bluuebunny/crossref_metadata_2025 huggingface dataset:
Patterns of glutamate decarboxylase immunostaining in the feline cochlear nuclear complex studied with silver enhancement and electron microscopy
Authors: Adams Joe C. , Mugnaini Enrico
Published: January 2005

The cochlear nuclear complex of the cat was immunostained with an antiserum to glutamate decarboxylase (GAD), the biosynthetic enzyme for the inhibitory neurotransmitter GABA, and studied with different procedures, including silver intensification, topical colchicine injections, semithin sections, und immunoelectron microscopy. Immunostaining was found in all portions of the nucleus. Relatively few immunostained cell bodies were observed: most of those were in the dorsal cochlear nucleus and included stellate cells, cartwheel cells, Golgi cells, and unidentified cells in the deep layers. An accumulation of immunoreactive cells was also found within the small cell cap and along the medial border of the ventral cochlear nucleus. Immunostained cells were sparse in magnocellular portions of the ventral nucleus. Most staining within the nucleus was of nerve terminals. These included small boutons that were prominent in the neuropil of the dorsal cochlear nucleus, the granule cell domain, in a region beneath the superfi‐cial granule cell layer within the small cell cap region, and along the medial border of the ventral nucleus. Octopus cells showed small, GAD‐positive terminals distributed at moderate density on both cell bodies and dendrites. Larger, more distinctive terminals were identified on the large cells in the ventral nucleus, in particular on spherical cells and globular cells. There was a striking positive correlation of the size, location, and complexity of GAD‐positive terminals with the size, location, and complexity of primary fiber endings on the same cells. This correlation did not hold in the dorsal nucleus, where pyramidal cells receive many large GAD‐positive somatic terminals despite the paucity of primary endings on their cell bodies. The GAD‐positive terminals contained pleomorphic synaptic vesicles and formed symmetric synaptic junctions that occupied a substantial portion of the appositional surface to cell bodies, dendrites, axon hillocks, and the begin‐ning portion of the initial axon segments. Thus, the cells provided with large terminals can be subjected to considerable inhibition that may be activated indirectly through primary fibers and interneurons or by descending inputs from the auditory brainstem.
Glycine: An alternative transmitter candidate of the pallidosubthalamic projection neurons in the rat
Authors: Takada M. , Hattori T.
Published: January 2005

Autoradiographic retrograde tracing techniques with radioactive transmitters were used to analyse the identity of a putative transmitter in the rat pallidosubthalamic (GP‐STN) pathway. One to 2 hours after the stereotaxic injection of 3H‐glycine restricted to the STN, a large number of neuronal somata were radiolabeled in the GP. No comparable labeling was observed following the injection of 3H‐γ‐aminobutyric acid (3H‐GABA) into the same nucleus even with survival times as long as 6 hours. Specifically, no significant somatic labeling was detected either in the GP or in the caudoputamen (CPU). Only when 3H‐GABA was injected into the substantia nigra did CPU and GP neurons become labeled. On the contrary, STN neuronal somata were invariably labeled 6 hours after the intrapallidal injection of 3H‐GABA, whereas no perikaryal labeling was observed in the STN after 3H‐glycine injection into the GP. The perikaryal labeling was prevented in all cases by intraventricular administration of colchicine 1 day before the isotope injections. The observations suggest that 3H‐glycine was preferentially transported retrogradely through the GP‐STN pathway, and 3H‐GABA through the STN‐GP projection. In view of the recent controversy on the role of GABA as a putative transmitter of the GP‐STN projection, we now propose glycine as an alternative transmitter candidate of these critically situated neurons in the basal ganglia.
Abrupt loss of dependence of retinopetal neurons on their target cells, as shown by intraocular injections of kainate in chick embryos
Authors: Catsicas Stefano , Clarke Peter G. H.
Published: January 2005

We have examined the capacity of neurons in the chick isthmo‐optic nucleus (ION) to survive when their target neurons in the contralateral retinal are destroyed by intraocular injections of kainate (KA) at different stages in development.

The retinal vulnerability to KA builds up progressively from embryonic day 10 (E10) until a plateau is reached at E15 (see accompanying paper); and the effects on the ION increase in parallel, almost all the ION neurons being rapidly lost after the E15 injections. KA injection before E15 lesioned only part of the retina and caused degeneration only in the topographically corresponding region of the ION.

Near the end of the natural cell death period in the ION (E17), this initial dependence on the target cells is rapidly lost. Already at E16 the injections kill less ION neurons, and by E19 they kill none of them. The ION neurons have become completely insensitive to the KA injections and appear normal more than 4 months later, although axotomy (by eye removal) at a similar age would by then have killed them. The ectopic ION neurons, scattered outside the ION but projecting to the retina, are never affected by KA injections at any age.
Organization of vasotocin‐immunoreactive cells and fibers in the canary brain
Authors: Kiss J. Z. , Voorhuis T. A. M. , van Eekelen J. A. M. , de Kloet E. R. , de Wied D.
Published: January 2005

