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E G Jones

Publications and source records attributed to E G Jones.

At least 145 records · Page 8Linked to original sources
PubMed1991

In situ hybridization reveals VIP precursor mRNA-containing neurons in monkey and rat neocortex.

The cDNAs encoding monkey vasoactive intestinal polypeptide (VIP) and PHM-27 and rat VIP and PHI-27 were cloned and used to generate antisense RNA probes. Using in situ hybridization, neurons expressing the VIP/PHM or VIP/PHI precursor mRNAs were localized in monkey and rat somatic sensory and visual cortex. In both neocortical areas of both species, labeled cells were observed in all 6 layers as well as the subcortical white matter.

Amino Acid Sequence↗
PubMed1991

The emergence of architectonic field structure and areal borders in developing monkey sensorimotor cortex.

Adult monkey sensorimotor cortex consists of several structurally and functionally distinct areas. The developmental sequence through which the characteristic architectonic features and the borders of these areas become resolved was examined in a series of fetal, postnatal and adult monkeys by using Nissl staining, cytochrome oxidase and acetylcholinesterase histochemistry, and immunocytochemistry for GABA and the neuropeptides somatostatin, neuropeptide Y, substance P and cholecystokinin. At the youngest fetal age examined (E110), the pre- and postcentral gyri possess six clearly delineated cellular layers; populations of GABA- and neuropeptide-immunoreactive cells can be identified, but their somatic sensory cortex at E110 lacks areal cytoarchitectonic parcellation. Despite the apparent homogeneity in the cytoarchitecture of the somatic sensory cortex, incipient areal borders are revealed by staining for cytochrome oxidase and acetylcholinesterase activity, and by staining immunocytochemically for several neuropeptides. The motor cortex at E110 differs from that in adults by the presence of a prominent layer IV; a clear cytoarchitectonic border between areas 3a and 4 is detectable at E110, which is also revealed by chemoarchitectonic markers. With increasing age, the characteristic architectonic features gradually emerge and areal cytoarchitectonic borders appear, becoming adult-like by early postnatal ages. The gradual changes in cytoarchitecture are paralleled by redistributions of GABA- and neuropeptide-immunoreactive cells and fiber plexuses. The data demonstrate that the progressive refinement in cytoarchitectonic features and in the distributions of neurotransmitter- and peptide-containing cells occurs primarily during the latter third of gestation. The major changes are temporally coincident with the ingrowth of afferent axonal systems, suggesting that the establishment of connectivity may be capable of modulating finer details of structural or molecular phenotype, particularly intra-areal cytoarchitectonic features and neurotransmitter or peptide expression.

Acetylcholinesterase↗
PubMed1991

Distribution and density of GABA cells in intralaminar and adjacent nuclei of monkey thalamus.

The density of GABA-immunoreactive neurons was examined in the intralaminar and certain principal relay nuclei of the macaque monkey thalamus. Counts were made in 10-microns-thick frozen sections and in 1-micron-thick plastic sections and stereological formulae applied to obtain an accurate assessment of the volumetric density of GABA cells in the nuclei. It was found that GABA-immunoreactive cells account for at least 27% of the cells per unit area of all the thalamic nuclei investigated and up to as much as 50% by unit volume. The intralaminar nuclei show only slightly fewer GABA cells than the principal relay nuclei. Previous reports of their absence or relatively low numbers in the intralaminar nuclei probably stem from their smaller size, relatively weaker immunoreactive staining and from failure to apply stereometric formulae that reveal the density of neurons per volume of tissue. These results suggest that the cellular elements of the intralaminar nuclei are not fundamentally different from those of the principal relay nuclei of the thalamus.

Animals↗
PubMed1991

Relationship of intrinsic connections to forelimb movement representations in monkey motor cortex: a correlative anatomic and physiological study.

