bluuebunny/crossref_metadata_2025 huggingface dataset:
Pyramidal neurons of the rat cerebral cortex, immunoreactive to nicotinic acetylcholine receptors, project mainly to subcortical targets
Authors: Bravo Hermes , Karten Harvey J.
Published: January 2005

Cortical neurons immunoreactive to nicotinic acetylcholine receptors (nAChR) of the rat brain were characterized with monoclonal antibodies directed to ACh‐binding subunits (alpha 4) or to ACh‐structural subunits (beta2). A heterogeneous population of nAChR‐LI neurons was found in all cortical regions. The most prominent immunoreactive neurons were pyramids of layers V and II–III. The nonpyramidal positive neurons were fusiform horizontally oriented neurons of layer VIb, small cells of layer I and round or ovoid neurons of layers II–V.

Double labeled experiments (immunohistochemistry and fluorescent retrograde tracers) showed that cholinoceptive pyramidal neurons of layer V project mainly to subcortical targets such as caudate‐putamen, superior colliculus, and pontine nuclei, while very few nAChR positive neurons connect to other cortical areas. These findings suggest that the mainly excitatory effect that has been attributed to the cholinergic innervation upon the cortical neurons may have a greater influence upon the cortico‐subcortical output than the corticocortical one.
Prefrontal cortical efferents in the rat synapse on unlabeled neuronal targets of catecholamine terminals in the nucleus accumbens septi and on dopamine neurons in the ventral tegmental area
Authors: Sesack Susan R. , Pickel Virginia M.
Published: January 2005

Physiological and pharmacological studies indicate that descending projections from the prefrontal cortex modulate dopaminergic transmission in the nucleus accumbens septi and ventral tegmental area. We investigated the ultrastructural bases for these interactions in rat by examining the synaptic associations between prefrontal cortical terminals labeled with anterograde markers (lesion‐induced degeneration or transport of Phaseolus vulgaris leucoagglutinin; PHA‐L) and neuronal processes containing immunoreactivity for the catecholamine synthesizing enzyme, tryosine hydroxylase.

Prefrontal cortical terminals in the nucleus accumbens and ventral tegmental area contained clear, round vesicles and formed primarily asymmetric synapses on spines or small dendrites. In the ventral tegmental area, these terminals also formed asymmetric synapses on large dendrites and a few symmetric axodendritic synapses. In the nucleus accumbens septi, degenerating prefrontal cortical terminals synapsed on spiny dendrites which received convergent input from terminals containing peroxidase immunoreactivity for tyrosine hydroxylase, or from unlabeled terminals. In single sections, some tyrosine hydroxylase‐labeled terminals formed thin and punctate symmetric synapses with dendritic shafts, or the heads and necks of spines. Close appositions, but not axo‐axonic synapses, were frequently observed between degenerating prefrontal cortical afferents and tyrosine hydroxylase‐labeled or unlabeled terminals. In the ventral tegmental area, prefrontal cortical terminals labeled with immunoperoxidase for PHA‐L were in synaptic contact with dendrites containing immunogold reaction product for tyrosine hydroxylase, or with unlabeled dendrites.

These results suggest that: (1) catecholaminergic (mainly dopaminergic) and prefrontal cortical terminals in the nucleus accumbens septi dually synapse on common spiny neurons; and (2) dopaminergic neurons in the ventral tegmental area receive monosynaptic input from prefrontal cortical afferents. This study provides the first ultrastructural basis for multiple sites of cellular interaction between prefrontal cortical efferents and mesolimbic dopaminergic neurons.
Patterns of antigenic expression in the thalamic reticular nucleus of developing rats
Authors: Mitrofanis John
Published: January 2005

The present study describes the development of the thalamic reticular nucleus in rats with the use of Nissl staining and antibodies to parvalbumin and pro‐α‐thyrotropin‐releasing hormone (αTRH). Two major subdivisions of the reticular nucleus are apparent: (1) the main body, which is itself heterogeneous and lies for the most part between the fibres of the internal capsule and external medullary lamina, and (2) the perireticular nucleus, which lies lateral to the main body and medial to the globus pallidus.

In the main body of the reticular nucleus of adults, most cells in all regions are immunoreactive to parvalbumin and αTRH. During development there are two waves of parvalbumin and αTRH expression. The first wave occurs between postnatal day (P) 0 and P10, and labelled cells are apparent in rostrolateral areas of the main body of the nucleus only. At P10, such cells are not apparent. From P7 to adult, there is a second wave of parvalbumin and αTRH expression: labelled cells emerge first in central, then in caudal, and finally in rostral areas of the nucleus.

In adults, the perireticular nucleus is made up of a few small cells which are immunostained for parvalbumin and αTRH. These cells are more frequent in areas of the internal capsule adjacent to the ventral regions of the main body of the reticular nucleus, rostrodorsal to the entopeduncular nucleus. From E (embryonic day) 17 to about P10, the perireticular nucleus consists of a surprisingly large population of neurones, many of which are parvalbumin and αTRH immunoreactive. By about P10, as in adults, there are few perireticular cells.
Somatosensory receptive field properties of corpus callosum fibres in the raccoon
Authors: Guillemot Jean‐Paul , Richer Louis , Ptito Maurice , Guilbert Michel , Lepore Franco
Published: January 2005

Anatomical studies in a number of species have shown that most areas of the somatosensory cortex are callosally interconnected. This is also true for the raccoon, at least for those parts representing proximal and axial body regions. Electrophysiologically, studies carried out in cats and monkeys have demonstrated that all sensory sub‐modalities cross in the callosum. Moreover, cells representing the paws and fingers, though occupying a large portion of areas SI and SII, seem to send proportionately fewer axons through the callosum than axial structures. No comparable study has been carried out in the raccoon. The purpose of the present experiment was therefore to investigate the functional organization of the callosal system in this animal by examining the receptive field properties of the somatosensory fibres crossing in the callosum.

