bluuebunny/crossref_metadata_2025 huggingface dataset:
Density of neurons and synapses in the cerebral cortex of the mouse
Authors: Schüz Almut , Palm Günther
Published: January 2005

Quantitative anatomical investigations provide the basis for functional models. In this study the density of neurons and synapses was measured in three different areas (8, 6, and 17) of the neocortex of the mouse. Both kinds of measurements were made on the same material, embedded in Epon/Araldit. In order to determine the synaptic density per mm3, the proportion of synaptic neuropil was also measured; it was found to be 84%. The cortical volume occupied by cell bodies of neurons and glia cells amounted to 12%, that by blood vessels to 4%.

The total average was 9.2 × 104 neurons/mm3 and 7.2 × 108 synapses/mm3. About 11% of the synapses were of type II. The density of neurons increased with decreasing cortical thickness; thus the number of neurons under a given surface area was about constant. The synaptic density, on the other hand, was almost constant in the three areas, the number of synapses under a given cortical surface area tended, therefore, to increase with cortical thickness. The average number of synapses per neuron was 8,200, with a tendency to increase with increasing cortical thickness.

Shrinkage of the tissue was also measured for various staining techniques. No shrinkage occurred during perfusion with 3.7% formaldehyde or with a solution of buffered paraformaldehyde and glutaraldehyde and during fixation in situ. Electron microscopical material showed almost no shrinkage, whereas Nissl‐preparations on paraffin‐embedded material had only 43% of their original volume. After Nissl stain on frozen sections the volume had shrunken to 68% and after Golgi impregnation and embedding in celloidin to 70%. The total volume of the neocortex was 112 mm3 (both hemispheres together). The total number of neurons was thus 1.0 × 107 and the total number of synapses 8.1 × 1010.
Prenatal development of retinocollicular projections in the rabbit: An HRP study
Authors: Crabtree John W.
Published: January 2005

The prenatal development of the rabbit's retinal projections to the superior colliculus (SC) was studied by using anterograde transport of horseradish peroxidase injected intraocularly. Fetuses aged embryonic day 21 (E21) to E29 and an adult rabbit were examined. Gestation in the rabbit is 30–31 days. On E21 contralaterally projecting retinal fibers invade across the entire SC. Their distribution is initially diffuse within the superficial laminae, but by E29 they have a distinct stratified appearance. Ipsilaterally projecting retinal fibers invade the rostral half of the SC on E21. By E23 they cover the entire SC and overlap the contralateral fibers both tangentially and radially. The ipsilateral fibers for the most part are sparsely distributed, but they form a dense focal distribution in the rostrolateral quarter of the SC. This focus straddles the stratum griseum superficiale/stratum opticum (SGS/SO) border. On E25 the ipsilateral fibers maintain their widespread distribution and focal rostrolateral concentration. By E27 they are excluded almost entirely from the caudal half of the SC and are reduced in density in the rostromedial quarter of the nucleus. On E29 the ipsilateral terminal field forms distinct patches and bands that are restricted to the rostrolateral quarter of the SC and are confined to the SGS/SO border. Thus, a few days before birth the pattern and location of the ipsilateral retinocollicular projection resemble those seen in the adult. The early widespread distribution of the ipsilaterally projecting retinal fibers to the SC and their eventual restriction in the fetal rabbit are consistent with the development of this projection in other mammalian orders.
Avian somatosensory system: II. Ascending projections of the dorsal column and external cuneate nuclei in the pigeon
Authors: Wild J. Martin
Published: January 2005

The ascending projections of the dorsal column and external cuneate nuclei (DCN/CuE) in the pigeon were investigated in anterograde tracing experiments by using autoradiography or wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP). The results show that the majority of ascending projections decussate via internal arcuate fibers to form a contralateral medial lemniscus which ascends in a ventral position. In the brainstem, terminal fields were observed in the ventral lamella of the inferior olive (OI), the parabrachial nuclei (PB) of the dorsolateral pons, the intercollicular nucleus (ICo) of the midbrain, and the nucleus pretectalis diffusus (PD). In the diencephalon there were terminal fields in the strata cellulare externum and internum (SCE and SCI) of the caudal hypothalamus; in the intercalated (ICT), ventrolateral (VLT), and reticular nuclei of the ventral thalamus; in the nuclei principalis precommissuralis (PPC), spiriform medialis (SpM), and dorsolateralis posterior, pars caudalis (cDLP) of the caudal thalamus; and in the nuclei dorsalis intermedius ventralis anterior (DIVA), dorsolateralis posterior, pars rostralis (rDLP), dorsolateralis anterior (DLA), and dorsolateralis anterior, pars medialis (DLM) of the rostrodorsal thalamus.

The origins of these projections within the DCN/CuE complex were verified in retrograde tracing experiments with WGA‐HRP and were found to be partly differentiable with respect to their targets. The projections to DIVA, rDLP, DLA, DLM, cDLP, and SpM arise from all rostrocaudal levels of the DCN/CuE complex; those to ICo arise from caudomedial nuclear regions, while those to the hypothalamus and ventral thalamus arise from rostrolateral nuclear regions. Projections to PB arise from lamina I neurons of the dorsal horn of upper cervical spinal cord segments and from CuE. No evidence was found of a projection to the cerebellum.