1. Intracortical microstimulation (ICMS) and horseradish peroxidase (HRP) histochemistry were combined to examine the relationship between intrinsic connections and intracortical microstimulation sites eliciting evoked movements in the forelimb representation of adult macaque monkey motor cortex. 2. The distribution of sites from which stimulation-evoked movements about individual forelimb joints were elicited under anesthesia varied considerably among animals. Identical movements could often be elicited from multiple, noncontiguous sites. 3. After single, small extracellular HRP injections at sites from which thumb movement was evoked, small groups of retrogradely labeled cells and dense patches of axon terminations were found scattered across a wide area of the forelimb representation. Terminal patches were discontinuous and arose from horizontal, intracortical axons. 4. Correlating the HRP labeling with the physiologically defined movement maps revealed a profuse set of intrinsic, bidirectional connections that connect digit representations and representations of movements about the wrist, elbow, and shoulder. 5. HRP injections placed in the forelimb representation close to the physiologically defined face representation resulted in virtually no retrogradely labeled cells or terminal fiber labeling that crossed into the face representation. A patch of anterolaterally placed label that was present may be the dissociated rostrolateral arm area of other authors. 6. Taken together, these data suggest that extensive, horizontally oriented, intrinsic axon collaterals provide inputs to many different forelimb movement representations and may be recruited during complex movements to coordinate the activity of motor cortical zones whose predominant output is to forelimb muscle groups acting synchronously.

Animals↗
PubMed1991

Electrophysiological study of spinothalamic inputs to ventrolateral and adjacent thalamic nuclei of the cat.

1. Extracellular and intracellular methods were used to record from fibers and neurons in the ventral lateral (VL) and adjacent nuclei of the cat thalamus. The receptive fields of the recorded units were analyzed and the units tested for inputs from the medial lemniscus (ML) and spinothalamic tract (STT) by electrical stimulation of the dorsal columns (DC) and ventrolateral funiculus (VLF) at the C2-3 spinal level. 2. Thirty-eight STT fibers were isolated in the thalamus. Their conduction velocities ranged from 15 to 75 m/s (mode 36 m/s). Adequate stimuli were found for 23 of these fibers. Seventeen were low-threshold (LT), 3 were wide-dynamic-range (WDR), and 3 were high-threshold (HT) units. 3. Five STT fibers were intra-axonally injected. Three were sufficiently well filled for analysis of their terminal fields. An intermediate-velocity STT fiber (conduction velocity 38 m/s) had a 4.3-microns axon and a single large terminal field in the central lateral nucleus (CL). The other two STT fibers were smaller, with diameters of 2.5 and 2.3 microns, conduction velocities of 15 and 19 m/s, and terminal fields made up of a few small boutons at the borders of the ventral posterior lateral nucleus (VPL). 4. Of 319 neurons isolated, 14 out of 129 (10.8%) in VL, 14 out of 76 (18.4%) in the VPL or ventral posterior medial (VPM) nucleus, 27 out of 64 (42.2%) in the CL nucleus, and 5 out of 50 (10%) in the reticular nucleus (R) responded at latencies less than 50 ms to VLF stimuli. A train of three pulses was more effective in driving VLF-responding neurons in all these nuclei than a single pulse. VLF-responding cells were widely dispersed in VL, concentrated in a focus in CL, and distributed around the borders of VPL. Most of those in VL and a small number in CL could be antidromically activated by stimulation of motor cortex. 5. Latencies of presynaptic responses (STT fibers) to VLF stimulation were short and varied from 0.8 to 3.9 ms (mode 1.6 ms). Despite this, very few fast-responding neurons were found. These were six VPL neurons (2.5 to 4 ms), one VL neuron (3 ms), and four CL neurons (3-4 ms). The initial spike latencies of the majority of thalamic neurons responding to VLF stimulation appeared in two peaks, one between 6 and 8 ms and the other at 10-15 ms.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1991

Differential gene expression for glutamic acid decarboxylase and type II calcium-calmodulin-dependent protein kinase in basal ganglia, thalamus, and hypothalamus of the monkey.

