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Homologous organization of cerebellar pathways to sensory, motor, and associative forebrain. Cell Rep 2021; 36:109721. [PMID: 34551311 PMCID: PMC8506234 DOI: 10.1016/j.celrep.2021.109721] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 06/06/2021] [Accepted: 08/25/2021] [Indexed: 12/31/2022] Open
Abstract
Cerebellar outputs take polysynaptic routes to reach the rest of the brain, impeding conventional tracing. Here, we quantify pathways between the cerebellum and forebrain by using transsynaptic tracing viruses and a whole-brain analysis pipeline. With retrograde tracing, we find that most descending paths originate from the somatomotor cortex. Anterograde tracing of ascending paths encompasses most thalamic nuclei, especially ventral posteromedial, lateral posterior, mediodorsal, and reticular nuclei. In the neocortex, sensorimotor regions contain the most labeled neurons, but we find higher densities in associative areas, including orbital, anterior cingulate, prelimbic, and infralimbic cortex. Patterns of ascending expression correlate with c-Fos expression after optogenetic inhibition of Purkinje cells. Our results reveal homologous networks linking single areas of the cerebellar cortex to diverse forebrain targets. We conclude that shared areas of the cerebellum are positioned to provide sensory-motor information to regions implicated in both movement and nonmotor function. Pisano et al. use transsynaptic tracing and whole-brain light-sheet microscopy to quantitatively map cerebellar paths to and from the forebrain, including relatively dense projections to the prefrontal neocortex. Divergence of paths from single injection sites suggests that a single cerebellar region can influence multiple thalamic and neocortical targets at once.
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Cassel JC, Pereira de Vasconcelos A. Routes of the thalamus through the history of neuroanatomy. Neurosci Biobehav Rev 2021; 125:442-465. [PMID: 33676963 DOI: 10.1016/j.neubiorev.2021.03.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 02/19/2021] [Accepted: 03/01/2021] [Indexed: 12/24/2022]
Abstract
The most distant roots of neuroanatomy trace back to antiquity, with the first human dissections, but no document which would identify the thalamus as a brain structure has reached us. Claudius Galenus (Galen) gave to the thalamus the name 'thalamus nervorum opticorum', but later on, other names were used (e.g., anchae, or buttocks-like). In 1543, Andreas Vesalius provided the first quality illustrations of the thalamus. During the 19th century, tissue staining techniques and ablative studies contributed to the breakdown of the thalamus into subregions and nuclei. The next step was taken using radiomarkers to identify connections in the absence of lesions. Anterograde and retrograde tracing methods arose in the late 1960s, supporting extension, revision, or confirmation of previously established knowledge. The use of the first viral tracers introduced a new methodological breakthrough in the mid-1970s. Another important step was supported by advances in neuroimaging of the thalamus in the 21th century. The current review follows the history of the thalamus through these technical revolutions from Antiquity to the present day.
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Affiliation(s)
- Jean-Christophe Cassel
- Laboratoire de Neurosciences Cognitives et Adaptatives, Université de Strasbourg, F-67000 Strasbourg, France; LNCA, UMR 7364 - CNRS, F-67000 Strasbourg, France.
| | - Anne Pereira de Vasconcelos
- Laboratoire de Neurosciences Cognitives et Adaptatives, Université de Strasbourg, F-67000 Strasbourg, France; LNCA, UMR 7364 - CNRS, F-67000 Strasbourg, France
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Delhaye BP, Long KH, Bensmaia SJ. Neural Basis of Touch and Proprioception in Primate Cortex. Compr Physiol 2018; 8:1575-1602. [PMID: 30215864 PMCID: PMC6330897 DOI: 10.1002/cphy.c170033] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The sense of proprioception allows us to keep track of our limb posture and movements and the sense of touch provides us with information about objects with which we come into contact. In both senses, mechanoreceptors convert the deformation of tissues-skin, muscles, tendons, ligaments, or joints-into neural signals. Tactile and proprioceptive signals are then relayed by the peripheral nerves to the central nervous system, where they are processed to give rise to percepts of objects and of the state of our body. In this review, we first examine briefly the receptors that mediate touch and proprioception, their associated nerve fibers, and pathways they follow to the cerebral cortex. We then provide an overview of the different cortical areas that process tactile and proprioceptive information. Next, we discuss how various features of objects-their shape, motion, and texture, for example-are encoded in the various cortical fields, and the susceptibility of these neural codes to attention and other forms of higher-order modulation. Finally, we summarize recent efforts to restore the senses of touch and proprioception by electrically stimulating somatosensory cortex. © 2018 American Physiological Society. Compr Physiol 8:1575-1602, 2018.
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Affiliation(s)
- Benoit P Delhaye
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, USA
| | - Katie H Long
- Committee on Computational Neuroscience, University of Chicago, Chicago, USA
| | - Sliman J Bensmaia
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, USA.,Committee on Computational Neuroscience, University of Chicago, Chicago, USA
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Anterolateral Motor Cortex Connects with a Medial Subdivision of Ventromedial Thalamus through Cell Type-Specific Circuits, Forming an Excitatory Thalamo-Cortico-Thalamic Loop via Layer 1 Apical Tuft Dendrites of Layer 5B Pyramidal Tract Type Neurons. J Neurosci 2018; 38:8787-8797. [PMID: 30143573 DOI: 10.1523/jneurosci.1333-18.2018] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 08/03/2018] [Accepted: 08/09/2018] [Indexed: 01/18/2023] Open
Abstract
The anterolateral motor cortex (ALM) and ventral medial (VM) thalamus are functionally linked to support persistent activity during motor planning. We analyzed the underlying synaptic interconnections using optogenetics and electrophysiology in mice (female/male). In cortex, thalamocortical (TC) axons from VM thalamus excited VM-projecting pyramidal tract (PT) neurons in layer 5B of ALM. These axons also strongly excited layer 2/3 neurons (which strongly excite PT neurons, as previously shown) but not VM-projecting corticothalamic (CT) neurons in layer 6. The strongest connections in the VM → PT circuit were localized to apical tuft dendrites of PT neurons, in layer 1. These tuft inputs were selectively augmented after blocking hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. In thalamus, axons from ALM PT neurons excited ALM-projecting VM neurons, located medially in VM. These axons provided weak input to neurons in mediodorsal nucleus, and little or no input either to neurons in the GABAergic reticular thalamic nucleus or to neurons in VM projecting to primary motor cortex (M1). Conversely, M1 PT axons excited M1- but not ALM-projecting VM neurons. Our findings indicate, first, a set of cell type-specific connections forming an excitatory thalamo-cortico-thalamic loop for ALM ↔ VM communication and a circuit-level substrate for supporting reverberant activity in this system. Second, a key feature of this loop is the prominent involvement of layer 1 synapses onto apical dendrites, a subcellular compartment with distinct signaling properties, including HCN-mediated gain control. Third, the segregation of the ALM ↔ VM loop from M1-related circuits of VM adds cellular-level support for the concept of parallel pathway organization in the motor system.SIGNIFICANCE STATEMENT Anterolateral motor cortex (ALM), a higher-order motor area in the mouse, and ventromedial (VM) thalamus are anatomically and functionally linked, but their synaptic interconnections at the cellular level are unknown. Our results show that ALM pyramidal tract neurons monosynaptically excite ALM-projecting thalamocortical neurons in a medial subdivision of VM thalamus, and vice versa. The thalamo-cortico-thalamic loop formed by these recurrent connections constitutes a circuit-level substrate for supporting reverberant activity in this system.
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Abstract
Somatosensory areas containing topographic maps of the body surface are a major feature of parietal cortex. In primates, parietal cortex contains four somatosensory areas, each with its own map, with the primary cutaneous map in area 3b. Rodents have at least three parietal somatosensory areas. Maps are not isomorphic to the body surface, but magnify behaviorally important skin regions, which include the hands and face in primates, and the whiskers in rodents. Within each map, intracortical circuits process tactile information, mediate spatial integration, and support active sensation. Maps may also contain fine-scale representations of touch submodalities, or direction of tactile motion. Functional representations are more overlapping than suggested by textbook depictions of map topography. The whisker map in rodent somatosensory cortex is a canonic system for studying cortical microcircuits, sensory coding, and map plasticity. Somatosensory maps are plastic throughout life in response to altered use or injury. This chapter reviews basic principles and recent findings in primate, human, and rodent somatosensory maps.
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Affiliation(s)
- Samuel Harding-Forrester
- Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, CA, United States
| | - Daniel E Feldman
- Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, CA, United States.
