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S H Hendry

Publications and source records attributed to S H Hendry.

At least 55 records · Page 3Linked to original sources
PubMed1984

Neuropeptide-containing neurons of the cerebral cortex are also GABAergic.

Neurons in the cat and monkey cerebral cortex were stained immunocytochemically for glutamic acid decarboxylase (GluDCase; L-glutamate 1-carboxy-lyase, EC 4.1.1.15), somatostatin (SRIF), neuropeptide Y (NPY), and cholecystokinin octapeptide (CCK). In all areas of cortex examined (somatic sensory, motor, parietal and visual areas), neurons displaying immunoreactivity for each of these molecules were nonpyramidal cells. Co-localization of GluDCase immunoreactivity with peptide immunoreactivity in the same cells was demonstrated by (i) the antibody elution method, staining the same cells by immunofluorescence, first for a peptide and then for GluDCase; (ii) double staining of the same sections with sheep anti-GluDCase and rabbit anti-peptide antisera, the bound antibodies being localized by rhodamine-conjugated donkey anti-sheep and fluorescein-conjugated swine anti-rabbit secondary antisera. With both procedures, cell bodies immunoreactive for GluDCase and for each of the peptides were found in all areas of cortex examined. With double labeling on single sections, it was found that all CCK-, SRIF-, and NPY-immunoreactive cells in cat cortex and 90%-95% in monkey cortex are also GluDCase positive. Many more cells, however, are immunoreactive for GluDCase alone. GluDCase was co-localized with CCK, SRIF, or NPY not only in cell somata, but also in small punctate structures, which are likely to be axon terminals. From the data gained in previous electron microscopic studies, we postulate that neurons displaying GluDCase- and CCK-like immunoreactivity are a class separate from those displaying GluDCase- and SRIF-like immunoreactivity. NPY, however, is co-localized with SRIF immunoreactivity. These results imply that classes of cortical interneuron contain a conventional neurotransmitter (gamma-aminobutyric acid) and a neuromodulator (one of the peptides).

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PubMed1984

Morphology, distribution, and synaptic relations of somatostatin- and neuropeptide Y-immunoreactive neurons in rat and monkey neocortex.

Neurons in the monkey and rat cerebral cortex immunoreactive for somatostatin tetradecapeptide (SRIF) and for neuropeptide Y (NPY) were examined in the light and electron microscope. Neurons immunoreactive for either peptide are found in all areas of monkey cortex examined as well as throughout the rat cerebral cortex and in the subcortical white matter of both species. In monkey and rat cortex, SRIF-positive neurons are morphologically very similar to NPY-positive neurons. Of the total population of SRIF-positive and NPY-positive neurons in sensory-motor and parietal cortex of monkeys, a minimum of 24% was immunoreactive for both peptides. Most cell bodies are small (8 to 10 micron in diameter) and are present through the depth of the cortex but are densest in layers II-III, in layer VI, and in the subjacent white matter. From the cell bodies several processes commonly emerge, branch two or three times, become beaded, and extend for long distances through the cortex. The fields formed by these processes vary from cell to cell; therefore, the usual morphological terms bipolar, multipolar, and so on do not adequately characterize the full population of neurons. Virtually every cell, however, has at least one long vertically oriented process, and most processes of white matter cells ascent into the cortex. No processes could be positively identified with the light microscope as axons. The processes of the peptide-positive neurons form dense plexuses in the cortex. In each area of monkey cortex, SRIF-positive and NPY-positive processes form a superficial plexus in layers I and II and a deep plexus in layer VI. These plexuses vary in density from area to area. All appear to arise from cortical or white matter cells rather than from extrinsic afferents. In some areas such as SI and areas 5 and 7, the superficial plexus extends deeply into layers III and IV; and in area 17, two very prominent middle plexuses occur in layers IIIB through IVB and in the upper one-third of layer V; these are separated by layer IVC, a major zone of thalamic terminations, which contains very few SRIF- or NPY-positive processes. The density of the plexuses is greater for NPY-positive processes than for SRIF-positive processes in all areas. In the rat, the plexuses do not display a strict laminar organization but generally are densest in the supragranular layers (I to III) and decline steadily in the deeper layers.(ABSTRACT TRUNCATED AT 400 WORDS)

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PubMed1983

Thalamic inputs to identified commissural neurons in the monkey somatic sensory cortex.