In situ hybridization histochemistry, using cRNA probes, revealed a complementarity in the distributions of cells in the basal ganglia, basal nucleus of Meynert, thalamus, hypothalamus, and rostral part of the midbrain that showed gene expression for glutamic acid decarboxylase (GAD) or the alpha-subunit of type II calcium-calmodulin-dependent protein kinase (CAM II kinase-alpha). Cells in certain nuclei such as the thalamic reticular nucleus, globus pallidus, and pars reticulata of the substantia nigra show GAD gene expression only; others in nuclei such as the basal nucleus of Meynert, medial mamillary nuclei, and ventromedial hypothalamic nuclei show CAM II kinase-alpha gene expression only. A few nuclei, for example, the pars compacta of the substantia nigra and the greater part of the subthalamic nucleus, display gene expression for neither GAD nor CAM II kinase-alpha. In other nuclei, notably those of the dorsal thalamus, and possibly in the striatum, GAD- and CAM II kinase-expressing cells appear to form two separate populations that, in most thalamic nuclei, together account for the total cell population. In situ hybridization reveals large amounts of CAM II kinase-alpha mRNA in the neuropil of most nuclei containing CAM II kinase-alpha-positive cells, suggesting its association with dendritic polyribosomes. The message may thus be translated at those sites, close to the synapses with which the protein is associated. The in situ hybridization results, coupled with those from immunocytochemical staining for CAM II kinase-alpha protein, indicate that CAM II kinase-alpha is commonly found in certain non-GABAergic afferent fiber systems but is not necessarily present in the postsynaptic cells on which they terminate. It appears to be absent from most GABAergic fiber systems but can be present in the cells on which they terminate. This suggests that the kinase may be differentially engaged in pre- and postsynaptic functions at certain synapses.

Animals↗
PubMed1991

Chemically distinct compartments of the thalamic VPM nucleus in monkeys relay principal and spinal trigeminal pathways to different layers of the somatosensory cortex.

The ventral posteromedial nucleus (VPM) of the monkey thalamus was investigated with combined immunocytochemical, histochemical, and connection-tracing techniques. Injections of anterogradely transported tracers were placed selectively in the caudal nucleus of the spinal trigeminal nuclear complex, and retrogradely transported horseradish peroxidase (HRP) or fluorescent dyes were placed on the surface or into the depths of defined parts of the trigeminal representation in the first somatic sensory area (SI) of the cerebral cortex. The results are correlated with those of the preceding paper (Rausell and Jones, 1991), which demonstrated the presence of 2 domains in the nucleus on the basis of different patterns of cytochrome oxidase (CO) staining and calcium-binding protein immunoreactivity. The cells of the CO-defined rod and matrix domains receive inputs from different components of the trigeminal afferent system and project to different layers of SI. The large- and medium-sized relay cells of the CO-rich rods, which are immunoreactive for parvalbumin, all project to middle layers of SI. The small relay cells of the weakly-stained CO-matrix, surrounding and intervening between the rods, are immunoreactive for 28-kDa calbindin and project to superficial layers (I and II) of SI. Anterograde tracing studies reveal that the rod domain in VPM is innervated by fibers arising in the contra- and ipsilateral principal trigeminal nucleus, while the matrix domain (and calbindin-positive domains in adjacent nuclei) are innervated by fibers arising in the caudal nucleus of the spinal trigeminal complex. These results demonstrate the modularity and parallel streaming of the functional components of the trigeminal part of the somatic sensory system and suggest that lemniscal and nonlemniscal elements of the system gain access by separate routes to different layers of the SI cortex.

Animals↗
PubMed1991

Histochemical and immunocytochemical compartments of the thalamic VPM nucleus in monkeys and their relationship to the representational map.

The ventral posteromedial nucleus (VPM) of the monkey thalamus was investigated with correlative anatomical and physiological techniques. On the basis of staining for cytochrome oxidase (CO), VPM is divided into a lightly stained, background matrix domain and an intensely stained rod domain. The latter consists of elongated rods of large, medium, and small cells, 500 microns wide on average and extending anteroposteriorly, many of them through the full extent of the nucleus. The matrix, consisting of small cells, penetrates between the rods and expands at the dorsomedial, ventrolateral, and posterior aspects of VPM. Multiunit mapping reveals that VPM contains a dorsally situated representation of the contralateral side of the head, face, eye, and interior of the mouth and a medially situated representation of the ipsilateral side of the lips and interior of the mouth, and that the same small region is represented in the same relative position through the full anteroposterior extent of the nucleus. Earlier work had shown that single CO rods contain the representation of the same portion of the periphery throughout their length. The present study suggests that rods in equivalent positions may represent the same portion of the periphery from animal to animal. The cells of the rod and matrix domains show different patterns of immunoreactivity. Virtually all of the large- and medium-sized rod cells are immunoreactive for the calcium-binding protein parvalbumin, and many are stained by the monoclonal antibody CAT 301. Small GABA-immunoreactive cells and terminal-like puncta are highly concentrated in the rods but are dispersed in the matrix. In the matrix, all non-GABA cells are small, immunoreactive for 28-kDa calbindin, and not stained by CAT 301. They appear to form part of a wider system of calbindin-positive cells that extends into adjacent nuclei. The CO rods are indicative of the modularity of the lemniscal component of the trigeminal part of the somatic sensory system at thalamic levels. Thalamocortical relay neurons in this compartment of VPM express a calcium-binding protein and a surface proteoglycan that distinguishes them from relay neurons in the matrix compartment of the nucleus. In the following paper (Rausell and Jones, 1991), the rod and matrix compartments are shown also to have different patterns of input and output connections.