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An Ultrastructural Study of the Thalamic Input to Layer 4 of Primary Motor and Primary Somatosensory Cortex in the Mouse. J Neurosci 2017; 37:2435-2448. [PMID: 28137974 DOI: 10.1523/jneurosci.2557-16.2017] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 01/17/2017] [Accepted: 01/19/2017] [Indexed: 12/22/2022] Open
Abstract
The traditional classification of primary motor cortex (M1) as an agranular area has been challenged recently when a functional layer 4 (L4) was reported in M1. L4 is the principal target for thalamic input in sensory areas, which raises the question of how thalamocortical synapses formed in M1 in the mouse compare with those in neighboring sensory cortex (S1). We identified thalamic boutons by their immunoreactivity for the vesicular glutamate transporter 2 (VGluT2) and performed unbiased disector counts from electron micrographs. We discovered that the thalamus contributed proportionately only half as many synapses to the local circuitry of L4 in M1 compared with S1. Furthermore, thalamic boutons in M1 targeted spiny dendrites exclusively, whereas ∼9% of synapses were formed with dendrites of smooth neurons in S1. VGluT2+ boutons in M1 were smaller and formed fewer synapses per bouton on average (1.3 vs 2.1) than those in S1, but VGluT2+ synapses in M1 were larger than in S1 (median postsynaptic density areas of 0.064 μm2 vs 0.042 μm2). In M1 and S1, thalamic synapses formed only a small fraction (12.1% and 17.2%, respectively) of all of the asymmetric synapses in L4. The functional role of the thalamic input to L4 in M1 has largely been neglected, but our data suggest that, as in S1, the thalamic input is amplified by the recurrent excitatory connections of the L4 circuits. The lack of direct thalamic input to inhibitory neurons in M1 may indicate temporal differences in the inhibitory gating in L4 of M1 versus S1.SIGNIFICANCE STATEMENT Classical interpretations of the function of primary motor cortex (M1) emphasize its lack of the granular layer 4 (L4) typical of sensory cortices. However, we show here that, like sensory cortex (S1), mouse M1 also has the canonical circuit motif of a core thalamic input to the middle cortical layer and that thalamocortical synapses form a small fraction (M1: 12%; S1: 17%) of all asymmetric synapses in L4 of both areas. Amplification of thalamic input by recurrent local circuits is thus likely to be a significant mechanism in both areas. Unlike M1, where thalamocortical boutons typically form a single synapse, thalamocortical boutons in S1 usually formed multiple synapses, which means they can be identified with high probability in the electron microscope without specific labeling.
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Liao CC, Reed JL, Kaas JH, Qi HX. Intracortical connections are altered after long-standing deprivation of dorsal column inputs in the hand region of area 3b in squirrel monkeys. J Comp Neurol 2015; 524:1494-526. [PMID: 26519356 DOI: 10.1002/cne.23921] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 10/01/2015] [Accepted: 10/26/2015] [Indexed: 11/09/2022]
Abstract
A complete unilateral lesion of the dorsal column somatosensory pathway in the upper cervical spinal cord deactivates neurons in the hand region in contralateral somatosensory cortex (areas 3b and 1). Over weeks to months of recovery, parts of the hand region become reactivated by touch on the hand or face. To determine whether changes in cortical connections potentially contribute to this reactivation, we injected tracers into electrophysiologically identified locations in cortex of area 3b representing the reactivated hand and normally activated face in adult squirrel monkeys. Our results indicated that even when only partially reactivated, most of the expected connections of area 3b remained intact. These intact connections include the majority of intrinsic connections within area 3b; feedback connections from area 1, secondary somatosensory cortex (S2), parietal ventral area (PV), and other cortical areas; and thalamic inputs from the ventroposterior lateral nucleus (VPL). In addition, tracer injections in the reactivated hand region of area 3b labeled more neurons in the face and shoulder regions of area 3b than in normal monkeys, and injections in the face region of area 3b labeled more neurons in the hand region. Unexpectedly, the intrinsic connections within area 3b hand cortex were more widespread after incomplete dorsal column lesions (DCLs) than after a complete DCL. Although these additional connections were limited, these changes in connections may contribute to the reactivation process after injuries. J. Comp. Neurol. 524:1494-1526, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Chia-Chi Liao
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, 37240
| | - Jamie L Reed
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, 37240
| | - Jon H Kaas
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, 37240
| | - Hui-Xin Qi
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, 37240
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Yamawaki N, Borges K, Suter BA, Harris KD, Shepherd GMG. A genuine layer 4 in motor cortex with prototypical synaptic circuit connectivity. eLife 2014; 3:e05422. [PMID: 25525751 PMCID: PMC4290446 DOI: 10.7554/elife.05422] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 12/18/2014] [Indexed: 12/28/2022] Open
Abstract
The motor cortex (M1) is classically considered an agranular area, lacking a distinct layer 4 (L4). Here, we tested the idea that M1, despite lacking a cytoarchitecturally visible L4, nevertheless possesses its equivalent in the form of excitatory neurons with input–output circuits like those of the L4 neurons in sensory areas. Consistent with this idea, we found that neurons located in a thin laminar zone at the L3/5A border in the forelimb area of mouse M1 have multiple L4-like synaptic connections: excitatory input from thalamus, largely unidirectional excitatory outputs to L2/3 pyramidal neurons, and relatively weak long-range corticocortical inputs and outputs. M1-L4 neurons were electrophysiologically diverse but morphologically uniform, with pyramidal-type dendritic arbors and locally ramifying axons, including branches extending into L2/3. Our findings therefore identify pyramidal neurons in M1 with the expected prototypical circuit properties of excitatory L4 neurons, and question the traditional assumption that motor cortex lacks this layer. DOI:http://dx.doi.org/10.7554/eLife.05422.001 In 1909, a German scientist called Korbinian Brodmann published the first map of the outer layer of the human brain. After staining neurons with a dye and studying the structures of the cells and how they were organized, he realized that he could divide the cortex into 43 numbered regions. Most Brodmann areas can be divided into a number of horizontal layers, with layer 1 being closest to the surface of the brain. Neurons in the different layers form distinct sets of connections, and the relative thickness of the layers has implications for the function carried out by that area. It is thought, for example, that the motor cortex does not have a layer 4, which suggests that the neural circuitry that controls movement differs from that in charge of vision, hearing, and other functions. Yamawaki et al. now challenge this view by providing multiple lines of evidence for the existence of layer 4 in the motor cortex in mice. Neurons at the border between layer 3 and layer 5A in the motor cortex possess many of the same properties as the neurons in layer 4 in sensory cortex. In particular, they receive inputs from a brain region called the thalamus, and send outputs to neurons in layers 2 and 3. Yamawaki et al. go on to characterize some of the properties of the neurons in the putative layer 4 of the motor cortex, finding that they do not look like the specialized ‘stellate’ cells that are found in some other areas of the cortex. Instead, they resemble the ‘pyramidal’ type of neuron that is found in all layers and areas of the cortex. The discovery that the motor cortex is more similar in its circuit connections to other area of the cortex than previously thought has important implications for our understanding of this region of the brain. DOI:http://dx.doi.org/10.7554/eLife.05422.002
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Affiliation(s)
- Naoki Yamawaki
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Katharine Borges
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Benjamin A Suter
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Kenneth D Harris
- Institute of Neurology, University College London, London, United Kingdom
| | - Gordon M G Shepherd
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, United States
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Ashaber M, Pálfi E, Friedman RM, Palmer C, Jákli B, Chen LM, Kántor O, Roe AW, Négyessy L. Connectivity of somatosensory cortical area 1 forms an anatomical substrate for the emergence of multifinger receptive fields and complex feature selectivity in the squirrel monkey (Saimiri sciureus). J Comp Neurol 2014; 522:1769-85. [PMID: 24214200 DOI: 10.1002/cne.23499] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 10/15/2013] [Accepted: 10/15/2013] [Indexed: 11/08/2022]
Abstract
Converging evidence shows that interaction of digit-specific input, which is required to form global tactile percepts, begins as early as area 3b in the primary somatosensory cortex with the involvement of intrinsic lateral connections. How tactile processing is further elaborated in area 1, the next stage of the somatosensory cortical hierarchy, is less understood. This question was investigated by studying the tangential distribution of intrinsic and interareal connections of finger representations of area 1. Retrogradely labeled cell densities and anterogradely labeled fibers and terminal patches were plotted and quantified with respect to the hand representation by combining tract tracing with electrophysiological mapping and intrinsic signal optical imaging in somatosensory areas. Intrinsic connections of distal finger pad representations of area 1 spanned the representation of multiple digits indicating strong cross-digit connectivity. Area 1 distal finger pad regions also established high-density connections with homotopic regions of areas 3b and 2. Although similar to area 3b, connections of area 1 distributed more widely and covered a larger somatotopic representation including more proximal parts of the finger representations. The lateral connectivity pattern of area 1 is a suitable anatomical substrate of the emergence of multifinger receptive fields, complex feature selectivity, and invariant stimulus properties of the neurons.
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Affiliation(s)
- Mária Ashaber
- Complex Systems and Computational Neuroscience Group, Wigner Research Center for Physics, Hungarian Academy of Sciences, Budapest, H-1121, Hungary; Department of Anatomy, Histology, and Embryology, Semmelweis University Medical School, Budapest, H-1094, Hungary
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Liao CC, Gharbawie OA, Qi H, Kaas JH. Cortical connections to single digit representations in area 3b of somatosensory cortex in squirrel monkeys and prosimian galagos. J Comp Neurol 2014; 521:3768-90. [PMID: 23749740 DOI: 10.1002/cne.23377] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 04/30/2013] [Accepted: 05/23/2013] [Indexed: 11/06/2022]
Abstract
The ventral posterior nucleus of thalamus sends highly segregated inputs into each digit representation in area 3b of primary somatosensory cortex. However, the spatial organization of the connections that link digit representations of areas 3b with other somatosensory areas is less understood. Here we examined the cortical inputs to individual digit representations of area 3b in four squirrel monkeys and one prosimian galago. Retrograde tracers were injected into neurophysiologically defined representations of individual digits of area 3b. Cortical tissues were cut parallel to the surface in some cases and showed that feedback projections to individual digits overlapped extensively in the hand representations of areas 3b, 1, and parietal ventral (PV) and second somatosensory (S2) areas. Other regions with overlapping populations of labeled cells included area 3a and primary motor cortex (M1). The results were confirmed in other cases in which the cortical tissues were cut in the coronal plane. The same cases also showed that cells were primarily labeled in the infragranular and supragranular layers. Thus, feedback projections to individual digit representations in area 3b mainly originate from multiple digits and other portions of hand representations of areas 3b, 1, PV, and S2. This organization is in stark contrast to the segregated thalamocortical inputs, which originate in single digit representations and terminate in the matching digit representation in the cortex. The organization of feedback connections could provide a substrate for the integration of information across the representations of adjacent digits in area 3b.