The distribution of vasotocin (VT)‐immunoreactive neuronal perikarya and fibers in the canary (Serinus canaria) was investigated with immunohistological techniques. The results suggest that most VT‐stained cell bodies are located in three diencephalic regions. First, a large number of densely packed neurons are found in the paraventricular nucleus (PVN) and the anterior preoptic nucleus. Neurons here vary widely in size and shape. Small‐size rounded neurons and large‐size multipolar neurons appear to concentrate in separate subdivisions. Second, a series of loosely organized cell groups of medium‐ to large‐size cells occurs in the lateral parts of the hypothalamus. Those aggregates of neurons apparently correspond to subdivisions of the supraoptic nucleus (SON). Third, diffusely distributed, lightly stained cells are found dorsal to the paraventricular nucleus in the dorsal diencephalons. A number of cells of this group seem to be located in the basal septal area and bed nucleus of the stria terminalis. Immunoreactive fibers and varicosities concentrate in brain regions that are associated with neuroendocrine, autonomic, and limbic functions. Axons from the PVN and SON form compact bundles of the hypothalamohypophysial tract in the lateral hypothalamus and then funnel into the internal zone of the medium eminence (ME). Furthermore, a heavy innervation seems to be present in the pulisadal, external zone of the ME. A substantial number of fibers appear to leave the PVN toward extrahypothalamic areas. Most extrahypothalamic VT fibers innervate telencephalic and brainstem regions that are thought to be involved in mediation of limbic and autonomic functions. These areas include the lateral and medial septum, the lateral habenula, the subtantia grisea centralis, the area ventralis (Tsai), the locus coeruleus, raphe nuclei, the nucleus tractus solitarii, and lateral medulla. In addition, fibers with immunoreactivity for VT innervate structures such as the optic tectum and the nucleus ovoidalis that have been implicated in sensory processing of visual and auditory information. Finally, VT fibers and varicosities occur in centers including the nucleus robustus archistriatalis and nucleus intercollicularis that have been implicated in vocal control.
Cell death in the developing retinal ganglion cell layer of the wallaby Setonix brachyurus
Authors: Dunlop S. A. , Beazley L. D.
Published: January 2005

The distribution and number of dying cells in the developing retinal ganglion cell layer of the wallaby Setonix brachyurus were assessed by using cresyl violet stained tissue. The density of dying cells has been expressed per 100 live cells for the entire retinal surface, data being presented as a grid of 500 μm squares. For statistical analysis, retinae were divided into 8 regions; dorsal, ventral, nasal, and temporal quadrants, each further divided into center and periphery. This method allowed comparison of the extent of cell death at different retinal locations as the high density area centralis of live cells developed temporal to the optic disk from 60 days onward.

Between 30 and 70 days, dying cells were seen across the entire retina; beyond 100 days very few were seen. Initially, there was a significantly higher incidence of dying cells in the central retina compared to the periphery, whereas from 50 days this situation was reversed. Analysis of the central retina before and during area centralis formation consistently indicated a significantly lower number of dying cells per 100 live cells in temporal compared to other retinal quadrants. This differential pattern suggests that cell death lowers live cell densities less in the emerging area centralis than elsewhere, and therefore must play a part in establishing live cell density gradients. However, we cannot exclude the possibility that other factors are also instrumental. Indeed, factors such as areal growth (Beazley et al., in press) presumably operate at later stages since live cell density gradients continue to be accentuated even after cell death is complete.

Numbers of dying cells peaked by 50 days, reaching approximately 1% of the live cell population. At this stage, counts were also maximal for live cells with values up to 30% above the adult range.
Effects of prenatal irradiation on the development of cerebral cortex and corpus callosum of the mouse
Authors: Schmidt Sergio L. , Lent Roberto
Published: January 2005

Defects of the cerebral cortex and corpus callosum of mice subjected prenatally to gamma irradiation were evaluated as a function of dose and of embryonic age at irradiation. Pregnant mice were exposed to a gamma source at 16, 17, and 19 days of gestation (E16, E17, and E19, respectively), with total doses of 2 Gy and 3 Gy, in order to produce brain defects on their progeny. At 60 postnatal days, the brains of the offspring were analyzed qualitatively and quantitatively and compared with those of nonirradiated animals. Mice irradiated at E16 were all acallosal. Those that were exposed to 2 Gy displayed an aberrant longitudinal bundle typical of other acallosals, but this was not the case in those irradiated with 3 Gy. The corpus callosum of animals irradiated at E17 with 3 Gy was pronouncedly hypotrophic, but milder effects were observed in the other groups. Quantitative analysis confirmed a dependence of callosal midsagittal area upon dose and age at irradiation, and, in addition, indicated an interaction between these variables. The neocortex of irradiated animals was hypotrophic: layers II‐III were much more affected than layer V, and this was more affected than layer VI. Quantitative analysis indicated that this effect also depended on dose and age at irradiation and that it was due to a loss of cortical neurons. Furthermore, a positive correlation was found between the number of neurons within layers II‐III, and V and the midsagittal area of the corpus callosum. Ectopic neurons were found in the white matter and in layer I of animals irradiated at E16 and E17, indicating that fetal exposure to ionizing radiation interfered with the migration of cortical neuroblasts.
Immunocytochemical studies of vasotocin, mesotocin, and neurophysins in the Xenopus hypothalamo‐neurohypophysial system
Authors: Conway Kevin M. , Gainer Harold
Published: January 2005