Animals↗
PubMed1991

Differential effects of monocular deprivation on glutamic acid decarboxylase and type II calcium-calmodulin-dependent protein kinase gene expression in the adult monkey visual cortex.

Increases in immunocytochemically detectable type II calcium-calmodulin-dependent protein kinase (CaM II kinase) and decreases in immunocytochemically detectable glutamic acid decarboxylase (GAD) are known to occur in the visual cortex of adult monkeys following brief periods of monocular visual deprivation. In the present study, GAD and CaM II kinase gene expression was investigated under these conditions. The polymerase chain reaction (PCR) was used to generate species-specific cDNA clones that were used to make antisense RNA probes. A second form of CaM II kinase alpha, CaM II kinase alpha-33, which contains an additional phosphorylation consensus sequence, was identified. In situ hybridization in normal visual cortex revealed a complex sublaminar organization of GAD-expressing cells within layers IVC and VI and a distribution of CaM II kinase alpha-expressing cells that was greatest in layers II, III, IVB, and VI. In situ hybridization in the cortex from animals that had been monocularly deprived revealed enhanced CaM II kinase mRNA levels in deprived-eye columns of layer IVC and, associated with the deprived eye, cytochrome oxidase-stained periodicities in other layers. In layer IV, the enhancement of labeling in deprived-eye stripes was, on average, 16% greater than in normal-eye stripes. By contrast, GAD, mRNA levels appeared unchanged in all layers, suggesting a posttranscriptional regulatory mechanism.

Amino Acid Sequence↗
PubMed1990

GABAA receptor immunoreactivity in adult and developing monkey sensory-motor cortex.

The areal and laminar distribution of GABAA receptor immunoreactivity was examined in fetal, early postnatal and adult monkey sensory-motor cortex by using a monoclonal antibody to the purified GABAA receptor complex (Vitorica et al. 1988). GABAA receptor immunoreactivity was distributed throughout the neuropil, often outlining the unstained somata of pyramidal and non-pyramidal cells. In all areas of the adult sensory-motor cortex, layers I-IIIA exhibited the most intense immunostaining. In deeper layers of the four cytoarchitectonic fields of the first somatic sensory area (SI), layers IIIB and V were lightly stained and alternated with somewhat more intensely stained layers IV and VI. In deeper layers of area 4, the deeper half of layer IIIA through layer VA was lightly immunostained, but layers VB and VI were slightly more intensely immunoreactive. A variable number of nonpyramidal cell somata in the cortex and underlying white matter showed immunoreactive staining. GABAA receptor immunoreactivity was present throughout the sensory-motor cortex from the youngest fetal age examined (E121), but the pattern of immunostaining differed from that in the adult. In all areas, the densest immunoreactivity was found in a diffuse band in layers III and IV and in the subplate zone. Within the subplate zone, the presence of receptor immunoreactivity and some intensely stained neuronal somata at all fetal ages suggests the presence of a synaptic neuropil. With increasing age, gradual changes in the distribution of receptor immunoreactivity occurred, resulting in an adult-like pattern of immunostaining by postnatal day 1.5. These results show that laminar pattern of GABAA receptor distribution closely follows the major concentrations of GABA immunoreactive neurons in adults and it is suggested that laminar changes seen in development are associated with the establishment of afferent connections and inhibitory circuits in the sensory-motor cortex.

Aging↗
PubMed1990

Cajal-Retzius neurons in developing monkey neocortex show immunoreactivity for calcium binding proteins.

