual components, processed by their respective sensory cortices. We test a simple model in which task-relevant speech information is enhanced during cortical processing. Visual speech is most important when the auditory component is uninformative. Therefore, the model predicts that visual cortex responses should be enhanced to visual-only (V) speech compared with audiovisual (AV) speech. We recorded neuronal activity as patients perceived auditory-only (A), V, and AV speech. Visual cortex showed strong increases in high-gamma band power and strong decreases in alpha-band power to V and AV speech. Consistent with the model prediction, gamma-band increases and alpha-band decreases were stronger for V speech. The model predicts that the uninformative nature of the auditory component (not simply its absence) is the critical factor, a prediction we tested in a second experiment in which visual speech was paired with auditory white noise. As predicted, visual speech with auditory noise showed enhanced visual cortex responses relative to AV speech. An examination of the anatomical locus of the effects showed that all visual areas, including primary visual cortex, showed enhanced responses. Visual cortex responses to speech are enhanced under circumstances when visual information is most important for comprehension.
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Affiliation(s)
- Inga M Schepers
- Department of Neurobiology and Anatomy, University of Texas Medical School at Houston, Houston, TX, USA Current Address: Department of Psychology, Oldenburg University, Oldenburg, Germany
| | - Daniel Yoshor
- Department of Neurosurgery, Baylor College of Medicine, Houston, TX, USA
| | - Michael S Beauchamp
- Department of Neurobiology and Anatomy, University of Texas Medical School at Houston, Houston, TX, USA
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244
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Lyness RC, Alvarez I, Sereno MI, MacSweeney M. Microstructural differences in the thalamus and thalamic radiations in the congenitally deaf. Neuroimage 2014; 100:347-57. [PMID: 24907483 PMCID: PMC4148523 DOI: 10.1016/j.neuroimage.2014.05.077] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 05/18/2014] [Accepted: 05/28/2014] [Indexed: 12/01/2022] Open
Abstract
There is evidence of both crossmodal and intermodal plasticity in the deaf brain. Here, we investigated whether sub-cortical plasticity, specifically of the thalamus, contributed to this reorganisation. We contrasted diffusion weighted magnetic resonance imaging data from 13 congenitally deaf and 13 hearing participants, all of whom had learnt British Sign Language after 10 years of age. Connectivity based segmentation of the thalamus revealed changes to mean and radial diffusivity in occipital and frontal regions, which may be linked to enhanced peripheral visual acuity, and differences in how visual attention is deployed in the deaf group. Using probabilistic tractography, tracts were traced between the thalamus and its cortical targets, and microstructural measurements were extracted from these tracts. Group differences were found in microstructural measurements of occipital, frontal, somatosensory, motor and parietal thalamo-cortical tracts. Our findings suggest that there is sub-cortical plasticity in the deaf brain, and that white matter alterations can be found throughout the deaf brain, rather than being restricted to, or focussed in the auditory cortex.
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Affiliation(s)
- Rebecca C Lyness
- Cognitive and Perceptual Brain Sciences, 26 Bedford Way, University College London, London WC1H 0AP, UK.
| | - I Alvarez
- Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Martin I Sereno
- Cognitive and Perceptual Brain Sciences, 26 Bedford Way, University College London, London WC1H 0AP, UK; Birkbeck, University of London, Malet Street, Bloomsbury, London WC1E 7HX, UK
| | - Mairéad MacSweeney
- Deafness, Cognition & Language Research Centre, 49 Gordon Square, University College London, London WC1H 0PD, UK; Institute of Cognitive Neuroscience, 17 Queen Square, University College London, London WC1H 3AR, UK
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245
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Ortuño T, Grieve KL, Cao R, Cudeiro J, Rivadulla C. Bursting thalamic responses in awake monkey contribute to visual detection and are modulated by corticofugal feedback. Front Behav Neurosci 2014; 8:198. [PMID: 24910601 PMCID: PMC4039069 DOI: 10.3389/fnbeh.2014.00198] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 05/16/2014] [Indexed: 11/26/2022] Open
Abstract
The lateral geniculate nucleus is the gateway for visual information en route to the visual cortex. Neural activity is characterized by the existence of two firing modes: burst and tonic. Originally associated with sleep, bursts have now been postulated to be a part of the normal visual response, structured to increase the probability of cortical activation, able to act as a "wake-up" call to the cortex. We investigated a potential role for burst in the detection of novel stimuli by recording neuronal activity in the lateral geniculate nucleus (LGN) of behaving monkeys during a visual detection task. Our results show that bursts are often the neuron's first response, and are more numerous in the response to attended target stimuli than to unattended distractor stimuli. Bursts are indicators of the task novelty, as repetition decreased bursting. Because the primary visual cortex is the major modulatory input to the LGN, we compared the results obtained in control conditions with those observed when cortical activity was reduced by TMS. This cortical deactivation reduced visual response related bursting by 90%. These results highlight a novel role for the thalamus, able to code higher order image attributes as important as novelty early in the thalamo-cortical conversation.