The distribution of the cells of origin of the medial lemniscus (ML) within the DCN/CuE complex was found to be largely coextensive with the areas of termination of primary spinal (Wild: J. Comp. Neurol. 240:377–395, '85) and some trigeminal (Dubbledam and Karten: J. Comp. Neurol. 180:661–678, '78) afferents. Furthermore, the areas of termination of the ML within the rostrodorsal and caudal thalamus are also either coextensive or closely associated with nuclei which provide a somatosensory projection to separate regions of the telencephalon (Wild: Brain Res. 412:205–223, '87). There are thus clear similarities in the overall pattern of somatosensory projections in the pigeon and in many mammalian species.
Neuronal localization of cholecystokinin mRNA in the rat brain by using in situ hybridization histochemistry
Authors: Ingram Susan M. , Krause Rudolph G. , Baldino Frank , Skeen Leslie C. , Lewis Michael E.
Published: January 2005

The distribution of cholecystokinin (CCK) mRNA in the rat brain was determined by means of in situ hybridization histochemistry. Our results demonstrate a widespread distribution of neurons containing CCK mRNA throughout the rat brain. Hybridization‐positive neurons were distributed throughout the neocortex, olfactory bulb, claustrum, amygdala, the dentate gyrus and hippocampus proper, and several subnuclei of the thalamus and the hypothalamus. The most abundant and most heavily labeled neurons were found in the endopiriform/piriform cortex, tenia tecta, and the ventral tegmental area. The distribution of neurons positive for CCK mRNA paralleled that of CCK‐like immunoreactive neurons. These results detail the distribution of CCK mRNA and clearly identify the existence of CCK‐synthesizing neurons in regions such as the paraventricular and supraoptic nuclei of the hypothalamus, where the presence of CCK cell bodies was previously uncertain.
Relationship between isthmotectal fibers and other tectopetal systems in the leopard frog
Authors: Gruberg Edward R. , Wallace Mark T. , Waldeck Robert F.
Published: January 2005

We studied the relationship of isthmotectal input to other tectal afferent fiber systems in three ways. (1) Using horseradish peroxidase (HRP) histochemistry, we determined the nonretinal inputs to the superficial tectum. In different sets of animals we (a) applied HRP to the tectal surface; (b) inserted HRP crystals into the tectum; (c) injected small volumes of HRP solutions into the superficial tectum. N. isthmi accounts for more than 65% of the nonretinal extrinsic input in the superficial tectal layers. One set of fibers from the contralateral n. isthmi projects to the most superficial layer. Fibers from posterior thalamus and tegmentum project to both superficial and deeper layers in the tectum, but not to the most superficial layer. The ipsilaterally projecting isthmotectal fibers terminate in the deeper superficial layers. (2) We investigated the relationship between retinofugal and contralaterally projecting isthmotectal pathways. We orthogradely labelled n. isthmi fibers by unilateral HRP injections into n. isthmi, and we also labelled retinal fibers by injecting tritiated 1‐proline into both eyes. In such animals contralaterally projecting isthmotectal fibers cross in the dorsal posterior region of the optic chiasm. From the chiasm to the tectum isthmotectal fibers and retinofugal fibers are admixed. (3) We determined whether other fiber systems cross with contralaterally projecting isthmotectal fibers. We cut the posterior part of the optic chiasm and applied HRP crystals to the cut. Only n. isthmi and retina are retrogradely labelled.
Axonal trajectories and terminations of on‐ and off‐cells in the cat lower brainstem
Authors: Mason P. , Fields H. L.
Published: January 2005

Two physiologically defined classes of pontomedullary raphe neurons were intracellularly labeled in order to determine the target nuclei of their axonal projections. In the lightly anesthetized cat, cells either increased (on‐cells) or decreased (off‐cells) their discharge rate during the paw withdrawal reflex evoked by noxious pinch or heat. On‐ and off‐cells were injected with horseradish peroxidase and the initial course of labeled axons through the lower brainstem was reconstructed.

On‐cell projections to the pontomedullary raphe and medial reticular nuclei were sparse. On‐cells projected densely to regions of the lateral reticular formation and the ventrolateral medulla at both rostral and caudal medullary levels. In general, on‐cells had few collaterals and sparse axonal swellings.

In contrast to on‐cells, most off‐cells had axons that collateralized densely within the brainstem raphe and adjacent reticular formation. Such collaterals were either local, within the neuron's dendritic field, or distant, involving a projection of 1–8 mm. One off‐cell had a dense terminal field within the sensory trigeminal complex, a projection that may subserve the inhibition of trigeminal sensory neurons produced by raphe magnus stimulation. Well‐labeled off‐cells had numerous collaterals and dense regions of axonal swellings.