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Affiliation(s)
- Chia-Chi Liao
- Department of Psychology, Vanderbilt University, Nashville, Tennessee
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García-Cabezas MÁ, Barbas H. Area 4 has layer IV in adult primates. Eur J Neurosci 2014; 39:1824-34. [PMID: 24735460 PMCID: PMC4201116 DOI: 10.1111/ejn.12585] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 02/07/2014] [Accepted: 03/07/2014] [Indexed: 11/27/2022]
Abstract
There are opposing views about the status of layer IV in the primary motor cortex (area 4). Cajal described a layer IV in area 4 of adult humans. In contrast, Brodmann found layer IV in developmental but not in adult primates and called area 4 'agranular'. We addressed this issue in rhesus monkeys using the neural marker SMI-32, which labels neurons in lower layer III and upper layer V, but not in layer IV. SMI-32 delineated a central unlabeled cortical stripe in area 4 that corresponds to layer IV, which was populated with small interneurons also found in layer IV in 'granular' areas (such as area 46). We distinguished layer IV interneurons from projection neurons in the layers above and below using cellular criteria. The commonly used term 'agranular' for area 4 is also used for the phylogenetically ancient limbic cortices, confusing areas that differ markedly in laminar structure. This issue pertains to the systematic variation in the architecture across cortices, traced from limbic cortices through areas with increasingly more elaborate laminar structure. The principle of systematic variation can be used to predict laminar patterns of connections across cortical systems. This principle places area 4 and agranular anterior cingulate cortices at opposite poles of the graded laminar differentiation of motor cortices. The status of layer IV in area 4 thus pertains to core organisational features of the cortex, its connections and evolution.
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Affiliation(s)
| | - Helen Barbas
- Neural Systems Laboratory (www.bu.edu/neural), Dept. of Health Sciences, Boston University, Boston, MA, USA
- Graduate Program in Neuroscience, Boston University and School of Medicine, Boston, MA, USA
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Alfano C, Magrinelli E, Harb K, Studer M. The nuclear receptors COUP-TF: a long-lasting experience in forebrain assembly. Cell Mol Life Sci 2014; 71:43-62. [PMID: 23525662 PMCID: PMC11114017 DOI: 10.1007/s00018-013-1320-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Revised: 02/14/2013] [Accepted: 03/04/2013] [Indexed: 12/16/2022]
Abstract
Chicken ovalbumin upstream promoter transcription factors (COUP-TFs) are nuclear receptors belonging to the superfamily of the steroid/thyroid hormone receptors. Members of this family are internalized to the nucleus both in a ligand-dependent or -independent manner and act as strong transcriptional regulators by binding to the DNA of their target genes. COUP-TFs are defined as orphan receptors, since ligands regulating their activity have not so far been identified. From the very beginning of metazoan evolution, these molecules have been involved in various key events during embryonic development and organogenesis. In this review, we will mainly focus on their function during development and maturation of the central nervous system, which has been well characterized in various animal classes ranging from ctenophores to mammals. We will start by introducing the current knowledge on COUP-TF mechanisms of action and then focus our discussion on the crucial processes underlying forebrain ontogenesis, with special emphasis on mammalian development. Finally, the conserved roles of COUP-TFs along phylogenesis will be highlighted, and some hypotheses, worth exploring in future years to gain more insight into the mechanisms controlled by these factors, will be proposed.
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Affiliation(s)
- Christian Alfano
- Institute of Biology Valrose, iBV, UMR INSERM1091/CNRS7277/UNS, 06108 Nice, France
- University of Nice-Sophia Antipolis, UFR Sciences, 06108 Nice, France
| | - Elia Magrinelli
- Institute of Biology Valrose, iBV, UMR INSERM1091/CNRS7277/UNS, 06108 Nice, France
- University of Nice-Sophia Antipolis, UFR Sciences, 06108 Nice, France
| | - Kawssar Harb
- Institute of Biology Valrose, iBV, UMR INSERM1091/CNRS7277/UNS, 06108 Nice, France
- University of Nice-Sophia Antipolis, UFR Sciences, 06108 Nice, France
| | - Michèle Studer
- Institute of Biology Valrose, iBV, UMR INSERM1091/CNRS7277/UNS, 06108 Nice, France
- University of Nice-Sophia Antipolis, UFR Sciences, 06108 Nice, France
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Hsu WY, Kwan SY, Liao KK, Chen RS, Lin YY. Altered inhibitory modulation of somatosensory cortices in paroxysmal kinesigenic dyskinesia. Mov Disord 2013; 28:1728-31. [DOI: 10.1002/mds.25656] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 07/11/2013] [Accepted: 07/29/2013] [Indexed: 11/09/2022] Open
Affiliation(s)
- Wan-Yu Hsu
- Institute of Brain Science; National Yang-Ming University; Taipei Taiwan
- Laboratory of Neurophysiology; Taipei Veterans General Hospital; Taipei Taiwan
- Integrated Brain Research Laboratory; Taipei Veterans General Hospital; Taipei Taiwan
| | - Shang-Yeong Kwan
- Department of Neurology; National Yang-Ming University; Taipei Taiwan
- Department of Neurology; Taipei Veterans General Hospital; Taipei Taiwan
| | - Kwong-Kum Liao
- Department of Neurology; National Yang-Ming University; Taipei Taiwan
- Department of Neurology; Taipei Veterans General Hospital; Taipei Taiwan
| | - Rou-Shayn Chen
- Department of Neurology; Chang Gung Memorial Hospital and Chang Gung University College of Medicine; Taipei Taiwan
| | - Yung-Yang Lin
- Institute of Brain Science; National Yang-Ming University; Taipei Taiwan
- Laboratory of Neurophysiology; Taipei Veterans General Hospital; Taipei Taiwan
- Integrated Brain Research Laboratory; Taipei Veterans General Hospital; Taipei Taiwan
- Department of Neurology; National Yang-Ming University; Taipei Taiwan
- Department of Neurology; Taipei Veterans General Hospital; Taipei Taiwan. Institute of Physiology; National Yang-Ming University; Taipei Taiwan. Institute of Clinical Medicine; National Yang-Ming University; Taipei Taiwan
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14
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Brock AA, Friedman RM, Fan RH, Roe AW. Optical imaging of cortical networks via intracortical microstimulation. J Neurophysiol 2013; 110:2670-8. [PMID: 24027103 DOI: 10.1152/jn.00879.2012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Understanding cortical organization is key to understanding brain function. Distinct neural networks underlie the functional organization of the cerebral cortex; however, little is known about how different nodes in the cortical network interact during perceptual processing and motor behavior. To study cortical network function we examined whether the optical imaging of intrinsic signals (OIS) reveals the functional patterns of activity evoked by electrical cortical microstimulation. We examined the effects of current amplitude, train duration, and depth of cortical stimulation on the hemodynamic response to electrical microstimulation (250-Hz train, 0.4-ms pulse duration) in anesthetized New World monkey somatosensory cortex. Electrical stimulation elicited a restricted cortical response that varied according to stimulation parameters and electrode depth. Higher currents of stimulation recruited more areas of cortex than smaller currents. The largest cortical responses were seen when stimulation was delivered around cortical layer 4. Distinct local patches of activation, highly suggestive of local projections, around the site of stimulation were observed at different depths of stimulation. Thus we find that specific electrical stimulation parameters can elicit activation of single cortical columns and their associated columnar networks, reminiscent of anatomically labeled networks. This novel functional tract tracing method will open new avenues for investigating relationships of local cortical organization.
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Affiliation(s)
- Andrea A Brock
- Department of Psychology, Vanderbilt University, Nashville, Tennessee
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Alfano C, Studer M. Neocortical arealization: evolution, mechanisms, and open questions. Dev Neurobiol 2013; 73:411-47. [PMID: 23239642 DOI: 10.1002/dneu.22067] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 11/03/2012] [Accepted: 12/06/2012] [Indexed: 12/13/2022]
Abstract
The mammalian neocortex is a structure with no equals in the vertebrates and is the seat of the highest cerebral functions, such as thoughts and consciousness. It is radially organized into six layers and tangentially subdivided into functional areas deputed to the elaboration of sensory information, association between different stimuli, and selection and triggering of voluntary movements. The process subdividing the neocortical field into several functional areas is called "arealization". Each area has its own cytoarchitecture, connectivity, and peculiar functions. In the last century, several neuroscientists have investigated areal structure and the mechanisms that have led during evolution to the rising of the neocortex and its organization. The extreme conservation in the positioning and wiring of neocortical areas among different mammalian families suggests a conserved genetic program orchestrating neocortical patterning. However, the impressive plasticity of the neocortex, which is able to rewire and reorganize areal structures and connectivity after impairments of sensory pathways, argues for a more complex scenario. Indeed, even if genetics and molecular biology helped in identifying several genes involved in the arealization process, the logic underlying the neocortical bauplan is still beyond our comprehension. In this review, we will introduce the present knowledge and hypotheses on the ontogenesis and evolution of neocortical areas. Then, we will focus our attention on some open issues, which are still unresolved, and discuss some recent studies that might open new directions to be explored in the next few years.