Commissurally projecting neurons were identified in the monkey first somatic sensory area (SI) by the retrograde axonal transport of horseradish peroxidase (HRP) injected into the contralateral cortex. Neurons identified in this way have large pyramidal somata primarily in layer IIIB of the SI area. Their basal dendrites lie within the terminal plexus of thalamocortical afferents. Electron microscopy was used to examine the synaptic relations of the labelled commissural cells, in particular to determine whether they receive monosynaptic thalamic connections. To do this, retrogradely labelled commissural cells and Golgi-impregnated large pyramidal neurons from layer IIIB were examined ultrastructurally in material in which thalamocortical terminals were degenerating due to a prior lesion of the thalamus. In a significant number of cases degenerating terminals were found to make synapses on the spines or shafts of labelled dendrites. Injections of HRP into SI or into the white matter adjacent to the corpus callosum labelled callosal axons and terminals in the opposite SI. These axons terminated mainly near the somata of the layer IIIB pyramidal cells. Some of their terminals were found to synapse with dendrites receiving synaptic contacts from thalamocortical axon terminals.

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PubMed1983

Morphological diversity of immunocytochemically identified GABA neurons in the monkey sensory-motor cortex.

GABAergic neurons have been identified in monkey sensory-motor cerebral cortex by light microscopic, immunocytochemical localization of the GABA synthesizing enzyme, glutamic acid decarboxylase (GAD). All GAD-positive neurons are non-pyramidal cells. Their somata are present in all layers and are evenly distributed across layers II-VI of the motor cortex (area 4), but are found in greater concentrations in layers II, IV and VI of all areas of first somatic sensory cortex (SI; areas 3a, 3b and 1-2). GAD-positive puncta (putative axon terminals) are present throughout the sensory-motor cortex, and they are found immediately adjacent to the somata, dendrites and presumptive axon initial segments of GAD-negative pyramidal cells. In addition, they are observed in close approximation to the somata of both large and small GAD-positive neurons. In area 4, the density of puncta is highest in the superficial cortical layers (layers I-III) and gradually declines throughout the deeper layers. In SI, the highest densities of puncta are present in layer IV, while moderately high densities are found in layers I-III and VI. In areas 3a and 3b, the puncta in layers IV and VI are particularly numerous and form foci that exhibit greater density than adjacent regions. GAD-positive neurons with large somata, 15-33 micron in diameter, are present in layers IIIB-VI of all areas. Such cells have many primary dendrites that radiate in all directions. In addition they have axons that ascend either from the superficial aspect of the somata or from primary dendrites, and that exhibit horizontal collateral branches. These neurons closely resemble the large basket cells (Marin-Padilla, 1969; Jones, 1975), and they may give rise to many of the GAD-positive endings surrounding the somata and proximal dendrites of pyramidal cells in layers III-VI. In addition, small GAD-positive somata are present in all layers, but they are most numerous in layers II and IIIA of all areas and in layer IV of SI. The somata and proximal dendrites of these cells vary from a multipolar shape with small, beaded dendrites, found primarily in layer IV, to bitufted and multipolar shapes with larger, smooth dendrites. The diversity of somal sizes and locations, the variety of dendritic patterns, and the different distributions of GAD-positive puncta, all combine to suggest that several different morphological classes of intrinsic neurons comprise the GABA neurons of monkey cerebral cortex.

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PubMed1983

Synaptic organization of immunocytochemically identified GABA neurons in the monkey sensory-motor cortex.

Neurons in the monkey somatic sensory and motor cortex were labelled immunocytochemically for the GABA synthesizing enzyme, glutamic acid decarboxylase (GAD), and examined with the electron microscope. The somata and dendrites of many large GAD-positive neurons of layers III-VI receive numerous asymmetric synapses from unlabelled terminals and symmetric synapses from GAD-positive terminals. Comparisons with light and electron microscopic studies of Golgi-impregnated neurons suggest that the large labelled neurons are basket cells. Small GAD-positive neurons generally receive few synapses on their somata and dendrites, and probably conform to several morphological types. GAD-positive axons from symmetric synapses on many neuronal elements including the somata, dendrites and initial segments of pyramidal cells, and the somata and dendrites of non-pyramidal cells. Synapses between GAD-positive terminals and GAD-positive cell bodies and dendrites are common in all layers. Many GAD-positive terminals in layers III-VI arise from myelinated axons. Some of the axons form pericellular terminal nests on pyramidal cell somata and are interpreted as originating from basket cells while other GAD-positive myelinated axons synapse with the somata and dendrites of non-pyramidal cells. These findings suggest either that the sites of basket cell terminations are more heterogeneous than previously believed or that there are other classes of GAD-positive neurons with myelinated axons. Unmyelinated GAD-positive axons synapse with the initial segments of pyramidal cell axons or form en passant synapses with dendritic spines and small dendritic shafts and are interpreted as arising from the population of small GAD-positive neurons which appears to include several morphological types.