Axonal activity was recorded directly through tungsten microelectrodes in the corpus callosum of eight raccoons. Results indicated that somatosensory information is transmitted in its rostral portion. Most receptive fields concerned axial and proximal body regions and the head and face. Some receptive fields represented para‐axial regions of the body and a few concerned the hands and fingers. Slowly and rapidly adapting fibres were found, as were all the sensory sub‐modalities tested. A substantial proportion of the axons had bilateral receptive fields.

These results are discussed in relation to those obtained in other species, with particular reference to: (1) the midline fusion hypothesis of callosal function; (2) the representation within this structure of the distal extremities, and (3) the origin of the bilateral receptive fields. © 1992 Wiley‐Liss, Inc.
Common synaptic drive to segmentally homologous interneurons in the locust
Authors: Boyan George
Published: January 2005

The aim of the present study was to examine the pattern of synaptic interactions among a set of identified homologous interneurons in the segmental nervous system of the locust.

This paper presents two main findings: first, serially homologous interneurons that are the progeny of neuroblast 7‐4 in the mesothoracic, metathoracic, and first abdominal neuromeres of the locust central nervous system all receive synaptic drive from one and the same presynaptic interneuron. This interneuron has its entire arborization located in these three neuromeres of the central nervous system. It synapses with cells that are siblings, bilateral homologs, and serial homologs, and is itself connected monosynaptically with auditory afferents. The neuronal network that results comprises postsynaptic cells with the same developmental lineage. The second finding is that there is an additional set of synaptic connections among the homologous neurons themselves. All these connections are excitatory, and the pattern of information flow within the network is highly directional. This may relate to the morphologies of the neurons involved and will influence the contribution of homologs from different segments to behavior. © 1992 Wiley‐Liss, Inc.
Ventral pallido‐striatal pathway in the rat brain: A light and electron microscopic study
Authors: Kuo H. , Chang H. T.
Published: January 2005

Most theories of basal ganglia functions have been based on a model circuit in which the flow of information follows a one‐way loop proceeding from the cerebral cortex to the striatum, the pallidum/nigra, the thalamus, and then returns to the cortex. However, this model neglects data from several studies that show a direct feedback projection from the pallidum to the striatum. In this study, we have examined this feedback connection in the ventral striopallidal system to determine the morphology and chemical properties of ventral pallido‐striatal projection neurons and to determine the morphology of ventral pallidal efferents in the ventral striatum.

Fluoro Gold was injected into the ventral striatum to retrogradely label ventral pallidal projection neurons. Substance P immunoreactivity was used as a pallidal marker to delineate the ventral pallidum. The results show that most neurons retrogradely labeled by Fluoro Gold lie in the ventral pallidum. Additional double‐labeling experiments show that none of these Fluoro Gold‐labeled cells are cholinergic neurons; however, some are immunoreactive for parvalbumin, a calcium‐binding protein found in many pallidal neurons. Electron microscopy revealed that the somata and dendrites of these labeled ventral pallidal projection neurons form many synapses with unlabeled terminals. Injection of Phaseolus vulgaris‐leucoagglutinin into the ventral pallidum anterogradely labeled many fibers in the ventral striatum. Electron microscopy revealed that these labeled axons form both symmetric and asymmetric synapses with ventral striatal neurons.

We have thus confirmed that there is a significant direct projection from the ventral pallidum to the ventral striatum. Whether this projection forms a part of either monosynaptic or polysynaptic feedback loops remains to be clarified. Nevertheless, this pallidostriatal projection must be integrated into the theories on basal ganglia functions. © 1992 Wiley‐Liss, Inc.
A new specific antibody reveals octopamine‐like immunoreactivity in cockroach ventral nerve cord
Authors: Eckert Manfred , Rapus Jürgen , Nürnberger Asja , Penzlin Heinz
Published: January 2005

An antiserum was raised in rabbits immunized with octopamine conjugated to thyroglobulin. The specificity of this antiserum for octopamine is shown by dot blot immunoassay analysis. The antiserum does not crossreact with dopamine, noradrenaline, and serotonin, but slight crossreactivity with the amine tyramine at high concentrations was observed. The tyramine crossreactivity could be eliminated by preabsorption with a tyramine‐glutaraldehyde‐BSA conjugate. Using this antiserum, we describe the topographical distribution of octopamine‐immunoreactive (ir) neuronal elements in wholemounts and paraffin sections of the ventral nerve cord of the American cockroach. The pattern of octopamine immunostaining is completely different from that obtained with an antidopamine serum, and can be blocked by preabsorbing the antioctopamine serum with BSA‐conjugated octopamine.