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Affiliation(s)
- Christian Alfano
- Institute of Biology Valrose, iBV, UMR INSERM1091/CNRS7277/UNS, Nice, F-06108, France.
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Hajnik T, Tóth A, Détári L. Characteristic changes in the slow cortical waves after a 6-h sleep deprivation in rat. Brain Res 2013; 1501:1-11. [PMID: 23333371 DOI: 10.1016/j.brainres.2012.12.047] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 12/14/2012] [Accepted: 12/24/2012] [Indexed: 10/27/2022]
Abstract
Sleep deprivation is followed by an increase in EEG delta power during recovery sleep indicating an increased sleep propensity. Delta waves mostly reflect the rhythmic recurring of generalized hyperpolarizations (DOWN state) in cortical neurons causing large, deep-positive waves in the LFP. Enhancement of delta power in recovery sleep can be the consequence of either the more frequent occurrence, or the higher amplitude caused by higher synchrony, or the longer duration of these DOWN states. In the present experiments, we examined these possibilities and found the strongest increase in the incidence of slow deep positive LFP waves (slow waves) following sleep deprivation indicating enhancement of DOWN state inducing and/or weakening of UP state maintaining processes. The strong decrease in multiunit activity during slow waves was preceded by a gradual buildup of activity. The significant correlation between these changes both in control and recovery recordings indicate that excitation might determine the subsequent drop in activity. Increased sensitivity of cortical neurons to excitation might offer an explanation for this observation. Current-source-density analysis indicated in our experiments that the first sources during DOWN states appeared in layer III-IV. Activation was then displaced to layer V. In the motor cortex, both corticocortical and thalamocortical fibers terminate in layer III that provides a strong feedforward excitation to layer V. As propagation of facilitatory signals through cortical layers is downwardly biased, disfacilitation might also follow this pattern. Sleep deprivation caused only quantitative differences in the sink-source patterns, indicating that existing processes were enhanced by sleep deprivation.
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Affiliation(s)
- Tünde Hajnik
- Department of Physiology and Neurobiology, Eötvös Loránd University, Budapest, Hungary.
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Goodbye to Edward G. (Ted) Jones, MD, DPhil, 1939-2011. J Comp Neurol 2011; 519:3125-7. [DOI: 10.1002/cne.22749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Li N, Downey JE, Bar-Shir A, Gilad AA, Walczak P, Kim H, Joel SE, Pekar JJ, Thakor NV, Pelled G. Optogenetic-guided cortical plasticity after nerve injury. Proc Natl Acad Sci U S A 2011; 108:8838-43. [PMID: 21555573 PMCID: PMC3102379 DOI: 10.1073/pnas.1100815108] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Peripheral nerve injury causes sensory dysfunctions that are thought to be attributable to changes in neuronal activity occurring in somatosensory cortices both contralateral and ipsilateral to the injury. Recent studies suggest that distorted functional response observed in deprived primary somatosensory cortex (S1) may be the result of an increase in inhibitory interneuron activity and is mediated by the transcallosal pathway. The goal of this study was to develop a strategy to manipulate and control the transcallosal activity to facilitate appropriate plasticity by guiding the cortical reorganization in a rat model of sensory deprivation. Since transcallosal fibers originate mainly from excitatory pyramidal neurons somata situated in laminae III and V, the excitatory neurons in rat S1 were engineered to express halorhodopsin, a light-sensitive chloride pump that triggers neuronal hyperpolarization. Results from electrophysiology, optical imaging, and functional MRI measurements are concordant with that within the deprived S1, activity in response to intact forepaw electrical stimulation was significantly increased by concurrent illumination of halorhodopsin over the healthy S1. Optogenetic manipulations effectively decreased the adverse inhibition of deprived cortex and revealed the major contribution of the transcallosal projections, showing interhemispheric neuroplasticity and thus, setting a foundation to develop improved rehabilitation strategies to restore cortical functions.
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Affiliation(s)
- Nan Li
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD 21205
- Department of Biomedical Engineering and
| | - John E. Downey
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD 21205
| | - Amnon Bar-Shir
- Cellular Imaging Section, Vascular Biology Program, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205; and
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287
| | - Assaf A. Gilad
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD 21205
- Cellular Imaging Section, Vascular Biology Program, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205; and
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287
| | - Piotr Walczak
- Cellular Imaging Section, Vascular Biology Program, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205; and
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287
| | - Heechul Kim
- Cellular Imaging Section, Vascular Biology Program, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205; and
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287
| | - Suresh E. Joel
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD 21205
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287
| | - James J. Pekar
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD 21205
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287
| | | | - Galit Pelled
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD 21205
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287
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Jones EG. Organization of the Thalamocortical Complex and its Relation to Sensory Processes. Compr Physiol 2011. [DOI: 10.1002/cphy.cp010305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kern A, Siebert U, Cozzi B, Hof P, Oelschläger H. Stereology of the Neocortex in Odontocetes: Qualitative, Quantitative, and Functional Implications. BRAIN, BEHAVIOR AND EVOLUTION 2011; 77:79-90. [DOI: 10.1159/000323674] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2010] [Accepted: 12/13/2010] [Indexed: 11/19/2022]
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Abstract
AbstractOne of the implicit, and sometimes explicit, objectives of modern neuroscience is to find neural correlates of subjective experience so that different qualities of that experience might be explained in detail by reference to the physical structure and processes of the brain. It is generally assumed that such explanations will make unnecessary or rule out any reference to conscious mental agents. This is the classic mind-brain reductivist program. We have chosen to challenge the optimism underlying such an approach in the context of sensory neurophysiology and sensory experience. Specifically, we ask if it is possible to explain the subjective differences among seeing, hearing, and feeling something by inspecting the structure and function of primary visual, auditory, and somesthetic cortex.After reviewing the progress in localization of sensory functions over the past two centuries and examining some aspects of the structure and function of somesthetic, auditory, and visual cortex, we infer that one cannot explain the subjective differences between sensory modalities in terms of present day neuroscientific knowledge. Nor do present trends in research provide grounds for optimism.At this point we turn to three philosophical theories to see what promise they hold of explaining these differences. A brief discussion of each – identity theory, functionalism, and eliminative materialism – suggests that none adequately accounts for the facts of the situation, and we tentatively conclude that some form of dualism is still a tenable hypothesis.
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Shepherd GMG. Intracortical cartography in an agranular area. Front Neurosci 2009; 3:337-43. [PMID: 20198150 PMCID: PMC2796917 DOI: 10.3389/neuro.01.030.2009] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 07/29/2009] [Indexed: 11/23/2022] Open
Abstract
A well-defined granular layer 4 is a defining cytoarchitectonic feature associated with sensory areas of mammalian cerebral cortex, and one with hodological significance: the local axons ascending from cells in thalamorecipient layer 4 and connecting to layer 2/3 pyramidal neurons form a major feedforward excitatory interlaminar projection. Conversely, agranular cortical areas, lacking a distinct layer 4, pose a hodological conundrum: without a laminar basis for the canonical layer 4→2/3 pathway, what is the basic circuit organization? This review highlights current challenges and prospects for local-circuit electroanatomy and electrophysiology in agranular cortex, focusing on the mouse. Different lines of evidence, drawn primarily from studies of motor areas in frontal cortex in rodents, support the view that synaptic circuits in agranular cortex are organized around prominent descending excitatory layer 2/3→5 pathways targeting multiple classes of projection neurons.
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Affiliation(s)
- Gordon M G Shepherd
- Department of Physiology, Feinberg School of Medicine, Northwestern University Chicago, IL, USA
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25
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Abstract
Single neurons in the somatosensory cortex are divisible into a population with receptive fields and a population without receptive fields. These two populations display different laminar distributions, and their respective functions are unknown. We compared other physiological characteristics of these two neuronal populations in an attempt to understand why some neurons lack a receptive field. Only 23% of 465 neurons isolated in the somatosensory cortex of halothane-anesthetized cats displayed a cutaneous receptive field. The iontophoretic administration of glutamate uncovered input from the periphery in another 34% of the sample, leaving 43% of the neurons without evidence of peripheral input under these experimental conditions. Neurons with a receptive field were spontaneously active much more often than neurons lacking peripheral inputs, and their rates of discharge were higher. No differences were found between neurons having a receptive field uncovered with glutamate and those unaffected by glutamate. In all classes of neurons, those cells with spontaneous activity were excited by smaller amounts of glutamate than were silent neurons, but sensitivity to glutamate was not correlated with the presence or absence of a receptive field. We infer that some classes of somatosensory cortical neurons receive strong thalamocortical inputs, whereas others have only relatively weak or no thalamocortical connections. In other experiments we have shown also that those neurons lacking a receptive field and/or spontaneous activity were more likely to be plastic than those with stronger inputs (see Warren and Dykes, 1993a,b), suggesting that neurons having weaker afferent inputs can be more readily modified under certain circumstances.