Afferent Pathways↗
PubMed1983

Cholecystokinin-immunoreactive neurons in rat and monkey cerebral cortex make symmetric synapses and have intimate associations with blood vessels.

Neurons displaying cholecystokinin-like immunoreactivity (CCK neurons) in rat and monkey cerebral cortex were examined by light and electron microscopic immunocytochemistry. CCK neurons were found to be mainly bipolar cells present in all layers and in all areas of the rat cerebral cortex. CCK neurons were also found in all regions examined in monkey cortex (pre- and post-central gyri and superior parietal lobule). The somata and the dendritic processes of CCK neurons receive relatively few synapses but both symmetric and asymmetric axosomatic and axodendritic synapses were found. The majority of axon terminals displaying CCK-like immunoreactivity formed symmetric synapses, most frequently with the somata and proximal dendrites of pyramidal and nonpyramidal neurons. The somata and processes of CCK neurons were also found to establish very close nonsynaptic associations with blood vessels and with other neurons, suggesting possible roles for the peptide in the maintenance of neuronal excitability and cerebral blood flow.

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PubMed1981

Sizes and distributions of intrinsic neurons incorporating tritiated GABA in monkey sensory-motor cortex.

Neurons accumulating [3H]gamma-aminobutyric acid (GABA) were identified autoradiographically in frozen and plastic sections after injection of the material in the monkey somatic sensory (areas 3, 1, and 2), motor (area 4), and parietal (area 5) cortex following intravenous administration of a GABA transaminase inhibitor, amino-oxyacetic acid. Two general forms of labeled cells are recognized: those with large diameter (15- to 20-micrometer) somata, probably corresponding to the basket cells of Golgi studies, and those with small diameter (6- to 12-micrometer) somata, probably corresponding to several other types. The sizes and laminar distributions of labeled cells in the cytoarchitectonic fields of the first somatic sensory are (SI) are similar. In these areas, the greatest concentrations of labeled cells are in layer II, in layer IV, and in the superficial stratum of layer IV. In area 5, there are many fewer labeled cells in layer IV. In area 4, the labeled cells are larger and distributed more homogeneously, though there are fewer in layer VI. The large labeled cell type is concentrated in layers III and V of all areas. The smaller labeled types are found in all other layers, including layer I. In layer IV, they form approximately 40% of the total small-celled neuronal population.

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PubMed1980

Distribution of callosal fibers around the hand representations in monkey somatic sensory cortex.

Single or multiunit recording of responses to natural peripheral stimuli was used to map the representations of the upper limb and adjacent body parts in the postcentral gyrus of monkeys in which callosally projecting cells and/or axons had been prepared for labeling by previous section of the corpus callosum or contralateral injection of horseradish peroxidase. Subsequent demonstration of electrode tracks in relation to labeled cells and axons showed that no neurons with receptive fields distal to the elbow lay in callosally connected zones, irrespective of the cytoarchitectonic field or body representation in which they lay.

Afferent Pathways↗
PubMed1979

Thalamic relay nuclei for cerebellar and certain related fiber systems in the cat.