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Affiliation(s)
- Tania Ortuño
- Neuroscience and Motor Control Group, NEUROcom, Department of Medicine, University of A CoruñaCoruña, Spain
- Biomedical Research Institute of A Coruna (INIBIC)Coruña, Spain
| | | | - Ricardo Cao
- MODES Group, Department of Mathematics, Faculty of Computer Science, University of A CoruñaCoruña, Spain
| | - Javier Cudeiro
- Neuroscience and Motor Control Group, NEUROcom, Department of Medicine, University of A CoruñaCoruña, Spain
- Biomedical Research Institute of A Coruna (INIBIC)Coruña, Spain
| | - Casto Rivadulla
- Neuroscience and Motor Control Group, NEUROcom, Department of Medicine, University of A CoruñaCoruña, Spain
- Biomedical Research Institute of A Coruna (INIBIC)Coruña, Spain
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246
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Nan J, Liu J, Zhang D, Yang Y, Yan X, Yin Q, Xiong S, von Deneen KM, Liang F, Gong Q, Qin W, Tian J, Zeng F. Altered intrinsic regional activity and corresponding brain pathways reflect the symptom severity of functional dyspepsia. Neurogastroenterol Motil 2014; 26:660-9. [PMID: 24467632 DOI: 10.1111/nmo.12311] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 01/06/2014] [Indexed: 01/09/2023]
Abstract
BACKGROUND Increasing evidence shows central abnormalities in functional dyspepsia (FD) patients, but whether the symptom severity is directly reflected in altered brain patterns remains unclear. The purpose of this study was to explore how FD affected the resting functional brain patterns for different degrees of symptom severity. METHODS Functional magnetic resonance imaging was carried out in 40 FD patients and 20 healthy controls. The resting-state brain changes in regional homogeneity (ReHo) and seed correlation analysis were investigated in patients relative to controls. To what degree the brain changes reflected the severity of the disease was assessed by a pattern classification technique. KEY RESULTS Altered ReHo values (p < 0.05, FDR corrected) were discovered in multiple brain areas in FD patients, and only the anterior cingulate cortex (ACC) and thalamus exhibited significant correlation with the severity of dyspepsia symptoms. Compared with controls, the neural signal changes of the thalamus were not found in the less severe FD patient group but in the relatively more severe group, while the ACC showed aberrations in both groups. Seed-based correlation analysis revealed ACC- and thalamus-related functional connectivity differences between FD patients and controls at a voxel-wise level, and the altered thalamic circuits provided the best performance in distinguishing FD patients with different levels of symptom severity. CONCLUSIONS & INFERENCES Our results indicated that the functional abnormalities of the ACC and thalamus may occur at different clinical courses in FD. This may help us better understand the progression of FD.
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Affiliation(s)
- J Nan
- School of Life Science and Technology, Xidian University, Xi'an, China
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247
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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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248
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Li K, Patel J, Purushothaman G, Marion RT, Casagrande VA. Retinotopic maps in the pulvinar of bush baby (Otolemur garnettii). J Comp Neurol 2014; 521:3432-50. [PMID: 23640865 DOI: 10.1002/cne.23358] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 04/19/2013] [Accepted: 04/25/2013] [Indexed: 11/10/2022]
Abstract
Despite its anatomical prominence, the function of the primate pulvinar is poorly understood. A few electrophysiological studies in simian primates have investigated the functional organization of pulvinar by examining visuotopic maps. Multiple visuotopic maps have been found for all studied simians, with differences in organization reported between New and Old World simians. Given that prosimians are considered closer to the common ancestors of New and Old World primates, we investigated the visuotopic organization of pulvinar in the prosimian bush baby (Otolemur garnettii). Single-electrode extracellular recording was used to find the retinotopic maps in the lateral (PL) and inferior (PI) pulvinar. Based on recordings across cases, a 3D model of the map was constructed. From sections stained for Nissl bodies, myelin, acetylcholinesterase, calbindin, or cytochrome oxidase, we identified three PI chemoarchitectonic subdivisions, lateral central (PIcl), medial central (PIcm), and medial (PIm) inferior pulvinar. Two major retinotopic maps were identified that cover PL and PIcl, the dorsal one in dorsal PL and the ventral one in PIcl and ventral PL. Both maps represent central vision at the posterior end of the border between the maps, the upper visual field in the lateral half and the lower visual field in the medial half. They share many features with the maps reported for the pulvinar of simians, including the location in pulvinar and the representation of the upper-lower and central-peripheral visual field axes. The second-order representation in the lateral map and a laminar organization are likely features specific to Old World simians.