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Affiliation(s)
- R A Warren
- Department of Neurology and Neurosurgery, McGill University, Montréal, Québec, Canada
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Smith WS, Fetz EE. Synaptic interactions between forelimb-related motor cortex neurons in behaving primates. J Neurophysiol 2009; 102:1026-39. [PMID: 19439672 DOI: 10.1152/jn.91051.2008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated the synaptic interactions between neighboring motor cortex cells in monkeys generating isometric ramp-and-hold torques about the wrist. For pairs of cortical cells the response patterns were determined in response-aligned averages and their synaptic interactions were identified by cross-correlation histograms. Cross-correlograms were compiled for 215 cell pairs and 84 (39%) showed significant features. The most frequently found feature (65/84 = 77%) was a central peak, straddling the origin and representing a source of common synaptic input to both cells. One third of these also had superimposed lagged peaks, indicative of a serial excitatory connection. Pure lagged peaks and lagged troughs, indicative of serial excitatory or inhibitory linkages, respectively, both occurred in 5% of the correlograms with features. A central trough appeared in 13% of the correlograms. The magnitude of the synaptic linkage was measured as the normalized area of the correlogram feature. Plotting the strength of synaptic interaction against response similarity during alternating wrist torques revealed a positive relationship for the correlated cell pairs. A linear fit yielded a positive slope: the pairs with excitatory interactions tended to covary more often than countervary. This linear fit had a positive offset, reflecting a tendency for both covarying and countervarying cells to have excitatory common input. Plotting the cortical location of the cell pairs showed that the strongest interactions occurred between cells separated by <400 microns. The correlational linkages between cells of different cortical layers showed a large proportion of common input to cells in layer V.
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Affiliation(s)
- W S Smith
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195-7290, USA
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Padberg J, Cerkevich C, Engle J, Rajan AT, Recanzone G, Kaas J, Krubitzer L. Thalamocortical connections of parietal somatosensory cortical fields in macaque monkeys are highly divergent and convergent. Cereb Cortex 2009; 19:2038-64. [PMID: 19221145 DOI: 10.1093/cercor/bhn229] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We examined the organization and cortical projections of the somatosensory thalamus using multiunit microelectrode recording techniques in anesthetized monkeys combined with neuroanatomical tracings techniques and architectonic analysis. Different portions of the hand representation in area 3b were injected with different anatomical tracers in the same animal, or matched body part representations in parietal areas 3a, 3b, 1, 2, and areas 2 and 5 were injected with different anatomical tracers in the same animal to directly compare their thalamocortical connections. We found that the somatosensory thalamus is composed of several representations of cutaneous and deep receptors of the contralateral body. These nuclei include the ventral posterior nucleus, the ventral posterior superior nucleus, the ventral posterior inferior nucleus, and the ventral lateral nucleus. Each nucleus projects to several different cortical fields, and each cortical field receives projections from multiple thalamic nuclei. In contrast to other sensory systems, each of these somatosensory cortical fields is uniquely innervated by multiple thalamic nuclei. These data indicate that multiple inputs are processed simultaneously within and across several, "hierarchically connected" cortical fields.
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Affiliation(s)
- Jeffrey Padberg
- Center for Neuroscience, University of California, Davis, Davis, CA, USA
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Tamura Y, Ueki Y, Lin P, Vorbach S, Mima T, Kakigi R, Hallett M. Disordered plasticity in the primary somatosensory cortex in focal hand dystonia. ACTA ACUST UNITED AC 2009; 132:749-55. [PMID: 19151081 DOI: 10.1093/brain/awn348] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Interventional paired associative stimulation (PAS) can induce plasticity in the cortex, and this plasticity was previously shown to be disordered in the primary motor cortex in focal hand dystonia (FHD). This study aimed to test whether associative plasticity is abnormal in the primary somatosensory cortex (S1) in FHD and whether PAS modulates excitatory or inhibitory interneurons within the cortex. Ten FHD patients and 10 healthy volunteers were studied. We investigated the changes in single- and double-pulse somatosensory-evoked potentials before and after PAS, which consisted of peripheral electrical nerve stimulation and subsequent transcranial magnetic stimulation over S1. Four sessions of somatosensory-evoked potentials recordings were performed: before PAS, and immediately, 15 and 30 min after PAS. We compared the time course of the somatosensory-evoked potentials between the FHD and healthy groups. In the single-pulse condition, the P27 amplitudes were significantly higher in FHD immediately after PAS than before PAS, while no changes were observed in healthy subjects. In the double-pulse condition, significant differences in the suppression ratio of P27 were found immediately after and 15 min after PAS, while there were no significant differences in healthy subjects. The P27 suppression tended to normalize toward the level of the healthy volunteer group. In FHD, PAS transiently induced an abnormal increase in excitability in S1. In addition, intracortical inhibition in S1 was found to increase as well. This abnormal plasticity of the intracortical neurons in S1 may contribute to the pathophysiology of dystonia.
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Affiliation(s)
- Yohei Tamura
- Human Motor Control Section, Medical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 10, Room 7D37, 10 Center Drive, MSC 1428, Bethesda, MD 20892-1428, USA.
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Tamura Y, Matsuhashi M, Lin P, Ou B, Vorbach S, Kakigi R, Hallett M. Impaired intracortical inhibition in the primary somatosensory cortex in focal hand dystonia. Mov Disord 2008; 23:558-65. [PMID: 18074393 DOI: 10.1002/mds.21870] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Somesthetic temporal discrimination (STD) is impaired in focal hand dystonia (FHD). We explored the electrophysiological correlate of the STD deficit to assess whether this is due to dysfunction of temporal inhibition in the somatosensory inhibitory pathway or due to dysfunction in structures responsible for nonmodality-specific timing integration. Eleven FHD patients and 11 healthy volunteers were studied. STD threshold was investigated as the time interval required for perceiving a pair of stimuli as two separate stimuli in time. We also examined the somatosensory-evoked potential (SEP) in a paired-pulse paradigm. We compared STD threshold and recovery function of SEP between the groups. STD thresholds were significantly greater in FHD than in healthy volunteers. The amount of P27 suppression in the 5 ms-ISI condition was significantly less in FHD. It was also found that the STD threshold and P27 suppression were significantly correlated: the greater the STD threshold, the less the P27 suppression. Significantly less suppression of P27 with a lack of significant change in N20 indicates that the impairment of somatosensory information processing in the time domain is due to dysfunction within the primary somatosensory cortex, suggesting that that the STD deficit in FHD is more attributable to dysfunction in the somatosensory pathway.
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Affiliation(s)
- Yohei Tamura
- Human Motor Control Section, Medical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-1428, USA
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Bordelon-Glausier JR, Khan ZU, Muly EC. Quantification of D1 and D5 dopamine receptor localization in layers I, III, and V of Macaca mulatta prefrontal cortical area 9: coexpression in dendritic spines and axon terminals. J Comp Neurol 2008; 508:893-905. [PMID: 18399540 DOI: 10.1002/cne.21710] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
D1 family receptors (D1R) in prefrontal cortex (PFC) are critical for normal cognition and are implicated in pathological states such as schizophrenia. The two D1R subtypes, D1 and D5, cannot be pharmacologically distinguished but have important functional differences. To understand their contributions to cortical function, we quantified their localization in the neuropil of primate PFC. We identified different patterns of distribution for the two receptors that showed variation across cortical laminae. Although D1 was enriched in spines and D5 in dendrites, there was considerable overlap in their distribution within neuronal compartments. To determine whether the D1 and D5 receptors are localized to separate populations of synapses, we employed double-labeling methods. We found the two receptors colocalized and quantified the overlap of their distribution in spines and axon terminals of prefrontal cortical area 9 in the Macaca mulatta monkey. The two receptors are found in partially overlapping populations, such that the D5 receptor is found in a subpopulation of those spines and terminals that contain D1. These results indicate that dopamine activation of the two D1R subtypes does not modulate disparate populations of synapses onto dendritic spines in prefrontal cortical area 9; rather, dopamine can activate D1 and D5 receptors on the same spines, plus an additional group of spines that contains only D1. The implications of these results for the dose-dependent relationship between D1R activation and PFC function are discussed.
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31
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Weiler N, Wood L, Yu J, Solla SA, Shepherd GMG. Top-down laminar organization of the excitatory network in motor cortex. Nat Neurosci 2008; 11:360-6. [PMID: 18246064 DOI: 10.1038/nn2049] [Citation(s) in RCA: 234] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Accepted: 01/11/2008] [Indexed: 11/09/2022]
Abstract
Cortical layering is a hallmark of the mammalian neocortex and a major determinant of local synaptic circuit organization in sensory systems. In motor cortex, the laminar organization of cortical circuits has not been resolved, although their input-output operations are crucial for motor control. Here, we developed a general approach for estimating layer-specific connectivity in cortical circuits and applied it to mouse motor cortex. From these data we computed a laminar presynaptic --> postsynaptic connectivity matrix, W(post,pre), revealing a complement of stereotypic pathways dominated by layer 2 outflow to deeper layers. Network modeling predicted, and experiments with disinhibited slices confirmed, that stimuli targeting upper, but not lower, cortical layers effectively evoked network-wide events. Thus, in motor cortex, descending excitation from a preamplifier-like network of upper-layer neurons drives output neurons in lower layers. Our analysis provides a quantitative wiring-diagram framework for further investigation of the excitatory networks mediating cortical mechanisms of motor control.