Cell bodies and dendritic processes of putatively octopaminergic dorsal (DUM) and ventral (VUM) unpaired median neurons were clearly octopamine‐ir in all ganglia examined. The numbers of stained DUM somata in the mesothoracic, metathoracic, and terminal ganglion of females correspond to those of peripherally projecting DUM cells revealed previously by retrograde tracing (Gregory, Philos Trans R Soc Lond [Biol] 306:191, 1984; Tanaka and Washio, Comp Biochem Physiol 91A:37, 1988; Stoya et al., Zool Jb Physiol 93:75, 1989). In addition, various, previously unknown, paired cells with octopamine‐like immunoreactivity were found in all ventral ganglia except abdominal ganglia 3–6. Some of these probably project intersegmentally. © 1992 Wiley‐Liss, Inc.
Distribution of protein gene product 9.5 (PGP 9.5) in the vertebrate retina: Evidence that immunoreactivity is restricted to mammalian horizontal and ganglion cells
Authors: Bonfanti Luca , Candeo Paola , Piccinini Marco , Carmignoto Giorgio , Comelli Maria Cristina , Ghidella Silvana , Bruno Renato , Gobetto Armando , Merighi Adalberto
Published: January 2005

Using light microscopic immunocytochemistry, we have studied the distribution of protein gene product 9.5 (PGP 9.5), a neuron‐specific protein first extracted from human brain (Doran et al., '83: J. Neurochem. 40:1542–1547), in the vertebrate retina. Retinas were obtained from frog, chicken, rat, rabbit, cow, cat, dog, and human. No immunoreactivity was observed in frog and only a faint staining was present in chicken. In mammalian retinas, a strong positive reaction was restricted to horizontal and ganglion cells, with minor interspecies variations. Immunostaining was present throughout the cell body and the dendritic tree in horizontal cells. At the level of retinal ganglion cells, immunolabel was particularly abundant in cell bodies and axons forming the optic nerve. Only the main dendrites were stained, the remainder of the dendritic tree giving rise to a diffuse punctate reaction in the inner plexiform layer. In rats, displaced amacrine cells, which are known to contribute largely (40–50%) to the total neuronal population within the ganglion cell layer (Perry, '81: Neuroscience 6:931–944) were not immunoreactive, as demonstrated from (i) analysis of the morphology, cell size and cell density of immunoreactive neurons in wholemounts; (ii) colocalization of retrograde label and PGP 9.5 immunoreactivity in about 80% of ganglion cells after injection of peroxidase into the optic nerve; and (iii) reduction of immunoreactivity in the inner plexiform and ganglion cell layers following optic nerve transection.

Western blot analysis of extracts from rabbit retinas indicated that the immunoreactive species is PGP 9.5 or a closely related molecule. Recent studies have demonstrated that PGP 9.5 is a ubiquitin carboxyl‐terminal hydrolase (Wilkinson et al., '89: Science 246:670–673). The present results, therefore, suggest that differences in the ubiquitination process exist between retinal neurons. © 1992 Wiley‐Liss, Inc.
Neurons in the cockroach nervous system reacting with antisera to the neuropeptide leucokinin I
Authors: Nässel Dick R. , Cantera Rafael , Karlsson Anne
Published: January 2005

Antisera were raised against the myotropic neuropeptide leucokinin I, originally isolated from head extracts of the cockroach Leucophaea maderae. Processes of leucokinin I immunoreactive (LKIR) neurons were distributed throughout the nervous system, but immunoreactive cell bodies were not found in all neuromeres. In the brain, about 160 LKIR cell bodies were distributed in the protocerebrum and optic lobes (no LKIR cell bodies were found in the deuto‐and tritocerebrum). In the ventral ganglia, LKIR cell bodies were seen distributed as follows: eight (weakly immunoreactive) in the subesophageal ganglion; about six larger and bilateral clusters of 5 smaller in each of the throe thoracic ganglia, and in each of the abdominal ganglia, two pairs of strongly immunoreactive cell bodies were resolved. Many of the LKIR neurons could be described in detail. In the optic lobes, immunoreactive neurons innervate the medulla and accessory medulla. In the brain, three pairs of bilateral LKIR neurons supply branches to distinct sets of nonglomerular neuropil, and two pairs of descending neurons connect the posterior protocerebrum to the antennal lobes and all the ventral ganglia. Other brain neurons innervate the central body, tritocerebrum, and nonglomerular neuropil in protocerebrum. LKIR neurons of the median and lateral neurosecretory cell groups send axons to the corpora cardiaca, frontal ganglion, and tritocerebrum. In the muscle layer of the foregut (crop), bi‐ and multipolar LKIR neurons with axons running to the retrocerebral complex were resolved. The LKIR neurons in the abdominal ganglia form efferent axons supplying the lateral cardiac nerves, spiracles, and the segmental perivisceral organs. The distribution of immunoreactivity indicates roles for leucokinins as neuromodulators or neurotransmitters in central interneurons arborizing in different portions of the brain, visual system, and ventral ganglia. Also, a function in circuits regulating feeding can be presumed. Furthermore, a role in regulation of heart and possibly respiration can be suggested, and probably leucokinins are released from corpora cardiaca as neurohormones. Leucokinins were isolated by their myotropic action on the Leucophaea hindgut, but no innervation of this portion of the gut could be demonstrated. The distribution of leucokinin immunoreactivity was compared, to immunolabeling with antisera against vertebrate tachykinins and lysine vasopressin. © 1992 Wiley‐Liss, Inc.
Lamina I spinocervical tract terminations in the medial part of the lateral cervical nucleus in the cat
Authors: Craig A. D. , Broman J. , Blomqvist A.
Published: January 2005