In summary, off‐cells terminated densely in the raphe magnus and adjacent reticular formation whereas on‐cells projected predominantly to the ventrolateral medulla, a region implicated in autonomic control. Local off‐cell collaterals provide an anatomical substrate that would enable off‐cells to coordinate the activity of on‐ and off‐cells through synaptic contacts.
Distribution of cat‐301 immunoreactivity in the frontal and parietal lobes of the macaque monkey
Authors: McGuire Philip K. , Hockfield Susan , Goldman‐Rakic Patricia S.
Published: January 2005

The distribution of the monoclonal antibody Cat‐301 was examined in the frontal and parietal cortex of macaque monkeys. In both regions the distribution was uniform within cytoarchitecturally defined areas (or subareas) but varied between them. In all areas, Cat‐301 labeled the soma and proximal dendrites of a restricted population of neurons. In the frontal lobe, Cat‐301‐positive neurons were intensely immunoreactive and present in large numbers in the motor cortex (area 4), premotor cortex (area 6, excluding its lower ventral part), the supplementary motor area (SMA), and the caudal prefrontal cortex (areas 8a, 8b and 45). In the parietal lobe, large numbers of intensely immunoreactive neurons were evident in the post‐central gyrus (areas 1 and 2), the superior parietal lobule (PE/5), and the dorsal bank (PEa), fundus (IPd), and deep half of the ventral bank (POa(i)) of the intraparietal sulcus (IPS).

Two major patterns of laminar distribution were evident. In motor, supplementary motor, premotor (excluding the lower part of its ventral division), and the caudal prefrontal cortex (Walker's areas 8a, 8b and 45), and throughout the parietal cortex (with the exception of area 3), Cat‐301‐positive neurons were concentrated in the lower part of layer III and in layer V. The laminar positions of labeled cells in these areas were remarkably constant, as were the proportions of labeled neurons that had pyramidal and nonpyramidal morphologies (means of 30.2% and 69.8%, respectively). In contrast, in prefrontal areas 9, 10, 11, 12, 13, 14, and 46, in the cingulate cortex (areas 23, 24 and 25), and in the lower part of the ventral premotor cortex, Cat‐301‐positive neurons were spread diffusely across layers II to VI and a mean of 3.6% of the labeled neurons were pyramidal while 96.4% were nonpyramidal. Area 3 was unique among frontal and parietal areas, in that the labeled neurons in this area were concentrated in layers IV and VI.

The areas in the frontal lobe which were heavily labeled are thought to be involved in the control of somatic (areas 4 and 6) and ocular (areas 8 and 45) movements. Those in parietal cortex may be classified as areas with somatosensory functions (1, 2, PE/5, and PEa) and areas which may participate in the analysis of visual motion (Pandya and Seltzer's IPd and POa(i), which contain Maunsell and Van Essen's VIP). The parietal somatosensory areas are connected to frontal areas with somatic motor functions, while POa(i) is interconnected with the frontal eye fields (8a and 45). Both POa(i) and the frontal eye fields are known to receive inputs from visual areas specialized for motion analysis.

Cat‐301 may heavily label neurons in frontal and parietal areas that are broadly concerned with the control of somatic and ocular movements and the processing of the sensory information on which their normal execution depends.
Immunohistochemical characterization of pelvic neurons which project to the bladder, colon, or penis in rats
Authors: Keast J. R. , de Groat W. C.
Published: January 2005

Retrograde‐tracing and immunohistochemical techniques were used in combination to investigate the types of putative transmitters in pelvic neurons that project to the bladder, colon or penis of rats. In addition, populations of axon varicosities associated with these neurons were characterized.

Subpopulations of neurons in colchicine‐treated major pelvic ganglia and accessory ganglia of male rats contained immunoreactivity (IR) for tyrosine hydroxylase (TH), vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), or enkephalin (ENK), while types of immunoreactivity found in major groups of varicose axons were ENK, cholecystokinin (CCK), and somatostatin (SOM). Substance P (SP)‐IR varicose axons were much less common. Bladder and colon neurons were similar in a number of ways. Many neurons contained NPY‐IR (≥50%), fewer contained TH‐IR (25–30%), and even fewer contained ENK‐IR (5–15%) or VIP‐IR (5–10%); many neurons were associated with baskets of ENK‐IR varicosities (50–65%) and fewer neurons were surrounded by CCK‐ or SOM‐IR varicosities (30–35%). Colon neurons differed from penis neurons in having a slightly larger proportion that contained ENK‐IR (10–15%, compared with 1–3%). Penis neurons were markedly different from the other two groups in additional ways. More than 90% of them contained VIP‐IR, whereas only 5–7% contained NPY‐IR and none were immunoreactive for TH. Furthermore, although the proportion of penile neurons associated with many ENK‐IR varicosities was similar to the bladder and colon neurons (45–50%), they were rarely seen close to CCK‐ or SOM‐IR varicose axons.

These studies describe similarities and differences in the histochemical properties of neurons which project to the bladder, colon, or penis and of the varicose axons associated with those neurons. This gives further insights into the possible transmitter mechanisms involved in the regulation of different pelvic functions.
Lesions of the basal forebrain alter stimulus‐evoked metabolic activity in mouse somatosensory cortex
Authors: Ma Wu , Höhmann Christine F. , Coyle Joseph T. , Juliano Sharon L.
Published: January 2005