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Affiliation(s)
- Nicholas Weiler
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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Silberberg G, Grillner S, LeBeau FEN, Maex R, Markram H. Synaptic pathways in neural microcircuits. Trends Neurosci 2005; 28:541-51. [PMID: 16122815 DOI: 10.1016/j.tins.2005.08.004] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2005] [Revised: 06/29/2005] [Accepted: 08/10/2005] [Indexed: 11/21/2022]
Abstract
The functions performed by different neural microcircuits depend on the anatomical and physiological properties of the various synaptic pathways connecting neurons. Neural microcircuits across various species and brain regions are similar in terms of their repertoire of neurotransmitters, their synaptic kinetics, their short-term and long-term plasticity, and the target-specificity of their synaptic connections. However, microcircuits can be fundamentally different in terms of the precise recurrent design used to achieve a specific functionality. In this review, which is part of the TINS Microcircuits Special Feature, we compare the connectivity designs in spinal, hippocampal, neocortical and cerebellar microcircuits, and discuss the different computational challenges that each microcircuit faces.
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Affiliation(s)
- Gilad Silberberg
- Nobel Institute for Neurophysiology, Department of Neuroscience, Karolinska Institutet, S-17177 Stockholm, Sweden
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Miyamoto JJ, Honda M, Saito DN, Okada T, Ono T, Ohyama K, Sadato N. The Representation of the Human Oral Area in the Somatosensory Cortex: a Functional MRI Study. Cereb Cortex 2005; 16:669-75. [PMID: 16079244 DOI: 10.1093/cercor/bhj012] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The tactile sensation of the teeth is involved in various oral functions, such as mastication and speech. Using functional magnetic resonance imaging, we investigated the cortical sensory representation of the oral area, including the teeth. First, we identified the somatotopic representation of the lips, teeth and tongue in the postcentral gyrus (GpoC). Tactile stimuli were applied to the lower lip, tongue and teeth. The foci activated by each stimulus were characterized by the center of gravity (COG) of activated areas. Secondly, we examined the rostro-caudal changes in the somatotopic organization in the GPoC in terms of the overlap between each sensory representation. In the rostral portion of the GPoC, the COG of the representation of teeth was located significantly superior to that of the tongue and inferior to that of the lip, consistent with the classical 'sensory homunculus' proposed by Penfield; however, this somatotopic representation became unclear in the middle and caudal portions of the GPoC. The overlap between each representation in the middle and caudal portions of the GPoC was significantly greater than that in the rostral portion of the GPoC. These findings support the theory that the input from oral structures converges hierarchically across the primary somatosensory cortex.
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Affiliation(s)
- Jun J Miyamoto
- Division of Cerebral Integration, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
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Morel A, Liu J, Wannier T, Jeanmonod D, Rouiller EM. Divergence and convergence of thalamocortical projections to premotor and supplementary motor cortex: a multiple tracing study in the macaque monkey. Eur J Neurosci 2005; 21:1007-29. [PMID: 15787707 DOI: 10.1111/j.1460-9568.2005.03921.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The premotor cortex of macaque monkeys is currently subdivided into at least six different subareas on the basis of structural, hodological and physiological criteria. To determine the degree of divergence/convergence of thalamocortical projections to mesial [supplementary motor area (SMA)-proper and pre-SMA] and lateral (PMd-c, PMd-r, PMv-c and PMv-r) premotor (PM) subareas, quantitative analyses were performed on the distribution of retrograde labelling after multiple tracer injections in the same animal. The results demonstrate that all PM and SMA subareas receive common inputs from several thalamic nuclei, but the relative contribution of these nuclei to thalamocortical projections differs. The largest difference occurs between subareas of SMA, with much greater contribution from the mediodorsal (MD) and area X, and a smaller contribution from the ventral lateral anterior (VLa) and ventral part of the ventral lateral posterior (VLpv) to pre-SMA than to SMA-proper. In PM, differences between subareas are less pronounced; in particular, all receive a significant contribution from MD, the ventral anterior (VApc) and area X. However, there are clear gradients, such as increasing projections from MD to rostral, from VLa and VLpv to caudal, and from dorsal VLp (VLpd) to dorsal premotor subareas. Intralaminar nuclei provide widespread projections to all premotor subareas. The degree of overlap between thalamocortical projections varies among different PM and SMA subareas and different sectors of the thalamus. These variations, which correspond to different origin and topography of thalamocortical projections, are discussed in relation to functional organizations at thalamic and cortical levels.
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Affiliation(s)
- Anne Morel
- Laboratory for Functional Neurosurgery, Neurosurgery Clinic, University Hospital Zürich, Sternwartstrasse 6, CH-8091 Zürich, Switzerland.
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Coq JO, Qi H, Collins CE, Kaas JH. Anatomical and functional organization of somatosensory areas of the lateral fissure of the New World titi monkey (Callicebus moloch). J Comp Neurol 2004; 476:363-87. [PMID: 15282711 DOI: 10.1002/cne.20237] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The organization of anterior and lateral somatosensory cortex was investigated in titi monkeys (Callicebus moloch). Multiunit microelectrode recordings were used to identify multiple representations of the body, and anatomical tracer injections were used to reveal connections. (1) Representations of the face were identified in areas 3a, 3b, 1, S2, and the parietal ventral area (PV). In area 3b, the face was represented from chin/lower lip to upper lip and neck/upper face in a rostrocaudal sequence. The representation of the face in area 1 mirrored that of area 3b. Another face representation was located in area 3a. Adjoining face representations in S2 and PV exhibited mirror-image patterns to those of areas 3b and 1. (2) Two representations of the body, the rostral and caudal ventral somatosensory areas (VSr and VSc), were found in the dorsal part of the insula. VSc was roughly a reversal image of the S2 body representation, and VSr was roughly a reversal of PV. (3) Neurons in the insula next to VSr and VSc responded to auditory stimuli or to both auditory and somatosensory stimuli. (4) Injections of tracers within the hand representations in areas 3b, 1, and S2 revealed reciprocal connections between these three areas. Injections in areas 3b and 1 labeled the ventroposterior nucleus, whereas injections in S2 labeled the inferior ventroposterior nucleus. The present study demonstrates features of somatosensory cortex of other monkeys in titi monkeys, while revealing additional features that likely apply to other primates.
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Affiliation(s)
- Jacques-Olivier Coq
- Vanderbilt University, Department of Psychology, Nashville, Tennessee 37203, USA
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Inui K, Wang X, Qiu Y, Nguyen BT, Ojima S, Tamura Y, Nakata H, Wasaka T, Tran TD, Kakigi R. Pain processing within the primary somatosensory cortex in humans. Eur J Neurosci 2003; 18:2859-66. [PMID: 14656335 DOI: 10.1111/j.1460-9568.2003.02995.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To investigate the processing of noxious stimuli within the primary somatosensory cortex (SI), we recorded magnetoencephalography following noxious epidermal electrical stimulation (ES) and innocuous transcutaneous electrical stimulation (TS) applied to the dorsum of the left hand. TS activated two sources sequentially within SI: one in the posterior bank of the central sulcus and another in the crown of the postcentral gyrus, corresponding to Brodmann's areas 3b and 1, respectively. Activities from area 3b consisted of 20- and 30-ms responses. Activities from area 1 consisted of three components peaking at 26, 36 and 49 ms. ES activated one source within SI whose location and orientation were similar to those of the TS-activated area 1 source. Activities from this source consisted of three components peaking at 88, 98 and 109 ms, later by 60 ms than the corresponding TS responses. ES and TS subsequently activated a similar region in the upper bank of the sylvian fissure, corresponding to the secondary somatosensory cortex (SII). The onset latency of the SII activity following ES (109 ms) was later by 29 ms than that of the first SI response (80 ms). Likewise, the onset latency of SII activity following TS (52 ms) was later by 35 ms than that of area 1 of SI (17 ms). Therefore, our results showed that the processing of noxious and innocuous stimuli is similar with respect to the source locations and activation timings within SI and SII except that there were no detectable activations within area 3b following noxious stimulation.
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Affiliation(s)
- Koji Inui
- Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki 444-8585, Japan.
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Thalamic relay nuclei of the basal ganglia form both reciprocal and nonreciprocal cortical connections, linking multiple frontal cortical areas. J Neurosci 2002. [PMID: 12223566 DOI: 10.1523/jneurosci.22-18-08117.2002] [Citation(s) in RCA: 259] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Thalamic relay nuclei transmit basal ganglia output to the frontal cortex, forming the last link in corticobasal ganglia circuitry. The thalamus regulates cortical activity through differential laminar connections, providing not only feedback, but also initiating "feedforward" loops, via nonreciprocal projections, that influence higher cortical areas. This study examines the organization of thalamic connections with cortex from basal ganglia relay nuclei, including ventral anterior (VA), ventral lateral (VL), and mediodorsal (MD) nuclei, in the Macaque monkey. Anterograde and bidirectional tracer injections ([3H]-amino acids, dextran conjugates of Fluorescein, Lucifer Yellow or FluoroRuby, or wheat germ agglutinin) into discrete VA/VL, MD, and frontal cortical sites demonstrate specific thalamocortical connections. VL projections target caudal motor areas (primary, supplementary, and caudal premotor areas), whereas VA projections target more rostral premotor areas (including cingulate and presupplementary motor areas) and MD projects to dorsolateral and orbital prefrontal cortices. Thalamocortical projections innervate cortical layers I and III, and to a lesser extent, layer V. In motor areas layer I projections are more extensive than those to layer III (and V). The complex laminar organization of projections from specific thalamic sites suggests differential regulation of cortical function. Injections of bidirectional tracers into thalamic and frontal cortical sites also show that in comparison to thalamocortical projections, corticothalamic projections to VA-VL and MD are more widespread. These findings demonstrate both reciprocal and nonreciprocal components to the thalamo-cortico-thalamic relay. Together, these experiments indicate a dual role for VA-VL and MD nuclei: (1) to relay basal ganglia output within specific cortical circuits and (2) to mediate information flow between cortical circuits.