The terminations of spinocervical tract fibers in the lateral cervical nucleus (LCN) of the cat were examined with anterogradely transported Phaseolus vulgaris leucoagglutinin (PHA‐L) in order to analyze their organization relative to the most medial part and the main body (the lateral two‐thirds) of the LCN, which have differential projections and physiological characteristics. Iontophoretic injections of PHA‐L in laminae I–V of the spinal dorsal horn yielded dense labeling in somatotopically appropriate regions of the main body of the LCN, and, as seen previously with horseradish peroxidase, additional terminations were present in the medial LCN after injections at either cervical or lumbar spinal levels. The morphological characteristics of the PHA‐L labeling in these two parts of the LCN were different. Terminations in the lateral LCN consisted of dense clusters of thick fibers bearing large numbers of boutons. The terminal axons in the medial part of the LCN displayed a reticulated network of longitudinally oriented, fine fibers with well‐spaced varicosities. Some of the fine fibers in the medial LCN appeared to be collaterals of thicker fibers that terminated in the lateral LCN.

Injections of PHA‐L that were restricted to lamina I resulted in terminal labeling only in the medial LCN. The labeling was more sparse than that observed in the medial LCN after larger dorsal horn injections but displayed the same morphological characteristics. Lamina I terminations were seen in the medial LCN after cervical or lumbar injections on both the ipsilateral and contralateral sides.

The PHA‐L observations were corroborated by the presence of many retrogradely labeled lamina I cells at both cervical and lumbar spinal levels, following injections of cholera toxin subunit b or rhodamine‐labeled microspheres in the medial LCN. In addition, double‐immunofluorescent labeling for PHA‐L and substance P was performed in a few cases, since substance P immunoreactivity is present in fibers in the medial LCN and also in cell bodies in lamina I; however, very few spinocervical fibers displayed immunoreactivity for both antigens.

These observations indicate that the medial part of the LCN receives input from lamina I neurons, and probably from lamina III‐V neurons as well, at cervical and lumbar spinal levels. The lamina I input to the medial LCN provides a basis for the small population of nociceptive neurons that differentiate the medial LCN. The lamina I input could also be responsible for the general inhibition of lateral LCN neurons by wide‐field noxious stimulation, via activation of GABAergic interneurons in the medial LCN. The present observations in addition indicate that substance P‐immunoreactive fibers in the medial LCN probably represent a modulating supra‐spinal input. © 1992 Wiley‐Liss, Inc.
Tyrosine hydroxylase and acetylcholinesterase in the domestic pig mesencephalon: An immunocytochemical and histochemical study
Authors: Østergaard Karen , Holm Ida E. , Zimmer Jens
Published: January 2005

The mesencephalon of the young domestic pig was studied by tyrosine hydroxylase (TH) immunocytochemistry and acetylcholinesterase (AChE) histochemistry with focus on the substantia nigra (SN), the ventral tegmental area (VTA), and related areas. The purpose was to obtain information on the organization of the mesencephalic, TH immunoreactive (TH‐i), and dopaminergic areas of the pig, in order to provide the necessary background for the possible use of the pig as an alternative large animal experimental model for research on Parkinson's disease, including the use of encapsulated pig dopaminergic neurons for intracerebral xenotransplantation.

Significant findings in the pig, compared to observations in other species, included the presence of prominent bundles of TH‐i dendrites passing in a dorsoventral direction from pars compacta into pars reticulata at middle and caudal levels of the SN, and the presence of a distinct TH‐i substantia nigra pars lateralis (SNL). Caudally in the pig mesencephalon, the retrorubral field (RRF) was found to be very extensive. The view of the RRF, SN, and VTA as parts of the same integrated system was indicated by the crisscrossing of TH‐i dendrites at the transitions between these areas. Estimation of the number of TH‐i neurons in the SN and the VTA showed that these nuclei were of equal size in the pig. Further, it was found that TH‐i nerve cells wore present in the midline between the VTA in the interfascicular and rostral linear groups. TH‐i nerve cells were also present in the otherwise serotoninergic dorsal raphe nuclei, just as other TH‐i cells formed a perirubral cell group.

AChE‐positive neurons were present in both SN and VTA, and appeared to have the same size and morphology as the TH‐i neurons in these areas. Within both nuclei, there were local differences in the AChE staining density, but perhaps more significantly were some marked differences in the structure of the AChE‐positive neuropil of the two areas.

We anticipate that the present description of the cellular organization of the TH‐i dopaminergic areas in the domestic pig ventral mesencephalon will be useful for the development of a nonprimate, large animal, experimental model of Parkinson's diseas. © 1992 Wiley‐Liss, Inc.
Paucity of glutaminase‐immunoreactive nonpyramidal neurons in the rat cerebral cortex
Authors: Kaneko Takeshi , Nakaya Yoshifumi , Mizuno Noboru
Published: January 2005