Anterograde labeling techniques were used to define the terminal distributions in the thalamus of afferents arising in the deep cerebellar nuclei, entopeduncular nucleus and substantia nigra. Anterograde and retrograde labeling methods were then used to determine the extent of the cortical projections of the cerebellar relay nuclei. The cerebellar projection to the contralateral ventral nuclei of the thalamus terminates in a zone which is separate from that receiving pallido- and nigrothalamic fibers. None of the zones of termination of these fiber systems corresponds to commonly recognized cytoarchitectonic divisions. Instead, they include parts of the ventroanterior (VA), ventrolateral (VL) and principal ventromedial (VMp) nuclei. Some cells within the zone of termination of cerebellar afferents project to parietal cortex (areas 5 and 7). A further, distinct group of cells in this zone projects to motor cortex (area 4). But projections to area 4 also arise from small groups of cells: (a) in the zone receiving nigro- and pallidothalamic fibers; (b) in the part of VL, distinct from the cerebellar terminal zone, in which spinothalamic fibers terminate. Cerebellar, nigral, and entopeduncular fibers also terminate in the intralaminar nuclei. These projections are far greater in extent than those arising in the spinal cord. Some parts of the intralaminar nuclei are dominated by a particular afferent system, while others show substantial overlap of the terminal zone of several afferent systems.

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PubMed1978

Intracortical connectivity of architectonic fields in the somatic sensory, motor and parietal cortex of monkeys.

Anterograde and retrograde transport methods were used to study the corticocortical connectivity of areas 3a, 3b, 1, 2, 5, 4 and 6 of the monkey cerebral cortex. Fields were identified by cytoarchitectonic features and by thalamic connectivity in the same brains. Area 3a was identified by first recording a short latency group I afferent evoked potential. Attempts were made to analyze the data in terms of: (1) routes whereby somatic sensory input might influence the performance of motor cortex neurons; (2) possible multiple representations of the body surface in the component fields of the first somatic sensory area (SI). Apart from vertical interlaminar connections, two types of intracortical connectivity are recognized. The first, regarded as "non-specific," consists of axons spreading out in layers I, III and V-VI from all sides of an injection of isotope; these cross architectonic borders indiscrimininately. They are not unique to the regions studied. The second is formed by axons entering the white matter and re-entering other fields. In these, they terminate in layers I-IV in one or more mediolaterally oriented strips of fairly constant width (0.5--1 mm) and separated by gaps of comparable size. Though there is a broadly systematic topography in these projections, the strips are probably best regarded as representing some feature other than receptive field position. Separate representations are nevertheless implied in area 3b, in areas 1 and 2 (together), in areas 3a and 4 (together) and in area 5; with, in each case, the representations of the digits pointed at the central sulcus. Area 3b is not connected with areas 3a or 4, but projects to a combined areas 1 and 2. Area 1 is reciprocally connected with area 3a and area 2 reciprocally with area 4. The connectivity of area 3a, as conventionally identified, is such that it is probably best regarded not as an entity, but as a part of area 4. Areas identified by others as area 3a should probably be regraded as parts of area 3b. Parts of area 5 that should be more properly considered as area 2, and other parts that receive thalamic input not from the ventrobasal complex but from the lateral nuclear complex and anterior pulvinar, are also interconnected with area 4. More posterior parts of area 5 are connected with laterally placed parts of area 6. A more medial part of area 6, the supplementary motor area, occupies a pivotal position in the sensory-motor cortex, for it receives fibers from areas 3a, 4, 1, 2 and 5 (all parts), and projects back to areas 3a, 4 and 5.

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PubMedDate not supplied

Selective expression and rapid regulation of GABAA receptor subunits in geniculocortical neurons of macaque dorsal lateral geniculate nucleus.

Monocular deprivation in adult macaques produces a rapid down-regulation in GABA and GABAA receptor subunit immunoreactivity in deprived-eye columns of primary visual cortex (VI) but a significantly delayed GABA reduction in deprived layers of the dorsal lateral geniculate nucleus (LGN). These findings, suggesting that normal inhibitory neurotransmission persists in LGN at a time when VI inhibitory mechanisms are greatly altered, are consistent with physiological studies that have demonstrated a greater degree of functional plasticity in VI than in LGN. Nonetheless, functional adaptation to partial loss of visual input has been detected in the LGN, indicating that synaptic plasticity takes place in this nucleus. In the present study, evidence for early changes in inhibitory neurotransmission were examined with immunocytochemical methods to determine if, in the absence of early GABA regulation, GABAA receptor subunits in macaque LGN are affected by adult deprivation. Immunoreactivity for alpha 1 and beta 2/3 subunits of the GABAA receptor was intense within the magnocellular layers and more modest in the parvocellular layers and intercalated layers. In all layers, immunoreactivity was present in the cytoplasm and along the surfaces of relatively large somata and in dense tangles of processes in the neuropil. Double-labeling experiments demonstrated that somata and processes immunoreactive for alpha 1 and beta 2/3 were surrounded by GABA terminals but no cell intensely immunoreactive for either subunit expressed immunoreactivity for GABA, itself. Following periods of monocular deprivation by tetrodotoxin (TTX) injection for 4 days or longer, layers deprived of visual activity displayed levels of alpha 1 and beta 2/3 immunoreactivity markedly lower than those displayed by the adjacent, normally active layers. Such changes were greater as the period of deprivation increased. The changes included a loss of immunostaining in and around somata and in many neuropil elements of deprived layers. These data indicate that GABA and GABAA receptor subunits alpha 1 and beta 2/3 are expressed by separate populations of neurons in macaque LGN that are differentially regulated by visual activity. The findings suggest that rapid, activity-dependent regulation of postsynaptic receptors represents one mechanism for altering synaptic strength in the adult macaque visual system.