Immunoreactivity for two calcium binding proteins, 28 kDa calbindin and parvalbumin, was used to label cells morphologically identical to Cajal-Retzius neurons in the developing visual, prefrontal, sensory-motor and temporal cortex of Old World monkeys. At all fetal ages examined (E110-E155), Cajal-Retzius neurons throughout the cortex were immunoreactive for calbindin as well as being acetylcholinesterase positive. Between E130 and E150, the calbindin-immunoreactive Cajal-Retzius cells in the visual cortex, and a few in other cortical areas, also showed parvalbumin immunoreactivity. A reduced population of immunoreactive Cajal-Retzius cells was detected at birth, and none could be visualized by immunocytochemistry or histochemistry at later postnatal ages. Calbindin and parvalbumin immunoreactivity represents a potentially useful marker for this developmentally regulated population of neurons, and the varied expression of the two proteins suggests that Cajal-Retzius neurons may represent a neurochemically heterogeneous cell population.

Acetylcholinesterase↗
PubMed1990

A microcolumnar structure of monkey cerebral cortex revealed by immunocytochemical studies of double bouquet cell axons.

Immunocytochemical methods were used to study 28,000 mol. wt calbindin and tachykinin immunoreactivity in the monkey cerebral cortex. Calbindin and tachykinin immunoreactivity give rise to a generally different pattern of staining of cell bodies and terminal-like puncta. However, the staining of long, vertically-oriented bundles of processes--identical to classical double bouquet cell axonal arborizations--is the most prominent feature of the pattern of both calbindin- and tachykinin-immunoreactive staining. These bundles form a widespread and regular columnar system descending from layer II to layers III-V. The bundles are most evident in layer III where, in tangential sections, they have a density of 7-15 bundles/10,000 microns 2 with a center-to-center spacing of 15-30 microns. The distribution of immunoreactive bundles through the cortex is not homogeneous; somatic sensory, auditory, and visual areas display a large number of calbindin-immunoreactive bundles while tachykinin-immunoreactive bundles are only numerous in the auditory areas and in area 18 of the visual cortex. In the motor cortex (area 4) few or no immunoreactive bundles are visualized with either antibody. Correlative light and electron microscope analysis of tachykinin immunoreactive bundles in the primary auditory cortex shows that the tachykinin-positive axons of the bundles form symmetrical synaptic contacts with dendritic shafts (57%) and spines (43%). Frequently, several immunoreactive boutons that arise from the same fiber are seen climbing along the surfaces of vertically-oriented, non-immunoreactive processes which include myelinated and unmyelinated axons and probably glial processes. The same ultrastructural features and a similar synaptic distribution were found in a previous study [DeFelipe et al. (1989) Brain Res. 503, 49-54] of calbindin-positive bundles in the somatic sensory cortex (areas 3a and 1). Despite the virtually identical morphological features of tachykinin- and calbindin-immunoreactive bundles, colocalization studies demonstrate little coexistence of the two antigens in somata and none in the axonal bundles of double bouquet cells. These data suggest that the double bouquet cell is a chemically heterogeneous, but ubiquitous morphological type of cortical interneuron, whose uniquely bundled axonal system, which is probably GABAergic, imposes a fundamental microcolumnar organization upon the cerebral cortex.

Animals↗
PubMed1990

The role of afferent activity in the maintenance of primate neocorticalfunction.

The major neuronal populations of the primate cerebral cortex can be classified immunocytochemically according to their transmitters and in terms of the differential expression of certain other molecules such as neuropeptides, calcium-binding proteins and protein kinases. We have been able to chart the time course of developmental expression of these molecules and to show that gene expression for many of them is regulated in adult and infant animals by afferent activity entering the cortex. In the visual cortex of adult monkeys, levels of immunocytochemically detectable gamma aminobutyric acid (GABA), of its synthesizing enzyme glutamic acid decarboxylase (GAD) and of the tachykinins are greatly reduced in deprived ocular dominance columns within 24 h of blocking impulse activity in the optic nerve by intraocular injection of tetrodotoxin (TTX). Conversely, levels of immunocytochemically detectable calcium-calmodulin-dependent protein kinase (CAMII kinase) are increased in deprived eye dominance columns. These effects are quickly reversible on restoration of binocular vision, and experiments involving in situ hybridization and S1 nuclease protection assays show that the changes are associated with parallel changes in mRNA levels for preprotachykinin and CAM II kinase, but not for GAD, which appears to be regulated by post-transcriptional mechanisms. Experiments in the primate somatic sensory cortex suggest comparable activity-dependent effects on gene expression there also. It is proposed that effects of this type underlie the establishment of cortical maps during development and their activity-dependent mutability in adulthood.

Afferent Pathways↗
PubMed1990

Correlation and revised nomenclature of ventral nuclei in the thalamus of human and monkey.