The role that acetylcholine plays in processing sensory stimuli is beginning to be characterized; however, morphological correlates of cholinergic effects on activity patterns in sensory cortex are not available. To study this problem, unilateral neurotoxic lesions that depleted the neocortex of acetylcholine were made in the basal forebrains of mice. The aim of these experiments was to study the effect of cholinergic depletion on stimulus‐evoked activity in the barrel field of the mouse somatosensory cortex. One month following the lesion, 2‐deoxyglucose (2DG) experiments were conducted on the lesioned and on normal mice while the animal received bilateral stimulation to the C3 whisker. The tissue was processed for acetylcholinesterase and cytochrome oxidase histochemistry and 2DG autoradiography. Evaluation of the column‐like 2DG label evoked in the somatosensory cortex revealed that the activity on the lesioned side was significantly reduced in dimension and intensity from that in the normal hemisphere. On the normal side, the activated barrels averaged 641 μm in tangential width, were 76.5% above background in density, and extended from lamina I‐V. On the lesioned side, the activated barrels were 485 μm in tangential width, 65.4% above background in density, and extended from lamina II–V. In other cortical regions, outside the stimulus‐evoked barrel field, 2DG activity values were similar on the normal and lesioned side. Additionally, both the pattern and intensity of the cytochrome oxidase staining within the barrel field displayed no differences in either hemisphere. These studies suggest that acetylcholine plays a significant role in the processing of somatosensory information. Neurotoxic lesions that diminish cortical cholinergic innervation cause a reduction of stimulus‐evoked activity levels, while underlying metabolic activity is either not affected or recovers over time.
Primate spinothalamic pathways: III. Thalamic terminations of the dorsolateral and ventral spinothalamic pathways
Authors: Apkarian A. Vania , Hodge Charles J.
Published: January 2005

The termination sites of the dorsolateral (DSTT) and ventral (VSTT) spinothalamic pathways were determined by using anterograde transport of horseradish peroxidase from the lumbar spinal cord in primates. One animal had no spinal cord lesion, while of two other animals, one received a midthoracic dorsolateral funiculus lesion, and the other received a midthoracic ventral quadrant lesion contralateral to the injection. The thalamic label in the animal with no spinal cord lesion was much less than the label in the two animals with spinal lesions. Moreover, in the animals with spinal lesions, HRP‐labeled cells were found within the thalamus. Therefore, the remaining six animals received ipsilateral hemisections and bilateral dorsal column lesions, irrespective of the contralateral lesions.

The thalamic label in the animals without contralateral lesions were assumed to represent the total spinothalamic input to the diencephalon. In these animals, label was located mainly in suprageniculate and pulvinar oralis, caudal and oral divisions of ventral posterior lateral nucleus, the lateral half of ventral posterior inferior nucleus, and zona incerta, while in the medial thalamus label was primarily in two distinct bands in medial dorsal nucleus and in the posterior dorsal protion of central lateral nucleus. Scattered lighter labeling was found in other thalamic nuclei. The pattern of terminal labeling observed in the ventral posterior lateral region was arranged in patches, while elsewhere in the thalamus a more uniform labeling pattern was observed.

The thalamic label in animals with contralateral ventral quadrant lesions represented the terminations of the DSTT, while the label in animals with contralateral dorsolateral funiculus lesions represented VSTT terminations. The labeling pattern was similar between these two groups. However, there were small differences between them. These results indicate that DSTT and VSTT terminations largely overlap and innervate the lateral and medial thalamus.
Substance P–like immunoreactivity in the lateral cervical nucleus of the owl monkey (Aotus trivirgatus): A comparison with the cat and rat
Authors: Broman Jonas , Blomqvist Anders
Published: January 2005

The location of substance P (SP) in the lateral cervical nucleus (LCN) of monkeys (Aotus trivirgatus), cats, and rats was investigated with immunohistochemical methods. Light microscopic analysis showed that SP‐positive fibers and terminals are evenly distributed throughout the LCN of the monkey and rat, whereas the SP labeling in the LCN of the cat is concentrated in the medial part of the nucleus, with only very sparse labeling in the lateral part. Electron microscopic examination of the monkey LCN revealed the presence of SP‐like immunoreactivity within terminal boutons and unmyelinated axons. The SP‐positive boutons are in synaptic contact with dendrites and, occasionally, cell bodies; they contain densely packed, clear, round synaptic vesicles, as well as dense‐core vesicles.

The distribution of SP‐like immunoreactivity in the LCN of monkeys, cats, and rats is similar to that of nociceptive‐responsive neurons demonstrated in electrophysiological experiments. The possible role of the SP‐containing fibers in the transmission of nociceptive information through the LCN is discussed.
Synaptic connections between corticogeniculate axons and interneurons in the dorsal lateral geniculate nucleus of the cat
Authors: Weber A. J. , Kalil R. E. , Behan M.
Published: January 2005

Anatomical evidence is provided for direct synaptic connections by axons from visual cortex with interneurons in lamina A of the cat's dorsal lateral geniculate nucleus. Corticogeniculate axon terminals were labeled selectively with 3H‐proline and identified by means of electron microscopic autoradiography. Interneurons in the lateral geniculate nucleus were stained with antibodies that had been raised against gamma aminobutyric acid (GABA).