Mesotocinergic and vasotocinergic neurons, which constitute the principal neurons in the hypothalamo‐neurohypophysial system in Xenopus, were studied by immunocytochemical techniques. Antibodies that could unequivocally distinguish mesotocin, vasotocin, and their respective neurophysins were used in these studies. A monoclonal antibody directed at rat oxytocin‐associated neurophysin (PS‐36) detected an antigen that was colocalized with vasotocin, whereas a monoclonal antibody to rat vasopressin‐associated neurophysin, (PS‐45) crossreacted with an antigen in mesotocinergic cells. As vasotocin is regarded as an evolutionary precursor of vasopressin, and as mesotocin is usually associated with oxytocin, we were surprised to see this apparent epitope switch in the associated neurophysins. One interpretation of this epitope switch is that the final exons encoding for the carboxy‐terminals of the mammalian neurophysins, which contain the PS‐45 and PS‐36 antibody epitopes, are in reversed positions in Xenopus. Approximately 4,000 mesotocinergic and vasotocinergic neurons and their fibers were topographically mapped in the Xenopus hypothalamus. The two types of neurons were intermingled and scattered throughout a large contiguous region including but not limited to the preoptic recess. Small, medium size, and large cells contained these antigens. Immunoreactive fibers were seen in the preoptic area, the neurohypophysial tract, the median eminence, and the neural lobe of the pituitary. The neurophysin‐specific monoclonal antibodies have several advantages as phenotypic markers in development; i.e., high titer, low background, and affinity for the prohormone forms as well as for the fully processed neurophysin polypeptides. Their antigens are related gene products whose expression is central to the identity of the two cell types and whose expression is differentially controlled in development. This characterization of their adult distribution provides a basis for future studies of the development of peptidergic phenotype in the central nervous system of Xenopus.
Organisation of subcortical pathways for sensory projections to the limbic cortex. I. Subcortical projections to the medial limbic cortex in the rat
Authors: Thompson Scott M. , Robertson Richard T.
Published: January 2005

Subcortical afferent projections to the medial limbic cortex were examined in the rat by the use of retrograde axonal transport of horseradish peroxidase. Small iontophoretic injections of horseradish peroxidase were placed at various locations within the dorsal and ventral cingulate areas, the dorsal agranular and ventral granular divisions of the retrosplenial cortex and the presubiculum. Somata of afferent neurons in the thalamus and basal forebrain were identified by retrograde labeling.

Each of the anterior thalamic nuclei was found to project to several limbic cortical areas, although not with equal density. The anterior dorsal nucleus projects primarily to the presubiculum and ventral retrosplenial cortex; the anterior ventral nucleus projects to the retrosplenial cortex and the presubiculum with apparently similar densities; and the anterior medial nucleus projects primarily to the cingulate areas.

The projections from the lateral dorsal nucleus to these limbic cortical areas are organized in a loose topographic fashion. The projection to the presubiculum originates in the most dorsal portion of the lateral dorsal nucleus. The projection to the ventral retrosplenial cortex originates in rostral and medial portions of the nucleus, whereas afferents to the dorsal retrosplenial cortex originate in caudal portions of the lateral dorsal nucleus. The projection to the cingulate originates in the ventral portion of the lateral dorsal nucleus.

Other projections from the thalamus originate in the intralaminar and midline nuclei, including the central lateral, central dorsal, central medial, paracentral, reuniens, and paraventricular nuclei, and the ventral medial and ventral anterior nuclei. In addition, projections to the medial limbic cortex from the basal forebrain originate in cells of the nucleus of the diagonal band. Projections to the presubiculum also originate in the medial septum.

These results are discussed in regard to convergence of sensory and nonsensory information projecting to the limbic cortex and the types of visual and other sensory information that may be relayed to the limbic cortex by these projections.
Afferent and efferent connections of the oculomotor cerebellar vermis in the macaque monkey
Authors: Yamada Jinzo , Noda Hiroharu
Published: January 2005

Saccadic eye movements were evoked with weak currents applied to a circumscribed vermal area. The area was confined to lobule VII in the majority of the monkeys and coincided with the distribution of saccade‐related neural activity. We defined this area as the oculomotor vermis and studied its anatomical connections with wheat germ‐agglutinin conjugated horseradish peroxidase (WGA/HRP) and HRP.

When injected HRP was confined to the oculomotor vermis, most labeled Purkinje axons terminated ipsilaterally in an ellipsoidal region in the mediocaudal aspect of the fastigial nucleus. Retrogradely labeled cells were found in two relatively circumscribed regions in the fastigial nucleus: one group was in the lateral half of the ellipsoidal terminal region and the other group was in a spherical region near the lateral margin of the nucleus.