The application of histochemical and immunocytochemical methods to the human thalamus, when allied with traditional staining methods, permits a clearer definition of the borders between many nuclei. The findings of electrophysiological and anatomical tracing studies in monkeys can then be correlated with the human material and a nomenclature that is applicable to both monkeys and humans introduced. The ventral nuclei can be divided into four channels relaying pallidal, substantia nigral, cerebellar, and lemniscal information separately to the cerebral cortex. The lemniscal relay is further divided into a proprioceptive component and a cutaneous component, corresponding to Hassler's V.c.e.a. and V.c.e.p nuclei, respectively, and now called VPLa and VPLp.

Animals↗
PubMed1990

Distribution and plasticity of immunocytochemically localized GABAA receptors in adult monkey visual cortex.

Immunocytochemical methods were used to reveal new details of the distribution and plasticity of GABAA receptors in the visual cortex of adult monkeys; the findings were compared with those of autoradiographic experiments involving the binding of 3H-muscimol and 3H-flunitrazepam. In both areas 17 and 18, a monoclonal antibody to the purified GABAA complex (deBlas et al., 1988) produced staining of punctate profiles in the neuropil and around cell bodies and large processes in layers I-VI. The receptor immunostaining was relatively intense in layers II-III, IVA, IVC beta, and VI; these alternated with lightly stained layers I, IVB, IVC alpha, and V. In area 18, the laminar pattern was similar except that layer IV was split into a superficial, lightly stained half and a deep, intensely stained half. In sections cut parallel to the pial surface, receptor distribution in most layers was found to be uniform. There were 3 exceptions in area 17: (1) patches of intense receptor staining were present in layers II and III; (2) a widely spaced, irregular lattice of intense staining was found in layer IVA; and (3) a much finer, regular lattice was present in layer IVC. The patches in layers II-III and the lattice in layer IVA coincided precisely with regions of intense cytochrome oxidase (CO) staining. The binding of 3H-muscimol and 3H-flunitrazepam revealed a laminar pattern that was similar in most respects, including greater ligand binding in layer IVA of area 17, but showed no evidence of the sublaminar organization in layers IVA and IVC beta. Inhomogeneities in receptor immunostaining but not ligand binding were also seen in layer III of area 18. Following a 5 or 10 d period in which intravitreal injections of TTX had silenced ganglion cell activity in one retina, GABAA receptor immunostaining in layer IVC beta was distributed in intensely stained stripes, 450-550 microns wide, that alternated with narrower, lightly stained stripes. Stripes were also seen with receptor immunostaining and with the binding of the 2 radioligands in layer IVC beta of monocularly enucleated monkeys. Comparison with CO staining revealed that the stripes of reduced immunostaining or ligand binding corresponded to columns dominated by the TTX-injected or enucleated eye. Quantitatively, the binding in the deprived eye columns was reduced by 25%.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Synapses of double bouquet cells in monkey cerebral cortex visualized by calbindin immunoreactivity.

In the monkey neocortex, immunoreactivity for the 28-kDa vitamin D-dependent calcium binding protein (Calbindin) is contained in a set of GABAergic intrinsic neurons whose small size and laminar locations render them very distinct from a second set of GABAergic intrinsic neurons that show immunoreactivity for another calcium-binding protein, parvalbumin. A conspicuous feature of many calbindin-immunoreactive cells is their possession of long, vertically oriented bundles of immunoreactive processes that descend or ascend vertically through several cortical layers. These are components of the radial fasciculi of the cortex and are here shown by correlative electron microscopic immunocytochemistry to consist of both immunoreactive dendrites and unmyelinated axons. The morphology of the bundles and the parent cells indicates that the cells are classical double bouquet cells. The calbindin-positive axons in the radial fasciculi in the present study formed symmetric synapses on unlabeled dendritic shafts (62%) and spines (38%). Despite the close-packed nature of the immunoreactive axons, relatively few terminals of the same axon converged on a single postsynaptic profile. The postsynaptic profiles were identified in certain cases as side branches of pyramidal cell apical and basal dendrites. Mainstem apical dendrites generally did not receive synapses derived from the calbindin-positive axons. These results indicate that double bouquet cells can be distinguished both by their GABAergic character and by their possession of calbindin immunoreactivity. They are probably major contributors to the vertical flow of inhibitory influences across laminae of the cerebral cortex.

Animals↗