We found that corticogeniculate terminals synapsed with dendrites stained positively for GABA about three times as often as with unstained dendrites. Of the corticogeniculate terminals that contacted GABA‐positive dendrites, 97% made synaptic connections with dendritic shafts. Only 3% synapsed with F profiles, the vesicle‐filled dendritic appendages characteristic of lateral geniculate interneurons. These results suggest that the corticogeniculate pathway in the cat is directed primarily at interneurons and is organized synaptically to influence the integrated output of these cells, rather than the local interactions in which their dendritic specializations participate.
Effects of convergent strabismus on the development of physiologically identified retinogeniculate axons in cats
Authors: Garraghty P. E. , Roe A. W. , Chino Y. M. , Sur M.
Published: January 2005

We have studied the effects of surgically induced convergent strabismus (esotropia) on the morphological development of retinogeniculate X and Y axon arbors in cats. Single axons were recorded in the lateral geniculate nucleus or in the optic tract adjacent to the nucleus, classified physiologically, and injected intracellularly with horseradish peroxidase. The arbors of recovered axons were compared with X and Y axon arbors from normally reared adult cats. Our data demonstrate that while X axon arbors are relatively normal, the arbors of Y axons are profoundly affected by rearing with strabismus. Y axons, whether originating from the deviated or the nondeviated eye, have substantially smaller arbors and fewer boutons in the A‐laminae of the lateral geniculate nucleus compared to Y axons in normal cats. The C‐lamina terminations of contralaterally projecting Y axons in the strabismic cats are unaffected. These results suggest that the postnatal development of retinogeniculate Y axon arbors in the A‐laminae is strongly influenced by abnormalities in postnatal visual experience. Furthermore, the present data suggest that, in addition to intraocular competitive interactions between X and Y axons previously proposed to account for the effects of other rearing conditions, interactions between afferents from the two eyes must also be involved in the development of at least Y axons.
Cytoarchitectonic organization of the spinal cord in the rat: II. The cervical and upper thoracic cord
Authors: Molander C. , Xu Q. , Rivero‐Melian C. , Grant G.
Published: January 2005

A laminar cytoarchitectonic scheme of the cervical and upper thoracic segments of the rat spinal cord is presented in which Rexed's principles for the cat are applied. The material examined in the current investigation consists of 50–80 μm‐thick unstained or Nissl‐stained sections, and 2 μm‐thick plastic‐embedded sections stained with paraphenylenediamine. The cytoarchitectonic organization was found to be basically similar to that of the cat. As in our previous study of the cytoarchitectonic organization of the lower thoracic and lumbosacral spinal cord (Molander et al.; J. Comp. Neurol. 230:133–141, '84), the borderlines between the laminae were often found to be ambiguous, suggestive of zones of transition rather than sharp borders. In addition to the laminar scheme, the distribution of certain important cell groups, including the column of Clarke, the central cervical nucleus, the lateral cervical nucleus, the lateral spinal nucleus, and the internal basilar nucleus, is described.
Cellular expression of H and B antigens in the rat olfactory system during development
Authors: Astic L. , Le Pendu J. , Mollicone R. , Saucier D. , Oriol R.
Published: January 2005

Developmental expression of H and B antigens in the rat olfactory system was studied from the embryonic day 14 up to the postnatal day 30. The H antigen was detected in the olfactory and vomeronasal epithelia as early as fetal day 14, whereas the B antigen first appeared 2 days later. The anti‐H reagent reacted strongly with sensory receptors and weakly with supporting cells in both epithelia, whereas the anti‐B reagent was specific for olfactory receptors. In the main olfactory epithelium, the H antigen was expressed from fetal day 19 by most of the receptor cells, whereas the B determinant was expressed from fetal day 16 to postnatal day 3 by only a few neuroreceptors mostly located near the epithelial surface. After the postnatal day 3, B positive neurons increased in number from the periphery toward the deeper mucosal layers and they were distributed over 3/4 of the epithelial thickness in 15‐ and 30‐day‐old rats. In the main olfactory bulb, a widespread glomerular B staining with variable binding intensity between adjacent glomeruli was already observed at birth. The vomeronasal receptor cells and their axon terminals in the accessory olfactory bulb exhibited a comparable developmental expression of the B antigen. Results suggest that the B antigen could be regarded as a marker of neuronal maturation of both the olfactory and vomeronasal receptor cells; moreover, its first appearance in the receptor cells might be temporally related to the formation of synapses between receptor axons and deutoneurons in the bulb.
Distribution and trajectory of uncrossed axons in the optic nerves of pigmented and albino rats
Authors: Jeffery Glen
Published: January 2005

Ipsilaterally projecting axons in the optic nerve of the pigmented rat are limited to a roughly retinotopic location within the intraorbital segment of the nerve. However, immediately rostral to the chiasm they are widely dispersed. Here, the way in which this change in distribution arises is analysed by tracing individual fibers retrogradely labelled from the optic tract with horseradish peroxidase (HRP). A comparison is made between albino and pigmented animals.

It is demonstrated that the change in this distribution occurs as a consequence of two types of shift in axon trajectory in the intracranial segment. Many axons change their location in the nerve gradually throughout this segment. However, in the proximal half of this region a number of axons also make abrupt changes in their trajectory by travelling at right angles across segments of the mediolateral axis of the nerve. These were seen in both the pigmented and albino animals.