Following the injection of HRP into the oculomotor vermis, the largest population of retrogradely labeled neurons was found in the nucleus reticularis tegmenti pontis. Labeled cells were located only in the medial and dorsolateral portions of the nucleus. The cell aggregates in the dorsolateral portion merged with densely labeled cells of the processus tegmentosus lateralis. The second largest population of labeled cells was found in the pontine nuclei. Approximately 28% of the labeled pontine cells aggregated in the paramedian pontine nucleus, whereas the other labeled pontine cells were widely distributed in the dorsal part of the pontine peduncular nucleus and the dorsolateral pontine nucleus. Labeled cells were scattered also in the pontine raphe, the paramedian pontine reticular formation, and the interfascicular nucleus at the rostral level of the hypoglossal nucleus. Fewer labeled cells were discovered in the vestibular nuclear complex and the prepositus hypoglossi. In the inferior olivary nucleus, labeled cells were located in the subnucleus b of the medial accessory nucleus.
Parasagittal organization of the rat cerebellar cortex: Direct correlation between antigenic purkinje cell bands revealed by mabQ113 and the organization of the olivocerebellar projection
Authors: Gravel Claude , Eisenman Leonard M. , Sasseville Rachel , Hawkes Richard
Published: January 2005

The Purkinje cells of the cerebellar cortex and the cortical afferent and efferent projections are organized into parallel parasagittal zones. The parasagittal organization is clearly revealed by immunocytochemistry with a monoclonal antibody, mabQ113. The mabQ113 antigen is confined to a subset of Purkinje cells that are clustered together to form an elaborate, highly reproducible pattern of bands and patches, interspersed with similar mab‐Q113– regions. The mabQ113 + territories have been classified into seven parasagittal bands (P1 + ‐P7 +) in each hemicerebellum. The degree of correspondence between the compartments revealed by the anterograde labeling of the olivocerebellar projection and by mabQ113 immunocytochemistry has been explored in the adult rat. Horseradish peroxide‐wheat germ agglutinin conjugate was injected as an anterograde tracer into the inferior olivary complex. When the injection site did not encompass all the olive, an incomplete, patchy labeling of the molecular layer was seen in the cerebellar cortex. Labeled zones of the molecular layer were interrupted by unlabeled regions to give a pattern of parasagittal cortical bands. The positions of these bands were compared with the distribution of the mabQ113 + antigenic bands as seen on the two adjacent sections. Labeled climbing fibers were found to terminate on both mabQ113 + and mabQ113 ‐ Purkinje cell zones. The mabQ113 +/mabQ113‐ boundaries and the bands of climbing fibers seen by using the anterograde tracer typically coincide. The one consistent exception is the midline band of mabQ113 + Purkinje cells, P1 +.

The normal olivocerebellar projection is exclusively contralateral and the climbing fiber projection to the paramedian vermis splits P1 + down the middle, implying that it consists of two adjacent mabQ113+ bands not separated by mabQ113‐territory. It is likely that the climbing fiber projection to the cerebellar cortex and the distribution of the two Purkinje cell phenotypes share a common compartmental organization.
Influence of nerve growth factor on chick trigeminal motor nucleus explants
Authors: Heaton Marieta Barrow
Published: January 2005

Explants of the metencephalic basal plate from stage 11 (40–hour) chick embryos containing the trigeminal (V) motor nucleus were cultured in standard control medium, in medium supplemented with nerve growth factor (NGF), in medium supplemented with NGF and specific antibodies to NGF (anti‐NGF), and in medium supplemented with anti‐NGF alone. The explants grown in the presence of NGF displayed an enhanced density and complexity of neuritic outgrowth, with this growth significantly surpassing that seen in the control group (p≥.001). The explants grown in NGF plus anti‐NGF and those grown in anti‐NGF alone did not differ from controls. The results indicate that this early cholinergic population is specifically responsive to NGF. This finding is consistent with recent studies in which NGF receptor binding has been found in this and other early brainstem and spinal cord motor neuron populations. The possible relevance of these observations to the normal sequence involved in the development of the V motor nucleus is discussed, particularly as they may relate to the relationship between the V ganglion and the developing V motor population.
Deafferentation‐induced alterations in the rat dorsal horn: II. Effects of selective poisoning by pronase of the central processes of a peripheral nerve
Authors: LaMotte Carole C. , Kapadia Shanta E.
Published: January 2005

Studies of deafferentation and regeneration, as well as studies requiring several tracing techniques, would benefit from availability of a substance that would selectively lesion the central components of a single peripheral nerve. Pronase, a combination of proteolytic enzymes, was tested for this purpose.

Three weeks following microinjection of Pronase (5–25 mg) into the rat sciatic nerve, many ganglia cells in the L3‐L5 ganglia were degenerated. Degeneration of primary afferents also was evident in the dorsal horn, as detected by silver Fink‐Heimer methods. Patterns of terminal fields coincided with those mapped in normal rats for the sciatic nerve by using HRP transport.