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Abstract
Thalamocortical projections were studied in adult cats using biotinylated dextran amines, wheat germ agglutinin conjugated to horseradish peroxidase, and autoradiography with tritiated leucine and/or proline. The input from 7 architectonically defined nuclei to 14 auditory cortical fields was characterized qualitatively and quantitatively. The principal results were that 1) every thalamic nucleus projected to more than 1 field (range, 4-14 fields; mean, 7 fields); 2) only the projection from the ventral division to some primary fields (primary auditory cortex and posterior auditory cortex) had a periodic, clustered distribution, whereas the input from other divisions to nonprimary areas was continuous; 3) layers III-V received >85% of the total axonal profiles; 4) in most experiments, five or more layers were labeled; 5) the projections to nonprimary auditory areas had many laterally oriented axons; 6) the heaviest input to layer I in all experiments was usually in its upper half, suggesting a sublaminar arrangement; 7) the largest axonal trunks (up to 6 microm in diameter) arose from the medial division and ended in layer Ia, where they ran laterally for long distances; 8) there were three projection patterns: type 1 had its peak in layers III-IV with little input to layer I, and it arose from the ventral division and the dorsal superficial, dorsal, and suprageniculate nuclei of the dorsal division; type 2 had heavy labeling in layer I and less in layers III-IV, arising from the dorsal division nuclei primarily, especially the caudal dorsal and deep dorsal nuclei; and type 3 was a trimodal concentration in layers I, III-IV, and VI that originated chiefly in the medial division and had the lowest density of labeling; and 9) the quantitative profiles with the three methods were very similar. The results suggest that the subdivisions of the auditory thalamus have consistent patterns of laminar distribution to different cortical areas, that an average of five or more layers receive significant input in a specific area, that a given thalamic nucleus can influence areas as far as 20 mm apart, that the first information to arrive at the cortex may reach layer I by virtue of the giant axons, and that several laminar patterns of auditory thalamocortical projection exist. The view that the auditory thalamus (and perhaps other thalamic nuclei) serves mainly a relay function underestimates its many modes for influencing the cortex on a laminar basis.
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Affiliation(s)
- C L Huang
- Division of Neurobiology, Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720-3200, USA.
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Abstract
The flutter sensation is felt when mechanical vibrations between 5 and 50 Hz are applied to the skin. Neurons with rapidly adapting properties in the somatosensory system of primates are driven very effectively by periodic flutter stimuli; their evoked spike trains typically have a periodic structure with highly regular time differences between spikes. A long-standing conjecture is that, such periodic structure may underlie a subject's capacity to discriminate the frequencies of periodic vibrotactile stimuli and that, in primary somatosensory areas, stimulus frequency is encoded by the regular time intervals between evoked spikes, not by the mean rate at which these are fired. We examined this hypothesis by analyzing extracellular recordings from primary (S1) and secondary (S2) somatosensory cortices of awake monkeys performing a frequency discrimination task. We quantified stimulus-driven modulations in firing rate and in spike train periodicity, seeking to determine their relevance for frequency discrimination. We found that periodicity was extremely high in S1 but almost absent in S2. We also found that periodicity was enhanced when the stimuli were relevant for behavior. However, periodicity did not covary with psychophysical performance in single trials. On the other hand, rate modulations were similar in both areas, and with periodic and aperiodic stimuli, they were enhanced when stimuli were important for behavior, and were significantly correlated with psychophysical performance in single trials. Thus, the exquisitely timed, stimulus-driven spikes of primary somatosensory neurons may or may not contribute to the neural code for flutter frequency, but firing rate seems to be an important component of it.
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Curio G. Linking 600-Hz "spikelike" EEG/MEG wavelets ("sigma-bursts") to cellular substrates: concepts and caveats. J Clin Neurophysiol 2000; 17:377-96. [PMID: 11012041 DOI: 10.1097/00004691-200007000-00004] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Somatosensory evoked human EEG and magnetoencephalographic (MEG) responses comprise a brief burst of low-amplitude, high-frequency (approximately 600 Hz) spikelike wavelets ("sigma-bursts") superimposed on the primary cortical response (e.g., the N20 to electrical median nerve stimulation). The recent surge of interest in these macroscopic sigma-burst responses is energized by the prospect of monitoring noninvasively, highly synchronized and rapidly repeating population spikes generated in the human thalamic and cortical somatosensory system. Thus, analyses of spike-related sigma-bursts could uniquely complement conventional low-frequency EEG/MEG, reflecting mass excitatory and inhibitory postsynaptic potentials that potentially also incorporate subthreshold activities of undetermined functional relevance. Recent studies using spatiotemporal source analysis of multichannel recordings identified regional burst sources subcortically (near-thalamic) as well as cortically. At the primary somatosensory cortex, sigma-burst generators showed the well-established homuncular somatotopic ordering. Functionally, the 600-Hz burst appears to comprise multiple subcomponents with differential sensitivity to stimulus rate, intensity, sleep-wake cycle, tactile interference, subject age, and certain movement disorders. A plenitude of cellular candidates contributing to burst generation at different levels can already now be envisaged, including cuneothalamic and thalamocortical relay cells, as well as cortical bursting pyramidal cells and fast-spiking inhibitory interneurons. Although cellular burst coding might serve to relay information with high efficiency, concepts to link macroscopic sigma-bursts and cellular substrates call for additional study.
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Affiliation(s)
- G Curio
- Department of Neurology, Klinikum Benjamin Franklin, Freie Universität, Berlin, Germany
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Huntsman MM, Muñoz A, Jones EG. Temporal modulation of GABA(A) receptor subunit gene expression in developing monkey cerebral cortex. Neuroscience 1999; 91:1223-45. [PMID: 10391431 DOI: 10.1016/s0306-4522(98)00713-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In situ hybridization histochemistry was used to examine the expression of 10 GABA(A) receptor messenger RNAs corresponding to the alpha1-alpha5, beta1-beta3, gamma1 and gamma2 subunits in primary somatosensory and visual areas of macaque monkey cerebral cortex from embryonic day (E) 125 to postnatal day (P) 125. Results were compared with expression patterns in adults. In the sensorimotor cortex at E125, overall levels of all subunit transcripts were low. At E137, there was a major lamina-specific increase in all subunit messenger RNAs except gamma1. For alpha1, alpha2, alpha4, beta2, beta3 and gamma2 subunit transcripts, this increase was highest in areas 3a and 3b, particularly in layers III/IV and VI. Postnatally, there were significant decreases in all transcripts. Alpha1, alpha5, beta2 and gamma2 subunit transcripts, while still at significantly lower levels than at E137, remained expressed at levels higher than other transcripts. Unlike in rodents, there was no obvious "switch" in the major subunits expressed in fetal and adult cortex, alpha1, alpha5, beta2 and gamma2 remaining highest throughout. In area 17, the most prominently expressed subunits at earliest ages were alpha2, alpha5, beta1, beta2, beta3 and gamma2, especially in layers II/III and VI. At E150, expression for alpha2, alpha3, beta1 and beta3 subunit transcripts in these layers decreased, but levels for alpha1, alpha4, alpha5, beta2, gamma1 and gamma2 transcripts increased, particularly within layer IV. The increase at E150 was particularly marked for alpha5 transcripts, which were expressed at levels more than four times those of other transcripts. Alpha1, beta2 and gamma2 remain highest into aduthood. Fetal area 17 displayed lamina-specific patterns of expression not found in adult animals. In particular, alpha3 messenger RNAs were present in layer IVA and gamma1 transcripts were present in layer IVC at E150, despite a lack of expression in these layers in the adult. These data demonstrate increased expression of GABA(A) receptors during the period of establishment of thalamocortical and intracortical connections, and a temporal regulation that may be associated with the period of developmental plasticity.
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Affiliation(s)
- M M Huntsman
- Department of Anatomy and Neurobiology, University of California, Irvine, 92697, USA
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Representation of tactile functions in the somatosensory cortex. ACTA ACUST UNITED AC 1998. [DOI: 10.1016/s0166-4115(98)80068-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Wikström H, Huttunen J, Korvenoja A, Virtanen J, Salonen O, Aronen H, Ilmoniemi R. Effects of interstimulus interval on somatosensory evoked magnetic fields (SEFs): a hypothesis concerning SEF generation at the primary sensorimotor cortex. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s0168-5597(96)95688-9] [Citation(s) in RCA: 161] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
The area 3b hand cortex of adult squirrel monkeys was mapped during the first minutes to hours after transecting the radial and median nerves to the hand. The objective was to evaluate initial cortical reactions to this injury and to determine whether patterns and extents of cortical change are similar in different individuals. There are 5 main findings. First, cortical aggregates related to ulnar nerve inputs from the hand rapidly expanded to occupy an additional 21% of the cortical hand map. Second, face and forearm inputs, which normally activate areas adjacent to hand cortex, rapidly expanded into areas of 4% and 1% of the hand cortex respectively. Third, cortical changes involved shifts in receptive field locations that were initiated within minutes after injury. Fourth, the spatial patterns and extents of cortical change were similar in different individuals. Finally, the pattern of cortical change produced after this injury differed from the pattern seen after injury of the median and ulnar nerves. These rapid expansions are a beginning point from which further changes must progress; however, in contrast to changes accompanying chronic hand injuries, these initial cortical reactions do not appear dictated by use of uninjured inputs.