Although the albino has an abnormally small ipsilateral retinofugal pathway, the distribution of ipsilateral axons in the optic nerve is very similar to that seen in pigmented animals. Consequently, it is unlikely that position in the prechiasmatic nerve is related to the chiasmatic choice made by axons in this population.
Glutamate‐positive neurons and axon terminals in cat sensory cortex: A correlative light and electron microscopic study
Authors: Conti Fiorenzo , Defelipe Javier , Farin̄as Isabel , Manzoni Tullio
Published: January 2005

Immunocytochemical methods were used to perform a correlative light and electron microscopic study of neurons and axon terminals immunoreactive to the antiglutamate (Glu) serum of Hepler et al. ('88) in the visual and somatic sensory areas of cats. At the light microscopic level, numerous Glupositive neurons were found in all layers except layer I of both cortical areas. On the basis of the dendritic staining of Glu‐positive cells, two major morphological categories were found: pyramidal cells, which were the most frequent type of immunostained neuron, and multipolar neurons, which were more numerous in layer IV of area 17 than in any other layer. A large number of Glu‐positive neurons, however, did not display dendritic labelling and were considered unidentified neurons. Counts of labelled neurons were performed in the striate cortex; approximately 40% were Glu‐positive. Numerous lightly stained punctate structures were observed in all cortical layers: the majority of these Glu‐positive puncta were in the neuropil. After resectioning the plastic sections for electron microscopy it was observed that: (1) the majority of neurons unidentifiable at light microscopic level were indeed pyramidal neurons except in layer IV of area 17, where many stained cells were probably spiny stellate neurons. Some Glu‐positive neurons, however, exhibited clear ultrastructural features of nonspiny nonpyramidal cells; (2) all synaptic contacts made by Glu‐positive axon terminals were of the asymmetric type, but not all asymmetric synaptic contacts were labelled. The vast majority of postsynaptic targets of Glu‐positive axons were unlabelled dendritic spines and shafts. The present results provide further evidence that Glu (or a closely related compound) is probably the neurotransmitter of numerous excitatory neurons in the neocortex.
Secondary vestibulocerebellar mossy fiber projection to the caudal vermis in the rabbit
Authors: Thunnissen I. E. , Epema A. H. , Gerrits N. M.
Published: January 2005

The vestibulocerebellar projection in the rabbit has been investigated by the anterograde axonal transport of tritiated leucine, wheat germ‐agglutinated horseradish peroxidase, and Phaseolus vulgaris leucoagglutinin. Mossy fiber terminals originating from all vestibular nuclei, with the exception of the lateral vestibular nucleus of Deiters, were found bilaterally in the lobules X, IX, and VIII of the caudal vermis, without a clear difference in laterality. Most of the vestibular mossy fiber terminals in the caudal vermis originated in the superior and caudal medial vestibular nuclei. Application of the different tracers led to similar results. The labeled terminals were always most numerous in the lobules X and IXd. Small to moderate numbers of mossy fiber terminals were found in the lobules IXa, b, c, and lobule VIII. The greatest change in the density of terminals occurred in most cases around the apex of lobule IXd and not in the depth of the posterolateral fissure between lobules X and IX. The mossy fiber terminals were not distributed equally over the cortex but showed a preference for the proximal parts of the individual lobules. In all experiments, the terminals exhibited a certain degree of clustering in the mediolateral direction, but the clusters were not arranged in longitudinal zones continuous over successive folia.
Sympathetic innervation of the supratentorial dura mater of the rat
Authors: Keller Jeffrey T. , Marfurt Carl F. , Dimlich Ruth V. W. , Tierney Bryon E.
Published: January 2005

The origin, density, and distribution of sympathetic nerve fibers in the supratentorial dura mater of the rat were examined in detail in the current study by using wheat germ agglutinin horseradish peroxidase (WGA‐HRP) retrograde tracing procedures, glyoxylic acid‐induced fluorescence, and dopamine beta‐hydroxylase (DBH) immunocytochemical staining of dural whole mount preparations. Application of WGA‐HRP to the superior sagittal sinus and adjacent areas of the supratentorial dura mater labeled numerous neurons in each of the left and right superior cervical ganglia. Glyoxylic acid and DBH immunocytochemical staining of fixed dural whole mount preparations revealed prominent plexuses of sympathetic nerves about the middle meningeal artery and its branches, about the superior sagittal and transverse sinuses, and „free”︁ within the dura mater, i.e., apparently unassociated with any vasculature. Significantly, in all of these areas, the density of sympathetic innervation revealed in this study was considerably greater than that previously demonstrated by other workers. An impressive population of mast cells also was observed within the dura mater of the glyoxylic acid‐treated preparations. The majority of these cells were perivascular; however, a significant number were also present within the dura unrelated to the vasculature, and occasional cells were seen in close apposition to fluorescent sympathetic nerve fibers. Taken together, the identification of a robust sympathetic plexus and prominent mast cell population associated with a dura mater that also receives significant sensory projections from the trigeminal system raises interest regarding the functional interactions of these elements. These observations warrant further consideration regarding their role in the pathogenesis of vascular headache and head pain.
Intrinsic connections and architectonics of the superior temporal sulcus in the rhesus monkey
Authors: Seltzer Benjamin , Pandya Deepak N.
Published: January 2005