Ultrastructural changes were similar to those seen at 3 weeks following sciatic nerve section or rhizotomy, as described in our companion paper. However, degenerative changes following Pronase injection of the sciatic nerve were quantitatively greater than those following sciatic nerve section alone. Degenerating terminals were either electron lucent and swollen, electron dense, or filamentous with loss of vesicles. Postsynaptic dendrites, and occasionally somata, also showed signs of degeneration. Some became electron dense, others accumulated osmiophilic floccular material, but most became electron lucent and developed large membrane‐bound cavities. Glial processes expanded around degenerating elements, wrapping around both terminals and dendrites. Glial sheets covered denervated dendritic and somatic spines, separating them from their terminals. Labyrinth formations of glial sheaths around debris were also found. Pronase appears to mimic the effects of mechanical destruction of primary afferents, but when compared to rhizotomy, is selective for the afferents of a single nerve, and, when compared to nerve section, produces a greater effect. Further, the substance is relatively safe for investigators compared to other toxins such as ricin.
Structure‐function relationships in the rat brainstem subnucleus interpolaris: II. Low and high threshold trigeminal primary afferents
Authors: Jacquin Mark F. , Stennett Richard A. , Renehan William E. , Rhoades Robert W.
Published: January 2005

Prior studies indicate that vibrissa, guard hair, hairy skin, mucosa, and nociceptive trigeminal primary afferents give rise to morphologically distinct terminal arbors in the medullary dorsal horn. The present study describes the extent to which similar structure‐function relationships exist in the rostrally adjacent subnucleus interpolaris (SpVi). Seventy‐three axons were physiologically characterized and visualized by standard intra‐axonal HRP labeling techniques. They responded to guard hair (GH) or vibrissa (VIB) deflection; gentle pressure applied to hairy skin (HS), glabrous skin (GS), lingual mucosa (LM), or an incisor (PER); or a noxious pinch of the face (NOX). Response latencies to trigeminal ganglion shocks were equivalent for all categories with low threshold receptive fields (mean = 0.44 ms), and these were significantly shorter than those of fibers with high threshold NOX receptive fields (mean = 0.88 ms). All axons gave off transversely oriented collaterals into SpVi with rostrocaudal discontinuities in their arbors. Collaterals were topographically organized. Axons innervating the rostral mouth and face terminated medially, and those that supplied the caudal face innervated successively more lateral SpVi. The dorsal face was represented in the ventral SpVi, whereas the ventral face and mouth were represented more dorsally. This transverse topography extended largely throughout the rostrocaudal extent of SpVi.

VIB, GH, GS, and LM collaterals had similar configurations with circumscribed arbors. HS, PER, and NOX arbors had a “stringy” shape without a clear terminal focus, save for the fact that PER and NOX collaterals often terminated in rostrally displaced substantia gelatinosa at the level of the caudal SpVi. Analysis of variance, considering only those data from mystacial VIB, GH, and HS fibers, indicated significant differences for all of the following measures: number of collaterals, number of boutons per collateral, arbor area, arbor circumference, and arbor circularity (form factor). A similar analysis, considering all fiber types, indicated significant differences for only the following measures: number of collaterals, arbor area, and arbor circumference. Individual group comparisons between the more heavily sampled functional categories indicated that GH afferents had significantly.
Topographic and zonal organization of the olivocerebellar projection in the reeler mutant mouse
Authors: Blatt Gene J. , Eisenman Leonard M.
Published: January 2005

The organization of the olivocerebellar projection in the homozygous reeler mouse (rl/rl) was studied with the use of microinjections of 3H‐leucine in different regions of the inferior olivary complex (IO) or horseradish peroxidase conjugated with wheat germ agglutinin (WGA‐HRP) into medial, intermediate, or lateral regions of the reeler cerebellum. The purpose of this investigation was to determine the pattern of termination of olivocerebellar climbing fibers (CFs) in the cerebellum via an anterograde tracing technique, and to determine the topographic organization of the olivocerebellar projection via both anterograde and retrograde methods. The inferior olive injections were made via the ventral (i.e., retropharygeal) approach to the IO to minimize diffusion into other brainstem precerebellar nuclei and thus to ensure accurate well‐restricted, injection sites. Labeled CF terminals were seen in both the superficial Purkinje cell (PC) layer (normally positioned PCs) and around PCs in the granular layer and central masses (ectopic PCs). The pattern of labeling is suggestive of orthogonal organization, in that vertical columns of cells are labeled. This is especially apparent in the medial PC group, where at least three bands are identified. Within an orthogonal band, CF terminals are seen around both superficial and deep Purkinje cells. Our data indicate that olivocerebellar topography is generally similar in reeler and normal mice despite severe abnormalities in target cell position in the reeler. The medial cerebellar region receives input from the caudal two‐fifths of the medial accessory olive (MAO). The intermediate PC cluster receives input from more rostral portions of all three olivary divisions (MAO), principal olive [PO] and dorsal accessory olive [DAO], while rostral portions of MAO and PO project to the lateral cerebellum. These results indicate that the zonal organization of the olivocerebellar projection in the adult reeler exhibits a pattern generally similar to that seen in normal mice. This suggests that an afferent system can develop a normal organization despite having ectopic targets.
Visual system of the channel catfish (Ictalurus punctatus): III. Fiber order in the optic nerve and optic tract
Authors: Dunn‐Meynell A. A. , Sharma S. C.
Published: January 2005