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Affiliation(s)
- A C Silva
- Department of Anatomy and Neurobiology, Medical College of Ohio, Toledo, USA
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Stepniewska I, Preuss TM, Kaas JH. Thalamic connections of the primary motor cortex (M1) of owl monkeys. J Comp Neurol 1994; 349:558-82. [PMID: 7532193 DOI: 10.1002/cne.903490405] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
To determine the relative contributions of transthalamic cerebellar and pallidal projections to the primary motor cortex (M1) of owl monkeys, we examined the thalamic labeling resulting from injections of fluorescent tracers and wheatgerm agglutinin/horseradish peroxidase conjugate (WGA-HRP) into regions of M1 identified by intracortical microstimulation. Injections were placed in the major somatotopic divisions of M1 (the hindlimb, trunk, forelimb, and face representations) and in the caudal and rostral M1 subareas. In most cases, we injected several differentiable tracers into different parts of M1. Our results indicate that the strongest connections of M1 are with subdivisions of the ventral lateral thalamus (VL); other connections are mainly with intralaminar nuclei (the central lateral, paracentral, and center median nuclei) and the reticular nucleus. Most projections are reciprocal and topographically organized. M1 is strongly connected with the principal (VLp), medial (VLx), and anterior (VLa) subdivisions of the VL complex but has at most weak connections with the dorsal division (VLd). Each of the major somatotopic divisions of M1 is connected with an anteroposteriorly elongated territory within the VL complex. The connections are somatotopically organized such that the M1 hindlimb representation is connected with a band of cells in the lateral and anterior portions of the VL complex (spanning VLa and VLp), whereas the trunk, forelimb, and face representations are connected with successively more medially and posteriorly situated cell bands (spanning VLa, VLp, and VLx). There is some degree of overlap between the somatotopic territories within VL, although the absence of double-labeled cells in cases with injections of adjacent somatotopic divisions of M1 suggests that individual thalamic neurons project to single somatotopic regions. In addition to somatotopic differences, the connections of the caudal and rostral subdivisions of M1 differ to some extent. Caudal M1 is connected most strongly with VLp, a target of cerebellar projections, but it is also connected with VLa, which receives pallidal inputs. In complementary fashion, rostral M1 is most strongly connected with VLa, but it is also connected with VLp. VLx, a target of cerebellar projections, has significant connections with both caudal and rostral M1. These results indicate that all parts of M1 are influenced by both the cerebellum and globus pallidus in owl monkeys, as has been suggested in some recent studies of macaque monkeys.
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Affiliation(s)
- I Stepniewska
- Department of Psychology, Vanderbilt University, Nashville, Tennessee 37240
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Wall JT, Nepomuceno V, Rasey SK. Nerve innervation of the hand and associated nerve dominance aggregates in the somatosensory cortex of a primate (squirrel monkey). J Comp Neurol 1993; 337:191-207. [PMID: 8276997 DOI: 10.1002/cne.903370203] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The cutaneous innervation territories of the median, ulnar, and radial nerves to the hand were determined from neurophysiological recordings of peripheral mechanoreceptor axons in adult squirrel monkeys. These territories were then related to cutaneous receptive fields of cortical area 3b neurons to determine how low-threshold inputs from each hand nerve map onto the primary somatosensory cortex. The results indicate that mechanoreceptor axons in each nerve innervate a continuous skin territory covering about 40% of the hand surface. The total territory of each nerve contains subregions of skin that are either autonomously innervated by that nerve or that receive overlapping innervation from more than one nerve. The autonomous, overlap, and total territories of each nerve are relatively constant from hand to hand. In the area 3b cortex, low-threshold afferents from each nerve provide inputs to aggregates of cortical neurons. The cortical aggregates relating to the median and ulnar nerves are arranged as continuous, rostrocaudally oriented bands, whereas aggregates relating to the radial nerve are discontinuous and more patch-like. Similar patterns of bands and patches, and similar compression ratios of skin/cortical area, are seen across different monkeys. These findings demonstrate that the primary somatosensory cortex of normal adult primates contains bands or patches of neurons that are dominantly activated by low-threshold inputs from specific hand nerves. This approach of delineating nerve territories and their related cortical dominance aggregates provides a useful means of analyzing cortical images of nerves and of quantitating peripheral and central patterns of deprivation after nerve injury.
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Affiliation(s)
- J T Wall
- Department of Anatomy, Medical College of Ohio, Toledo 43699
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Shi T, Stevens RT, Tessier J, Apkarian AV. Spinothalamocortical inputs nonpreferentially innervate the superficial and deep cortical layers of SI. Neurosci Lett 1993; 160:209-13. [PMID: 7504225 DOI: 10.1016/0304-3940(93)90415-h] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Using a combined anterograde and retrograde tracing technique, we examined the distribution pattern of the thalamocortical cells which projected to superficial layers of the hand region of the primary somatosensory cortex (hSI), and quantitatively analyzed the retrogradely labeled cells which putatively contacted terminals of the spinothalamic tract (STT) in the squirrel monkey and the macaque. Less than 25% of the superficial hSI projecting cells were putatively contacted by terminals of cervical enlargement spinothalamic neurons. These cells were primarily located in ventroposterior lateral, ventroposterior inferior and centrolateral nuclei. Although the number of superficial hSI projecting cells numbered less than 20% of the total hSI projecting cells, their patterns of location and their proportion of overlap with STT terminals within each thalamic nucleus were similar. It is suggested that the spinothalamic nociceptive information input to to the cortex equally accesses both superficial and deep SI.
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Affiliation(s)
- T Shi
- Department of Neurosurgery, SUNY Health Science Center, Syracuse 13210
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Albowitz B, Kuhnt U. The contribution of intracortical connections to horizontal spread of activity in the neocortex as revealed by voltage sensitive dyes and a fast optical recording method. Eur J Neurosci 1993; 5:1349-59. [PMID: 8275234 DOI: 10.1111/j.1460-9568.1993.tb00921.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Coronal slices from guinea-pig visual neocortex were stained with voltage-sensitive fluorescence dyes RH414 or RH795. Activity was evoked by electrical stimulation of either the white matter or layer I. Emitted light intensity changes representing summated changes of membrane potential were recorded by a 10 x 10 photodiode array with a temporal resolution of 0.4 ms and a spatial resolution of 94 microns. The distribution and spread of activity in the horizontal direction was analysed. Following stimulation of the white matter or layer I, two regions of activity were differentiated in the medio-lateral direction: a central region (approximately 1 mm wide) of high-amplitude activity close to the stimulation electrode and, distant from the stimulation electrode, peripheral regions of low-amplitude activity. Central and peripheral regions differed in their rates of decline, their relative extent with stimulation of different sites and within different layers. The total extent of non-synaptic evoked activity did not exceed that of the central region of high-amplitude activity. Along the extent of non-synaptic activity, onset latencies of potentials were almost constant. Thus, activity of high amplitude in the central region was likely mediated by simultaneous activation of distributed afferent fibres. In contrast, no non-synaptic activity was found in peripheral regions. Therefore it is suggested that this low-amplitude activity was mediated without direct afferent activation but via long-distance intracortical horizontal pathways. These pathways are known to terminate in layer III, and accordingly latencies of responses in the periphery were shortest in upper cortical layers, whereas in the central region, latencies increased from lower to upper cortical layers.
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Affiliation(s)
- B Albowitz
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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Tsuboi Y, Iwata K, Muramatsu H, Yagi J, Inomata Y, Sumino R. Response properties of primary somatosensory cortical neurons responsive to cold stimulation of the facial skin and oral mucous membrane. Brain Res 1993; 613:193-202. [PMID: 8186967 DOI: 10.1016/0006-8993(93)90899-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The distribution and response characteristics of the primary somatosensory cortical (SI) neurons activated by cold stimulation of the facial skin and oral mucous membrane were studied in cats. The discharge activities of 53 cold-sensitive SI neurons that responded to a decrease in temperature of the facial skin and/or oral mucous membrane were recorded. Each of these neurons was classified according to its responsiveness to mechanical stimulation as follows: LTM (low-threshold mechanoreceptive, 14/53), WDR (wide dynamic range, 39/53) and NS (nociceptive-specific, none identified). Encoding and non-encoding SI cold-sensitive neurons were identified, according to their responsiveness to decremental thermal stimulation. Only 14 cold-sensitive SI neurons demonstrated increased firing frequencies when subjected to incremental stimulus intensity increases and were classified as the encoding-type, whereas 39 non-encoding-type neurons did not.
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Affiliation(s)
- Y Tsuboi
- Department of Physiology, School of Dentistry, Nihon University, Tokyo, Japan
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