The intrinsic connections of the superior temporal sulcus (STS) in the rhesus monkey were studied by anterograde and retrograde tracer techniques and correlated with a reevaluation of cortical cytoarchitecture. The polymodal region in the upper bank (area TPO) is divisible into four rostral‐to‐caudal architectonic sectors, exhibiting increasing degrees of laminar differentiation and cellularity as one proceeds caudally. These sectors, including the sulcal proisocortex (area Pro), are tied together in a sequence of reciprocal connections. Each rostrocaudal sector of area TPO also has reciprocal connections with the laterally adjacent area TAa, at the upper rim of the sulcus, and medially adjacent areas PGa and IPa, near the depth. A similar architectonic/ connectional organization exists for unimodal vision‐related cortex in the lower bank of the STS. Here a rostrocaudal sequence of reciprocal connections unites area Pro, rostral and caudal divisions of area TEa, and the extrastriate visual area OAa (MT). Area TEa also has reciprocal connections with adjacent segments of area TEm laterally, at the lower rim of the sulcus, and area IPa, medially, in the depth. In both upper and lower banks, caudal‐to‐rostral “for‐wardgoing” connections begin in supragranular layers of cortex and terminate in and around layer IV. Reciprocal, “backgoing” connections take origin from cells in infragranular layers and terminate mainly over the first layer of the caudally adjacent target zone. Orthogonally directed, “side‐to‐side” projections originate in both supra‐ and infragranular layers and terminate diffusely over all layers of cortex.
Calcitonin gene‐related peptide immunoreactivity in the visceral sensory cortex, thalamus, and related pathways in the rat
Authors: Yasui Yukihiko , Saper Clifford B. , Cechetto David F.
Published: January 2005

It has been proposed that calcitonin gene‐related peptide (CGRP) may serve as a major neuromodulator in visceral sensory pathways, but its exact role in the visceral sensory thalamus and cortex has not been determined. We therefore examined the distribution of CGRP‐like immunoreactive (CGRPir) innervation of the insular cortex and the parvicellular division of the ventroposterior nucleus of the thalamus (VPpc) in the rat by using immunohistochemistry for CGRP combined with retrograde transport of the fluorescent dye fluoro‐gold.

Modest numbers of CGRPir fibers were distributed in the dysgranular and agranular insular cortex, but few were observed in the granular insular cortex. The density of CGRPir innervation increased caudally along the rhinal fissure and was considerably greater in the perirhinal cortex. When fluorogold was injected into the insular cortex numerous retrogradely labeled neurons were seen in the VPpc, but few of these were CGRPir. Retrogradely labeled CGRPir neurons were, however, seen in the ventral lateral and medial parabrachial (PB) subnuclei. Injection of fluoro‐gold into the perirhinal cortex (which is just caudal to the insular cortex along the rhinal fissure) resulted in many retrogradely labeled CGRPir neurons in the posterior thalamic region, including the subparafascicular, the lateral subparafascicular, and the posterior intralaminar nuclei.

The VPpc was heavily innervated by CGRPir fibers but contained few CGRPir cell bodies. Injection of fluoro‐gold into the VPpc resulted in many retrogradely labeled CGRPir neurons in the external medial PB subnucleus bilaterally, but with a contralateral predominance. Smaller numbers of retrogradely labeled CGRPir neurons were also observed in the ventrolateral PB subnucleus, bilaterally with an ipsilateral predominance. These results suggest that CGRP may be a neuromodulator in the ascending visceral sensory pathways from the PB to the VPpc and the insular cortex, but not between the latter two structures.
Autoradiographic localization of thyrotropin‐releasing hormone and substance p receptors in the rat dorsal vagal complex
Authors: Manaker Scott , Rizio Gene
Published: January 2005

We utilized quantitative autoradiography to localize receptors for thyrotropin‐releasing hormone (TRH) and substance P in individual subnuclei of the rat nucleus tractus solitarii (NTS) and the dorsal vagal complex. Within the NTS, TRH receptor concentrations were highest within the gelatinosus and centralis subnuclei and the medial subnucleus rostral to the area postrema, moderate within the intermediate subnucleus and the medial subnucleus adjacent to the area postrema, and low within the ventrolateral and commissural subnuclei and the medial subnucleus caudal to the area postrema. In contrast, substance P receptor concentrations were high throughout the medial subnucleus, moderate in all other subnuclei medial to the tractus solitarius, and relatively low in subnuclei lateral to the tractus solitarius. The dorsal motor nucleus of the vagus contained high concentrations of both TRH and substance P receptors, whereas we observed low TRH and moderate substance P receptors in the area postrema. High TRH and moderate substance P receptors were observed in the adjacent hypoglossal nucleus. In addition, we compared the concentrations of TRH receptors between chloroform‐defatted and nondefatted tissue sections, and noted little effect of white matter tritium quench upon the observed TRH receptor concentrations. These results suggest that neurotransmitter receptors within the rat dorsal vagal complex are organized in a manner consistent with previous cytoarchitectural and hodological partitioning of the NTS and that the distribution of an individual neurotransmitter receptor in the NTS may correspond to the role of that transmitter in modulating autonomic function.
Immunohistochemical localization and biochemical characterization of nerve growth factor receptor in adult rat brain
Authors: Yan Qiao , Johnson Eugene M.
Published: January 2005