In channel catfish the ganglion cell axons leave the retina via a ring of approximately 13 separate optic papillae. Each papilla serves an area of retina extending from the central zone of the retina to the periphery. Papillae located at a dorsal position in the ring serve exclusively dorsal retina. Ventrally located papillae, however, have an exaggerated peripheral retinal representation, so that they serve mostly ventral retina but also some areas of peripheral retina dorsal to the nasal and temporal poles. The ganglion cell axon bundles departing from the retina via individual papillae were labelled with horseradish peroxidase, and sections of the optic pathway were examined to reveal the topographic organization of the fibers. The topographic order of the optic nerve was dissimilar to that of cichlids and goldfish. Fibers from individual papillae remained together throughout the optic nerve. Close to the optic nerve head, the papillae were arranged as a continuum around the U‐shaped optic nerve, without the discontinuity in the representation of the ventral retina seen in other fish. Fibers associated with the dorsal papillae were located at the tip of the caudolateral arm of the U, and fibers from ventral papillae were on the rostromedial arm. Fibers from nasally and temporally located papillae were found on the base of the U. By the level of the optic chiasm the U shape had flattened out but retained the relative ordering of the papillae. Rotation of the nerve as it became the optic tract brought the representation of the ventral papillae to the dorsal pole of the tract, and the dorsal papillae to the ventral tract. It was only in the optic tract that rearrangement of fibers became apparent. As described above, the axons of some ganglion cells in dorsal, peripheral retina left the retina and travelled through the optic nerve with axons from extreme ventral retina. In the optic tract, these dorsal fibers joined the main body of fibers from the dorsal retina. The significance of these observations for theories of fiber rearrangement is discussed.
Development of chorda tympani nerve taste responses in the hamster
Authors: Hill David L.
Published: January 2005

To determine whether changes in salt and sugar responses occur during development in the hamster, multifiber responses were recorded from the chorda tympani nerve while stimulating the anterior tongue of preweanling, early postweanling, and adult hamsters. Gustatory stimuli included 0.1 and 0.5 M solutions of NH4Cl, NaCl, LiCl, and KCl, and concentration series (0.01–1.0 M) of glucose, fructose, sucrose, maltose, lactose, and (0.0005–0.01 M) saccharin.

Dramatic alterations in hamster peripheral gustatory sensitivities occurred with age, with the direction and magnitude of change dependent on the specific stimulus. Response magnitudes to 0.1 M solutions of NaCl and LiCl decreased with age compared to the NH4Cl response, whereas responses to all other salt stimuli remained constant during development. Responses to all sugars and saccharin compared to the NH4Cl response increased during development across a large concentration range; however, the age at which mature responses were achieved depended on the specific “sweet” stimulus.

Whereas these findings demonstrate that the hamster peripheral gustatory system is dynamic during postnatal development, the hamster has a unique developmental pattern of salt taste development compared to other species. Specifically, the effectiveness of NaCl and LiCl decrease during development compared to NH4Cl in the hamster, but increase dramatically in the rat and sheep. Thus, the developmental patterns are opposite in direction for the hamster compared to the rat and sheep and may relate to the environmental pressures imposed upon each species.
Comparative topography of projections from the mesodiencephalic junction to the inferior olive, vestibular nuclei, and upper cervical cord in the cat
Authors: Spence Sandra J. , Saint‐Cyr Jean A.
Published: January 2005

Distributions of neurons located in the central rostral mesencephalon and caudal diencephalon that project to the upper cervical spinal cord, vestibular nuclei, or inferior olive were studied in the cat by using retrograde axonal transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP). Afferent sources to all of these targets were observed in the interstitial nucleus of Cajal (INC), the region surrounding the fasciculus retroflexus (PF), and the nucleus of the fields of Forel (NFF). Three‐dimensional reconstruction revealed differences in densities of cells projecting from these common areas. Spinal projecting cells were present in slightly greater numbers in the caudal two‐thirds of the INC, whereas those projecting to the vestibular complex were more numerous in the rostral two‐thirds of this nucleus. A relatively smaller number of olivary projecting cells were dispersed throughout the INC. Olivary afferent sources outnumber those with spinally directed or vestibularly directed axons in the PF region. In the fields of Forel, cells projecting to the vestibular nuclei or inferior olive were concentrated medially, whereas cells projecting to the spinal cord appeared both medially and laterally. Each type of afferent source was also seen in the nucleus of the posterior commissure and the posterior ventral lateral hypothalamic area. Unique sources of afferents to the inferior olive were observed in the parvicellular red nucleus (ipsilateral to the injections) and the anterior and posterior pretectal nuclei. A large number of labeled neurons was seen in the nucleus of Darkschewitsch after injections of tracer into the inferior olive, but this projection did not appear to be unique, as small numbers of labeled cells were also seen after injections into the cervical spinal cord. The Edinger‐Westphal nucleus and the adjacent somatic oculomotor nucleus contained cells which projected separately to the spinal cord or the vestibular complex, and the superior colliculus contained cells which projected separately to the contralateral spinal cord or the contralateral inferior olive. In this study, it was also noted that neurons in the medial terminal nucleus of the accessory optic tract projected to the ipsilateral inferior olive or to the contralateral vestibular complex. These differences in locations and densities of cells projecting to the cervical spinal cord, vestibular complex, and inferior olive may underlie functional specializations in these areas in relation to vertical eye and head movement control and to neural systems controlling postural adjustments accompanying limb movements.
Auditory brainstem of the ferret: Sources of projections to the inferior colliculus
Authors: Moore David R.
Published: January 2005