Glutaminase has been considered to be a synthesizing enzyme of transmitter glutamate in pyramidal neurons of the cerebral cortex. In the present study, an attempt was made to examine with a double immunofluorescence method whether or not nonpyramidal neurons of the cerebral cortex are immunoreactive for glutaminase. Glutaminase was stained with mouse anti‐glutaminase IgM and FITC‐labeled anti‐[mouse IgM] antibody. In the same section, parvalbumin (PA), calbindin (CB), choline acetyltransferase (CAT), vasoactive intestinal polypeptide (VIP), corticotropin releasing factor (CRF), cholecystokinin (CCK), somatostatin (SS), or neuropeptide Y (NPY) was visualized as a marker for nonpyramidal neurons with an antibody to each substance, biotinylated secondary antibody and Texas Red‐labeled avidin. Virtually no glutaminase immunoreactivity was seen in PA‐, CB‐, CAT‐, VTP‐, CRF‐, CCK‐, SS‐, or NPY‐immunoreactive neuronal perikarya in the neocortex and mesocortex (cingulate and retrosplenial cortices), although it was detected in a few PA‐, CB‐, VTP‐, CCK‐, SS‐, or NPY‐immunoreactive nonpyramidal neurons in the piriform, entorhinal, and hippocampal cortices. PA‐ and CB‐positive neurons have been reported to constitute the major population of GABAergic neurons in the cerebral cortex. Thus, the present results, together with the previous reports, suggest that most GABAergic, cholinergic and peptidergic nonpyramidal neurons in the neo‐and mesocortex do not contain glutaminase. © 1992 Wiley‐Liss, Inc.
Effects of advancing age on peripheral nerve regeneration
Authors: Vaughan Deborah Whittaker
Published: January 2005

Following axotomy, the regrowth of peripheral axons takes longer in older individuals than in young ones. The present study compares the crush‐induced process of degeneration and regeneration in the buccal branch of the facial motor nerve in groups of rats aged 3 months and 15 months. Observations are based on qualitative and quantitative analyses of the nerve 20 mm from the site of injury in rats 1, 2, 4, 16, 21, 28, and 56 days after crush. The buccal branch is purely motor and contains a unimodal population of about 1,600 axons commonly in a single fascicle. During the first 28 days post crush (dpc) in the 3‐month animals, the progression of myelin and axon degeneration, myelin clearance, regrowth of axon sprouts, and axon maturation are relatively synchronized and uniform. In the older rats, the degeneration of myelin and axons, myelin clearance, and the appearance of axon sprouts at the site of sample are all delayed. In the younger animals, axon sprouts increase in numbers from their first appearance at 4 dpc through the 2 weeks examined following the restoration of whisking behavior. The numbers of regenerating older axons increase at a rate comparable to that in the younger animals through the time that bilaterally symmetrical whisking behavior is evident, but afterwards the number of axon sprouts decreases. At 2 months after crush the young animals have 30% more fibers in the buccal branch than control nerves, while the older animals have fewer than control numbers. In the 3‐month regenerated nerve, 2 months post crush, 30% of the regenerated fibers are of very small caliber, less than 3 μm2 in cross sectional area, and typically these small axons have unusually thick myelin sheaths; the older nerves do not have such a skewed distribution of axon areas. The older regenerated axons at 2 months post crush have an unusually high density of microtubules compared to the younger regenerated ones (and controls), and the ratio of neurofilaments to microtubules is very low. The conclusions are that motor neurons in older animals regenerate damaged axons after a delay not apparent in the young; the strong regenerative response apparent initially in animals of both age groups is not maintained in the older animals; and the relationship between the numerical density of cytoskeletal elements and the axon cross‐sectional area deviates from normal in the regenerated axons of the older animals. © 1992 Wiley‐Liss, Inc.
Spatial density and immunoreactivity of bipolar cells in the macaque monkey retina
Authors: Martin Paul R. , Grünert Ulrike
Published: January 2005

The anatomical substrates of spatial and color vision in the primate retina are investigated by measuring the immunoreactivity and spatial density of bipolar, amacrine and horizontal cells in the inner nuclear layer of the macaque monkey retina. Bipolar cells can be distinguished from amacrine and horizontal cells by their differential immunoreactivity to antisera against glutamate, glycine, GABA, parvalbumin, calbindin (CaBP D‐28K), and the L7 protein from mouse cerebellum. The spatial density of bipolar cells is compared to the densities of photoreceptors and ganglion cells at different retinal eccentricities.

In the centralmost 2 mm, cone bipolar cells outnumber ganglion cells by about 1.4:1. The density of cone bipolar cells is thus high enough to allow for input to different (parasol and midget) ganglion cell classes by different (diffuse and midget) bipolar cell classes. The density gradient of cone bipolar cells follows closely that of ganglion cells in central retina but falls less steeply in peripheral retina. This suggests that the convergence of cone signals to the receptive fields of ganglion cells in the peripheral retina occurs in the inner plexiform layer. The density of cone bipolar cells is 2.5–4 times that of cones at all eccentricities studied, implying that cone connectivity to bipolar cells remains constant throughout the retina.

Different subgroups of bipolar cells are distinguished by their relative immunoreactivity to the different antisera. All rod and cone bipolar cells show moderate to strong glutamate‐like immunoreactivity. The bipolar cells that show weak to moderate GABA‐like immunoreactivity are also labeled with the antiserum to the L7 protein and are thus identified as rod bipolar cells. Nearly half of all cone bipolar cells showed glycine‐like immunoreactivity. The results suggest that the inhibitory neurotransmitter candidates GABA and glycine are segregated respectively in rod and cone bipolar cell pathways. A diffuse, cone bipolar cell type can be identified by the anti‐parvalbumin and the anti‐calbindin antisera. All horizontal cells show parvalbumin‐like immunoreactivity. Nearly all amacrine cells show GABA‐like or glycine‐like immunoreactivity; a variety of subpopulations also show immunoreactivity to one or more of the other markers used. © 1992 Wiley‐Liss, Inc.
Patterns of glutamate, glycine, and GABA immunolabeling in four synaptic terminal classes in the lateral superior olive of the guinea pig
Authors: Helfert Robert H. , Juiz José M. , Bledsoe Sanford C. , Bonneau Joann M. , Wenthold Robert J. , Altschuler Richard A.
Published: January 2005