The expression of nerve growth factor (NGF) receptor in adult rat brain was studied by immunohistochemistry with a specific anti‐rat NGF receptor monoclonal antibody, 192‐IgG. Intense NGF receptor immunoreactivity (NGFRI) was found in structures known to be NGF responsive, including forebrain cholinergic neurons in medial septum, diagonal band of Broca, and basal nucleus of Meynert; central processes of neural‐crest‐derived sensory ganglion neurons and their innervated nucleus also contained such immunoreactivity. Distinct NGFRI staining was also found in many brain areas and cell types not known to be NGF responsive, including some hypothalamic regions, circumventricular organs, some areas related to the optic system, olfactory glomeruli, ependymal and subependymal cells in some locations, mesencephalic nucleus of the trigeminal nerve, cerebellar molecular layer, central linear nucleus, solitary tract and its nucleus, and inferior olive. The NGFRI in the circumventricular organs was further studied by in vivo labeling of 125I‐ligands. Intravenously injected 125I‐NGF, but not 125I‐cytochrome c, was specifically accumulated in the area postrema. Biochemical study of the NGF receptor showed a major band of molecular weight of approximately 90 KDa in the area postrema, choroid plexus, median eminence, and medial septum with the relative content consistent with that seen by immunohistochemistry. No evidence of a truncated NGF receptor was observed. The results of this study suggest that NGF and its receptor have broader roles in adult mammalian brain than previously thought.
Altered responses to cutaneous stimuli in the second somatosensory cortex following lesions of the postcentral gyrus in infant and juvenile macaques
Authors: Burton H. , Sathian K. , Dian‐hua Shao
Published: January 2005

Infant macaques recover tactile abilities better than older animals after somatosensory cortical lesions. To investigate the neural basis of this phenomenon, we ablated the hand representation in primary somatosensory cortex (SI) of infant and juvenile Macaca mulatta and recorded in ipsilateral second somatosensory cortex (SII) a year later. We also made tracer injections to verify the lesion boundaries and to study the connections of SII after the lesion of SI. Similar to the report of Pons et al. (Science 237:417‐420, '87), we found that substantial portions of the SII hand area were unresponsive to cutaneous stimulation of the hand in both age groups. Particularly, there were no cutaneous receptive fields restricted to the digits. Some responses were elicited in each animal by mechanical stimulation of the hand, including a proportion related to cutaneous receptive fields. This proportion was higher in the infants than in the juveniles, which may explain the greater capacity of the infants for recovery of tactile function after SI lesions. The residual somatic drive in the SII hand area of the juveniles was attributable to sparing of parts of areas 3a and 3b. However, in the infants, this explanation was not tenable since the responses noted in SII occurred even after total ablations of the postcentral gyrus. The pattern of corticocortical connections revealed by injections of HRP into the medial margin of the SI lesion and of Fast Blue into SII in one infant confirmed the absence of SI inputs to the region of SII where responses were recorded from the hand. Representations of body parts other than the hand were normally responsive, and their location was consistent with normal somatotopy in SII.
Zebrin II: A polypeptide antigen expressed selectively by purkinje cells reveals compartments in rat and fish cerebellum
Authors: Brochu Gino , Maler Leonard , Hawkes Richard
Published: January 2005

Monoclonal antibody mab‐zebrin II was generated against a crude homogenate of cerebellum and electrosensory lateral line lobe from the weakly electric fish Apteronotus leptorhynchus. On Western blots of fish cerebellar proteins, mab‐zebrin II recognizes a single polypeptide antigen of apparent molecular weight 36 kD. Immunocytochemistry of apteronotid brains reveals that zebrin II immunoreactivity is confined exclusively to Purkinje cells in the corpus cerebelli, lateral valvula cerebelli, and the eminentia granularis anterior. Other Purkinje cells, in the medial valvula cerebelli and eminentia granularis posterior, are not zebrin II immunoreactive. Immunoreactive Purkinje cells are stained completely, including dendrites, axons, and somata. The antigen seems to be absent only from the nucleus. A similar distribution is seen in catfish, goldfish, and a mormyrid fish. Zebrin II immunoreactivity is also found in the rat cerebellum. Western blotting of rat cerebellar proteins reveals a single immunoreactive polypeptide, with apparent, molecular weight 36 kD, as in the fish. Also as in the fish, staining in the adult rat cerebellum is confined to a subset of Purkinje cells. Peroxidase reaction product is deposited throughout the immunoreactive Purkinje cells with the exception of the nucleus. No other cells in the cerebellum express zebrin II. At higher antibody concentrations, a weak glial cross reactivity is seen in most other brain regions: we believe that this is probably nonspecific. Zebrin II+ Purkinje cells are clustered together to form roughly parasagittal bands interposed by similar non‐immunoreactive clusters. In all there are 7 zebrin II+ and 7 zebrin II− compartments in each hemicerebellum. One immunoreactive band is adjacent to the midline; two others are disposed laterally to each side in the vermis; there is a paravermal band; and finally three more bands are identified in each hemisphere. Both in number and position, these compartments correspond precisely to the bands revealed by using another antibody, mabQ113 (anti‐zebrin I). In both fish and rat the compartmentation revealed by zebrin II immunocytochemistry is related to the organization of cerebellar afferent and efferent projections and may provide clues as to the fundamental architecture of the vertebrate cerebellum.