The organization of the auditory brainstem in adult, darkly pigmented ferrets was studied by using the retrograde transport of the lectin wheat germ agglutinin–horseradish peroxidase injected into one inferior colliculus. Retrogradely labelled neurons were found bilaterally in every nucleus of the auditory brainstem. The greatest number of labelled neurons was found in the cochlear nuclei contralateral to the injection site, the ipsilateral medial superior olivary nucleus, both lateral superior olivary nuclei, the ipsilateral ventral nucleus of the lateral lemniscus, both dorsal nuclei of the lateral lemniscus, and the contralateral inferior colliculus. Quantitative assessment of the projections from the cochlear nuclei showed that the number of contralaterally projecting neurons exceeded the number of ipsilaterally projecting neurons by about 50 to one. This ratio remained relatively stable over a wide range of volumes of injected lectin, whereas the absolute number of labelled neurons on each side varied by at least twofold for a constant volume of lectin. These results provide basic data on the ferret auditory system and demonstrate quantitatively some properties of the projections between the cochlear nucleus and the inferior colliculus.
Unilateral odor deprivation: Early postnatal changes in olfactory bulb cell density and number
Authors: Frazier Lauren L. , Brunjes Peter C.
Published: January 2005

Surgical closure of an external naris of the rat from postnatal day 1 to day 30 results in a 25% decrease in the size of the ipsilateral olfactory bulb. Decreases in size must result from changes in either the number of neurons and/or glia, or their size or both. The present study was designed to quantify cell density (Nv) and number at various early postnatal ages in order to examine both normal patterns of maturation and sequences of change resulting from deprivation.

Data from control subjects indicated that numbers of mitral cells remained constant while numbers of external tufted cells increased. Both relay cell populations exhibited increases in nuclear size suggestive of substantial postnatal differentiation. All interneuronal and glial populations increased in number, although differences in maturational patterns were observed between cell species. For example, light and dark subpopulations of granule cells differed in the timing of peak cellular density, and an inside‐to‐outside gradient of maturation was found for dark granule cells.

Growth curves were generally similar in occluded and control pups until approximately day 20, when deprivation resulted in decreased number and nuclear area of external tufted cells and density and number of granule cells and their associated glia. Light granule cells were affected earlier than dark cells, perhaps because of their earlier arrival in the granule cell layer. The affected cell groups represent the last relay and interneuronal populations to be generated, perhaps explaining their particular susceptibility to the effects of experience. Most of the changes emerged late, thus suggesting that they represent the culmination of a series of experience‐induced changes within the maturing bulb. The observed effects may result from either altered cellular proliferation or death patterns (or both), alternatives now under investigation.
Atlas of serotonin‐containing neurons in the optic lobes and brain of the crayfish, Cherax destructor
Authors: Sandeman D. C. , Sandeman R. E. , Aitken A. R.
Published: January 2005

An atlas of neurons in the brain of the crayfish Cherax destructor that are immunoreactive to antibodies raised against serotonin has been compiled from whole mount preparations. Neuronal networks of serotonin‐containing cells are identified in the optic lobes and protocerebrum, in the deutocerebrum, and in the tritocerebrum. The consistency of the whole‐mount technique allows 50 out of a total of about 100 immunoreactive cells to be individually identified according to their neuronal architecture or the location of their cell somata or axons. Apart from six neurons with axons in the oesophageal connectives, all the immunoreactive cells are intrinsic to the optic lobes and brain.
Anatomy of macaque fovea and spatial densities of neurons in foveal representation
Authors: Schein Stanley J.
Published: January 2005

Fine visual sampling in the macaque depends on the high density of cone outer and inner segments in the fovea. Cone pedicles, at the opposite, presynaptic end of the cone, are absent from the center of the fovea. Both ends of the cones, inner segments and pedicles, are closely packed within their respective monolayers, but the spatial density of foveal pedicles is lower because foveal pedicles are wider than inner segments. Because there is one pedicle for every inner segment, and because pedicles are wider than inner segments, increase in eccentricity finds increasing lateral displacement of the cone's pedicle from its inner segment. Further increase of eccentricity finds inner segment density falling below pedicle density, and so this lateral displacement declines. By 2–3 mm from the center, inner segments catch up with pedicles. Additional lateral displacements, of bipolar cells from pedicles and ganglion from bipolar cells, are largest for central‐most elements and fall steeply with eccentricity.

By taking into account all of these lateral displacements, the eccentricity of the cone inner segment(s) associated with a ganglion cell was determined, as was the area of inner segments represented by a unit area in the ganglion cell layer. Then raw ganglion cell densities were transformed to densities comparable to densities of inner segments and of cells in dorsal lateral geniculate nucleus. On average there appears to be close to 2 ganglion cells for each cone in the central fovea out to about 2.5°. Thus, the density of foveal ganglion cells is sufficient to allow each red and each green cone to connect to 2 midget ganglion cells, and each blue cone to connect to 1 ganglion cell. Furthermore, there appears to be a single dorsal lateral geniculate cell for each ganglion cell.
Fibers from the basolateral nucleus of the amygdala selectively innervate striosomes in the caudate nucleus of the cat
Authors: Ragsdale Clifton W. , Graybiel Ann M.
Published: January 2005