The goal of this study was to correlate synaptic ultrastructure with transmitter specificity and function in the lateral superior olive (LSO), a nucleus that is thought to play a major role in sound localization. This was accomplished by means of postembedding immunogold immunocytochemistry. Four classes of synaptic terminals were identified in the LSO. They were distinguishable from one another both morphologically and on the basis of their different patterns of immunolabeling for glutamate, glycine, and γ‐aminobutyric acid (GABA). The highest level of glutamate immunoreactivity was found in terminals that contained round vesicles (R) and formed synaptic contacts with asymmetric synaptic junctions. Round‐vesicle terminals predominated on small caliber dendrites by a ratio of at least 2:1 over the other classes combined. The thinnest dendrites were typically contacted by R terminals only. The ratio of R terminals to the other types decreased as the caliber of the dendritic profiles they apposed increased so that on the soma, R terminals were outnumbered by at least 2:1 by the other types. Terminals containing flattened vesicles (F) exhibited intense immunoreactivity for both glycine and glutamate, although the glutamate immunolabeling was not as high as that in the R terminals. Flattened‐vesicle terminals formed symmetric synaptic contacts with their targets and their distribution was the reverse of that described for R terminals; i.e., they were most abundant on LSO perikarya and fewest on small caliber dendrites. Two terminal types, both containing pleomorphic vesicles and forming symmetric synaptic junctions, were found in far fewer numbers. One group contained large pleomorphic vesicles (LP) and was immunoreactive for both glycine and GABA. The other group contained small pleomorphic vesicles (SP) along with a few dense‐core vesicles and labeled for GABA only. The LP terminals were preferentially distributed on somata and large–caliber dendrites, while the SP terminals most often contacted smaller dendrites. Previous work suggests that a large percentage of the R terminals arise from spherical cells in the ipsilateral cochlear nucleus and are excitatory in action. This pathway may use glutamate as a transmitter. Many of the F terminals are thought to originate from the ipsilateral medial nucleus of the trapezoid body and appear to be the inhibitory (glycinergic) terminals from a pathway that originates from the contralateral ear. The origins and functions of LP and SP terminals are unknown, but a few possibilities are discussed along with the significance of cocontainment of neuroactive substances in specific terminal types. © 1992 Wiley‐Liss, Inc.
Cytoarchitecture and neural afferents of orbitofrontal cortex in the brain of the monkey
Authors: Morecraft R. J. , Geula C. , Mesulam M.‐M.
Published: January 2005

The orbitofrontal cortex of the monkey can be subdivided into a caudal agranular sector, a transitional dysgranular sector, and an anterior granular sector. The neural input into these sectors was investigated with the help of large horseradish peroxidase injections that covered the different sectors of orbitofrontal cortex. The distribution of retrograde labeling showed that the majority of the cortical projections to orbitofrontal cortex arises from a restricted set of telencephalic sources, which include prefrontal cortex, lateral, and inferomedial temporal cortex, the temporal pole, cingulate gyrus, insula, entorhinal cortex, hippocampus, amygdala, and claustrum. The posterior portion of the orbitofrontal cortex receives additional input from the piriform cortex and the anterolateral portion from gustatory, somatosensory, and premotor areas.

Thalamic projections to the orbitofrontal cortex arise from midline and intralaminar nuclei, from the anteromedial nucleus, the medial dorsal nucleus, and the pulvinar nucleus. Orbitofrontal cortex also receives projections from the hypothalamus, nucleus basalis, ventral tegmental area, the raphe nuclei, the nucleus locus coeruleus, and scattered neurons of the pontomesencephalic tegmentum.

The non‐isocortical (agranular‐dysgranular) sectors of orbitofrontal cortex receive more intense projections from the non‐isocortical sectors of paralimbic areas, the hippocampus, amygdala, and midline thalamic nuclei, whereas the isocortical (granular) sector receives more intense projections from the dorsolateral prefrontal area, the granular insula, granular temporopolar cortex, posterolateral temporal cortex, and from the medial dorsal and pulvinar thalamic nuclei. Retrograde labeling within cingulate, entorhinal, and hippocampal cortices was most pronounced when the injection site extended medially into the dysgranular paraolfactory cortex of the gyrus rectus, an area that can be conceptualized as an orbitofrontal extension of the cingulate complex.

These observations demonstrate that the orbitofrontal cortex has cytoarchitectonically organized projections and that it provides a convergence zone for afferents from heteromodal association and limbic areas. The diverse connections of orbitofrontal cortex are in keeping with the participation of this region in visceral, gustatory, and olfactory functions and with its importance in memory, motivation, and epileptogenesis. © 1992 Wiley‐Liss, Inc.
Ultrastructural and immunocytochemical study of lamina II islet cells in rat spinal dorsal horn
Authors: Spike R. C. , Todd A. J.
Published: January 2005