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Affiliation(s)
- K Li
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, 37240
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249
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Abstract
Metabotropic glutamate receptors (mGluRs) are found throughout thalamus and cortex and are clearly important to circuit behavior in both structures, and so considering only participation of ionotropic glutamate receptors (e.g., [R,S]-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid [AMPA] and N-methyl-d-aspartate receptors [NMDA] receptors) in glutamatergic processing would be an unfortunate oversimplification. These mGluRs are found both postsynaptically, on target cells of glutamatergic afferents, and presynaptically, on various synaptic terminals themselves, and when activated, they produce prolonged effects lasting at least hundreds of msec to several sec and perhaps longer. Two main types exist: activation of group I mGluRs causes postsynaptic depolarization, and group II, hyperpolarization. Both types are implicated in synaptic plasticity, both short term and long term. Their evident importance in functioning of thalamus and cortex makes it critical to develop a better understanding of how these receptors are normally activated, especially because they also seem implicated in a wide range of neurological and cognitive pathologies.
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250
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Long Z, Jiang YM, Li XR, Fadel W, Xu J, Yeh CL, Long LL, Luo HL, Harezlak J, Murdoch JB, Zheng W, Dydak U. Vulnerability of welders to manganese exposure--a neuroimaging study. Neurotoxicology 2014; 45:285-92. [PMID: 24680838 DOI: 10.1016/j.neuro.2014.03.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Revised: 03/01/2014] [Accepted: 03/19/2014] [Indexed: 01/19/2023]
Abstract
Increased manganese (Mn) exposure is known to cause cognitive, psychiatric and motor deficits. Mn exposure occurs in different occupational settings, where the airborne Mn level and the size of respirable particulates may vary considerably. Recently the importance of the role of the cerebral cortex in Mn toxicity has been highlighted, especially in Mn-induced neuropsychological effects. In this study we used magnetic resonance imaging (MRI) to evaluate brain Mn accumulation using T1 signal intensity indices and to examine changes in brain iron content using T2* contrast, as well as magnetic resonance spectroscopy (MRS) to measure exposure-induced metabolite changes non-invasively in cortical and deep brain regions in Mn-exposed welders, Mn-exposed smelter workers and control factory workers with no measurable exposure to Mn. MRS data as well as T1 signal intensity indices and T2* values were acquired from the frontal cortex, posterior cingulate cortex, hippocampus, and thalamus. Smelters were exposed to higher air Mn levels and had a longer duration of exposure, which was reflected in higher Mn levels in erythrocytes and urine than in welders. Nonetheless, welders had more significant metabolic differences compared to controls than did the smelter workers, especially in the frontal cortex. T1 hyperintensities in the globus pallidus were observed in both Mn-exposed groups, but only welders showed significantly higher thalamic and hippocampal T1 hyperintensities, as well as significantly reduced T2* values in the frontal cortex. Our results indicate that (1) the cerebral cortex, in particular the frontal cortex, is clearly involved in Mn neurotoxic effects and (2) in spite of the lower air Mn levels and shorter duration of exposure, welders exhibit more extensive neuroimaging changes compared to controls than smelters, including measurable deposition of Mn in more brain areas. These results indicate that the type of exposure (particulate sizes, dust versus fume) and route of exposure play an important role in the extent of Mn-induced toxic effects on the brain.
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Affiliation(s)
- Zaiyang Long
- School of Health Sciences, Purdue University, West Lafayette, IN, USA; Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Yue-Ming Jiang
- Department of Health Toxicology, Guangxi Medical University, Nanning, China.
| | - Xiang-Rong Li
- Department of Radiology, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - William Fadel
- Department of Biostatistics, Richard M. Fairbanks School of Public Health, Indiana University, Indianapolis, IN, USA
| | - Jun Xu
- School of Health Sciences, Purdue University, West Lafayette, IN, USA; Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Chien-Lin Yeh
- School of Health Sciences, Purdue University, West Lafayette, IN, USA; Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Li-Ling Long
- Department of Radiology, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Hai-Lan Luo
- Department of Health Toxicology, Guangxi Medical University, Nanning, China
| | - Jaroslaw Harezlak
- Department of Biostatistics, Richard M. Fairbanks School of Public Health, Indiana University, Indianapolis, IN, USA; Department of Biostatistics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - James B Murdoch
- Toshiba Medical Research Institute USA, Mayfield Village, OH, USA
| | - Wei Zheng
- School of Health Sciences, Purdue University, West Lafayette, IN, USA
| | - Ulrike Dydak
- School of Health Sciences, Purdue University, West Lafayette, IN, USA; Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, USA.
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