The compartmental organization of the amygdalostriatal projection was studied in the cat by comparing staining patterns seen by cholinesterase enzyme histochemistry with the distribution of fibers labelled with a horseradish peroxidase–wheat germ agglutinin conjugate or by incorporation of 35S‐methionine or 3H‐leucine. Fibers from the basolateral nucleus of the amygdala were found to innervate selectively acetylcholinesterase‐poor striosomes demonstrated in the caudate nucleus and butyrylcholinesterase‐rich zones observed in the anterodorsal nucleus accumbens. In no case were the amygdalar fibers fully restricted to striosomes, but the nature and degree of labelling of the striatal matrix, as well as the range of the labelled fibers in dorsal striatum, varied with the positions of the injection sites.
Pathway specificity of reticulospinal and vestibulospinal projections in the 11‐day chicken embryo
Authors: Glover Joel C. , Petursdottir Gudrun
Published: January 2005

The organization of the axonal pathways of reticulospinal and vestibulospinal projections in the 11‐day chicken embryo was ascertained through retrograde tracing experiments. An in vitro reparation of the brainstem and cervical spinal cord facilitated precisely localized tracer applications. Single‐ and double‐labelling experiments involving high cervical injections of tracers in combination with selective lesions defined the specific pathways by which different brainstem neurons project to the spinal cord. Coherent, and in many cases distinct, groups of reticulospinal and vestibulospinal neurons could thus be identified on the basis of their position and projection pathway. The organization of these groups and their projections in the 11‐day chicken embryo is similar to that in avian and other vertebrate adults and therefore serves as a reference point for studies of path finding by bulbospinal axons during early development.
Serotoninergic innervation of the cat cerebral cortex
Authors: Mulligan Kathleen A. , Törk Istvan
Published: January 2005

Serotoninergic axons in the cat cerebral cortex were demonstrated immunohistochemically with a monoclonal antibody to serotonin (5‐HT). Three types of 5‐HT axons are distinguished at the light microscopic level by differences in their morphology. Small varicose axons are fine (less than 0.5 μm) and bear fusiform varicosities that are generally less than 1 μm in diameter. These axons extend throughout the width of the cortex and branch frequently, giving rise to widely spreading collaterals. Nonvaricose axons are smooth, show a relatively large and constant caliber (about 1 μm), travel in straight, horizontal trajectories, and branch infrequently. Large varicose axons are distinguished by large round or oval varicosities (1 μm or more in diameter) borne on fine‐caliber fibers. These axons often form basketlike arbors around the somata of single neurons. In the simplest basketlike arbors, several large, round varicosities from a small number of axons contact the soma. In complex baskets intertwining collaterals contact the soma and apparently climb along and outline the cell's major dendrites. The patterns revealed by the climbing axons suggest that a variety of nonpyramidal cell types selectively receive dense 5‐HT innervation.

Serial reconstructions of the 5‐HT axons within the cortex show that the large varicose axons arise as infrequent collaterals from the nonvaricose axons. A single nonvaricose parent axon gives rise to several large varicose axon collaterals that may contribute to different basketlike arbors. Conversely, a single basketlike arbor may be formed by large varicose axon collaterals from more than one nonvaricose parent axon. The small varicose axons do not appear to be related within the cortex to either the nonvaricose or large varicose axon types.

The results support the hypothesis that the 5‐HT projection to the cortex is organized into two subsystems, one of which may exert widespread influence in the cortex via highly divergent branches, while the other, with a more restricted distribution, acts on specific classes of cortical neurons.
Catecholamine neurons in the brainstem of the reptile Caiman crocodilus
Authors: Brauth Steven E.
Published: January 2005

Immunohistochemical methods were used to map the distribution of neurons exhibiting tyrosine hydroxylase‐like immunoreactivity (TH) in the brainstem of the reptile Caiman crocodilus.

The results reveal that many catecholamine systems previously described in mammalian and avian species are present in the brainstem of the caiman. Within the medulla, many immunoreactive neurons surround the central canal. This neuronal field extends rostrally to the level of the dorsal motor nucleus of the vagus. Many TH neurons overlap the region of the solitary nucleus, and an extensive system of fibers derived from these neurons extends ventrally and laterally into the region immediately bordering the descending nucleus of the trigeminal nerve Some TH neurons are also present in the ventrolateral tegmentum of the medulla at this level.

A large number of TH cells are present in the pons and midbrain. These include the locus coeruleus, nucleus subcoeruleus ventralis, nucleus subcoeruleus dorsalis, substantia nigra (Brauth et al., '83), and area ventralis of Tsai. The subcoeruleus nuclei are considerably larger in the caiman than in other reptilian species including turtles and lizards and closely resemble the subcoeruleus nuclei of birds in terms of position and anterior‐posterior extent. Within the diencephalon, numerous small, intensely staining, TH‐immunoreactive and CSF‐contacting neurons were observed within the preoptic recess and in close proximity to the ventricular wall at rostral hypothalamic and preoptic levels. Many intensely stained, immunoreactive cell bodies were observed in the medial hypothalamus similar in position to the A13 cell group of mammals. In the subthalamus, TH neurons completely surround the ventral peduncle of the forebrain bundle (which contains fibers of the ansa lenticularis) and extend into the ventromedial and ventrolateral thalamic areas. A rich plexus of TH‐positive axons and terminals invests the external layer of the median eminence.