In order to compare the ultrastructure of GABA‐immunoreactive and nonimmunoreactive islet cells in lamina II of the rat dorsal horn, a combined ultrastructural and immunocytochemical study of nine Golgi‐stained neurones was performed. Cell bodies of these neurones were tested with antiserum to GABA, and in most cases with antiserum to glycine, while parts of the cell body and dendritic tree were examined with the electron microscope. Four of the neurones had cell bodies that were immunoreactive with GABA antiserum, and 2 of these were also glycine‐immunoreactive, while 2 were not. Cell bodies of the remaining five neurones were not immunoreactive with GABA antiserum, nor, in the 3 cases tested, with glycine antiserum. Three of the GABA‐immunoreactive cells possessed vesicle‐containing dendrites and were presynaptic at dendrodendritic synapses, whereas no vesicles were observed in the dendrites of any of the neurones that were not GABA‐immunoreactive. The axon of one of the nonimmunoreactive cells was found with the electron microscope. It gave rise to boutons that contained round agranular vesicles and a few dense‐cored vesicles. Three synapses formed by this axon were identified and all were asymmetric. No obvious differences were detected in the types of profile that were presynaptic to GABA‐immunoreactive and nonimmunoreactive cells.

These results suggest that GABAergic islet cells are a source of presynaptic dendrites in lamina II of the rat and that some presynaptic dendrites contain GABA and glycine, while others contain GABA without glycine. The nonimmunoreactive islet cells presumably represent a distinct functional class of neurones and some of these may release an excitatory amino acid transmitter, possibly in addition to one or more neuropeptides. © 1992 Wiley‐Liss, Inc.
Cortical connections of subdivisions of inferior temporal cortex in squirrel monkeys
Authors: Weller R. E. , Steele G. E.
Published: January 2005

Patterns of cortical connections and architectonics were used to determine subdivisions of inferior temporal (IT) cortex of squirrel monkeys. Single or multiple injections of the tracers wheat germ agglutinin‐horseradish peroxidase, Fast Blue, Diamidino Yellow, Fluoro‐Gold, and 3H‐amino acids were placed into IT cortex. Most injections were placed in caudal IT cortex in the region previously shown to receive input from the caudal subdivision of the Dorsolateral Area, DLc; additional injections were placed in more rostral IT cortex. The results indicate the presence of two major regions: a caudal region, ITC, and a rostral region, ITR. An intermediate region of cortex along the ITc−ITR border that displays some connections of ITc and some connections of ITR may be another area. ITc contains a more myelinated dorsal area, ITCd, and a larger ventral area, ITCv. Both ITCd and ITCv receive a major projection from DLC; additional input from DLR, MT, and VII; and send strong projections to ITR, the lateral bank of the superior temporal sulcus, and dorsolateral prefrontal cortex. Only ITCd has strong connections with DLR and cortex in the depths of the superior temporal sulcus, and only ITCv has connections with lateral orbital cortex. The overall pattern of connections between ITC and DLC suggests that ITC has a crude topographic organization, with dorsal cortex representing the lower field and ventral cortex representing the upper field. ITR differs from ITC by receiving little if any input from DLC; projecting to inferior temporal polar cortex, the rostral Sylvian fissure, and medial orbital cortex; and having a less distinct layer IV. Comparison of subdivisions of inferior temporal cortex defined in the present study in squirrel monkeys and those reported in other primates suggests that ITC of squirrel monkeys may correspond to area TEO of macaque monkeys.
Projections of the ventral subiculum to the amygdala, septum, and hypothalamus: A PHAL anterograde tract‐tracing study in the rat
Authors: Canteras N. S. , Swanson L. W.
Published: January 2005

The projections of the ventral subiculum are organized differentially along the dorsoventral (or septotemporal) axis of this cortical field, with more ventral regions playing a particularly important role in hippocampal communication with the amygdala, bed nuclei of the stria terminalis (BST), and rostral hypothalamus. In the present study we re‐examined the projection of the ventral subiculum to these regions with the Phaseolus vulgaris leucoagglutinin (PHAL) method in the rat. The results confirm and extend earlier conclusions based primarily on the autoradiographic method. Projections from the ventral subiculum course either obliquely through the angular bundle to innervate the amygdala and adjacent parts of the temporal lobe, or follow the alveus and fimbria to the precommissural fornix and medial corticohypothalamic tract. The major amygdalar terminal field is centered in the posterior basomedial nucleus, while other structures that appear to be innervated include the piriformamygdaloid area, the posterior basolateral, posterior cortical, posterior, central, medial, and intercalated nuclei, and the nucleus of the lateral olfactory tract. Projections from the ventral subiculum reach the BST mainly by way of the precommissural fornix, and provide rather dense inputs to the anterodorsal area as well as the transverse and interfascicular nuclei. The medial corticohypothalamic tract is the main route taken by fibers from the ventral subiculum to the hypothalamus, where they innervate the medial preoptic area, “shell” of the ventromedial nucleus, dorsomedial nucleus, ventral premammillary nucleus, and cell‐poor zone around the medial mammillary nucleus. We also observed a rather dense terminal field just dorsal to the suprachiasmatic nucleus that extends dorsally and caudally to fill the subparaventricular zone along the medial border of the anterior hypothalamic nucleus and ventrolateral border of the paraventricular nucleus. The general pattern of outputs to the hypothalamus and septum is strikingly similar for the ventral subiculum and suprachiasmatic nucleus, the endogenous circadian rhythm generator. © 1992 Wiley‐Liss, Inc.
Distribution of the 275 kD hair cell antigen and cell surface specialisations on auditory and vestibular hair bundles in the chicken inner ear
Authors: Goodyear R. , Richardson G.
Published: January 2005