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PubMedDate not supplied

Neurochemical compartmentation of monkey and human visual cortex: similarities and variations in calbindin immunoreactivity across species.

The compartmental organization of visual cortical neurons was examined across species of primates by directly comparing the pattern of immunoreactivity for the 28-kD vitamin D-dependent calcium-binding protein (calbindin) in area 17 of squirrel monkeys, macaques, and neurologically normal adult humans. Area 17 of macaques and squirrel monkeys was similar in that somata and processes intensely immunoreactive for calbindin were present in the same layers (II-III, IVB, and V) and in both species formed a well-stained matrix that surrounded the CO-rich puffs in layer III. These intensely calbindin-immunoreactive neurons were identified as subpopulations of GABA-immunoreactive neurons. Among the most obvious differences in the two monkey species was the distribution of calbindin-positive elements outside of layer III: a dense immunostained matrix surrounded the puffs in layers II, IVB, V, and VI of squirrel monkeys but the immunostained neurons adopted no regular pattern outside layer III in macaques. In addition, although somata lightly immunoreactive for calbindin were present in both species, they were much more abundant in squirrel monkeys than macaques. The pattern of calbindin immunostaining in human area 17 resembled that of macaques in forming an intense matrix that surrounded puffs only in layer III, yet also resembled that of squirrel monkeys by including large numbers of light immunoreactive somata. These lightly immunostained somata included a very dense population forming a prominent band in layer IVA of human visual cortex. We conclude that for layer III of primary visual cortex, a similar pattern of neuronal chemistry exists across species of primates which is related to this layer's compartmental organization. Yet for other layers, the expression of calbindin immunoreactivity varies from one species to the next, perhaps reflecting variations in other neuronal properties.

Aged↗
PubMedDate not supplied

Monoclonal antibody that identifies subsets of neurones in the central visual system of monkey and cat.

Striking correlations between structure and function are found in the visual cortex of Old World primates. These include the co-localization of glutamic acid decarboxylase (GAD, the biosynthetic enzyme of the inhibitory neurotransmitter, gamma-aminobutyric acid) with the mitochondrial enzyme, cytochrome oxidase (CO) in functionally distinct subcompartments of ocular dominance columns. We report here immunocytochemical studies with a monoclonal antibody (CAT 301) showing that the antibody recognizes an uncharacterized antigen on surfaces of some neurones in certain layers of the monkey striate cortex (area 17), and in certain parts of the cat and monkey dorsal lateral geniculate nuclei (LGN). Patches of immunocytochemically stained neurones and neuropil, apparent in layers III, IVB and VI of the striate cortex of normal monkeys, become even more clearly delineated in animals from which one eye has been removed. The antibody-stained patches in the three layers line up radially with one another in lines passing through the centres of ocular dominance columns (demonstrable by CO staining in layers IVA and IVC). In layers III and VI the patches coexist with CO-positive patches and, in the horizontal dimension, both antibody and CO-positive patches are aligned to form rows. Stained neurones in the monkey LGN are primarily in the magnocellular layers and in the cat LGN are confined to laminae A and A1, the inter-laminar plexuses, the perigeniculate nucleus and the medial inter-laminar nucleus. The antigen we have localized is associated with particular cell populations, some of which may correspond to a specific, physiological class.

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