The 275 kD hair cell antigen (HCA) is a protein that is specifically associated with the apical surface of sensory hair cells in the chick inner ear. A comparative study of the vestibular and auditory organs of the inner ear, using both wholemounts and cryosections double labelled for the HCA and F‐actin, reveals that two distinct types of hair cells can be distinguished on the basis of antibody staining in each of the vestibular epithelia, One type of hair cell has the HCA restricted to the base of the stereocilia bundle and is found in the striolae of the maculae and in a large, centrally located region of each ampulla. The other type of hair cell is found in the extrastriolar regions of the maculae and the peripheral regions of the ampullae and has the HCA distributed over the entire surface of the stereocilia bundle. In the basilar papilla, the auditory epithelium of the chick inner ear, the HCA is, as in the striolar regions of the maculae, restricted to the base of the hair bundles. In all sensory epithelia the HCA is also present on the apical, nonstereociliary surface of the hair cells. Ultrastructural examination of the basilar papilla and the striolar and the extrastriolar regions of the lagenar macula after staining with ruthenium red and tannic acid shows that there are four morphologically different types of interstereociliary connectors (oblique tip connectors, horizontal tip connectors, shaft connectors and basal connectors) associated with the hair bundles. Oblique tip connectors and basal connectors are found on hair cells from all regions and have a similar distribution. Horizontal tip connectors are seen only on hair cells in the basilar papilla and the striolar region of the lagenar macula. Shaft connectors extend all the way to the tips of extrastriolar hair cell bundles, but extend only a short way up the bundles of hair cells in the basilar papilla and striolar region of the lagenar macula, Immunogold labelling confirms the results obtained with immunofluorescence microscopy and demonstrates that the distribution of the HCA on the surface of adjacent stereocilia correlates closely with that of the shaft connectors; i.e., immunostaining is observed up to the tips of the extrastriolar hair cell bundles, but is restricted to the lower regions of hair cell bundles in the striolar region and basilar papilla. Ruthenium red staining of immunogold labelled preparations further substantiates this correlation between the distribution of shaft connectors and the HCA. The results suggest that the HCA may be a component of a particular type of hair cell surface specialisation that, when present on adjacent the stereocilia, forms one kind of interstereociliary cross‐link, the shaft connector. © 1992 Wiley‐Liss, Inc.
Distribution and structure of identified tonic and phasic synapses between L‐neurones in the locust ocellar tract
Authors: Littlewood P. M. Henk , Simmons Peter J.
Published: January 2005

The ulrastructures and distributions of the discrete anatomical synapses which constitute two distinct types of output connections made by individual ocellar L‐neurones, L1–3, are described. Outputs to neurones L4–5 are excitatory and transmit tonically, whereas reciprocal connections among the three L1–3 neurones are inhibitory and incapable of transmission for longer than a few milliseconds. The tonically transmitting synapses are located in the lateral ocellar tract and are made between the axons of L1–3, which do not receive inputs, and short branches of L4–5, which make no outputs. Each excitatory connection is composed of a few hundred discrete anatomical synapses, each characterised by a bar‐shaped presynaptic density which is 0.15–1.5 m̈m in length and associated with a large number of round synaptic vesicles. Two postsynaptic profiles are apposed to each presynaptic density. Associated with tonic synapses are abundant invaginations of the presynaptic membrane. Synapses of the reciprocal, inhibitory, phasic connections occur in the protocerebral arbors of L1–3, among numerous output synapses of these neurones. Each phasic connection is composed of a few tens of discrete anatomical synapses. Each bar‐shaped presynaptic density is associated with two postsynaptic profiles, and is 0.1–1.0 m̈m long. Compared with the tonic, excitatory connection, there are fewer vesicles and fewer invaginations of the presynaptic membrane associated with each synapse. © 1992 Wiley‐Liss, Inc.
Innervation from the claustrum of the frontal association and motor areas: Axonal transport studies in the cat
Authors: Clascá Francisco , Avendaño Carlos , Román‐Guindo Ana , Llamas Alfonso , Reinoso‐Suárez Fernando
Published: January 2005

The anatomical organization of the projections from the claustrum to the motor and prefrontal cortical areas of the cat's brain was investigated. Both retrograde (single horseradish peroxidase or double fluorochrome deposits in the cortex) and anterograde (peroxidase‐labeled wheat germ agglutinin deposits in the claustrum) tracing techniques were used.

Within the claustrum, the neurons projecting to each sector of the frontal cortex were found to be distributed according to specific patterns of segregation and overlap. Spatial segregation was particularly marked betweenthe cell populations projecting to the various sectors of area 4. The cellsprojecting to the subareas of area 6 and prefrontal cortex displayed a lessmarked but definite segregation. The neuronal populations projecting to some sectors of areas 4, 5, and the primary somatosensory cortex known to contain homotopical representations of the body map were found intermingled in the same small claustral portions. The few double‐labeled neurons found after closely adjacent fluorochrome injections indicates that, in spite of their profuse intracortical branching, claustral axons spread little within the boundaries of a single architectonic area. Anterograde transport experiments showed that claustral fibers end primarily in layers IIIb/IV, VI, and I, whereas layer V is spared. This pattern is homogeneous throughout the frontal cortex.

The possible role of the claustrum as a subcortical site for organized interactions amongst wide arrays of functionally related zones of the cerebral cortex is thereby suggested. © 1992 Wiley‐Liss, Inc.