bluuebunny/crossref_metadata_2025_split huggingface dataset:
Descending projections to the mammillary nuclei in the rat, as studied by retrograde and anterograde transport of wheat germ agglutinin–horseradish peroxidase
Authors: Shibata Hideshi 
Published: January 2005

AbstractThe cells of origin and projection fields of the descending afferents to the mammillary nuclei were studied in the rat with retrograde and anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase.The subiculum projects bilaterally to the entire medial mammillary nucleus (MM) in a topographic fashion along the two axes: (1) the proximal part of the subiculum along the presubiculo‐CA1 axis projects to the caudal and lateral regions of the MM whereas the more distal part of the subiculum projects to the medial region; (2) the septal part of the subiculum projects to the caudodorsal region of the MM whereas the more temporal part projects progressively to the more rostroventral regions. The ventral subiculum also projects ipsilaterally to the ventral and lateral margin of the lateral mammillary nucleus (LM). The presubiculum projects bilaterally to the dorsolateral region of the pars posterior of the MM and ipsilaterally to the LM. The infralimbic cortex projects bilaterally to the rostrodorsal region of the MM, whereas the retrosplenial cortex (areas 29a and 29b) projects bilaterally to the medial region at the midrostrocaudal and middorsoventral levels of the MM. The nucleus of the diagonal band projects bilaterally to the caudomedial region of the MM, whereas the lateral septal nucleus projects bilaterally to the pars mediana and the mammillary fiber capsule. A part of the anterior hypothalamic area ventromedial to the fornix projects predominantly ipsilaterally to the rostroventral part of the MM, whereas other basal forebrain regions such as the bed nucleus of the stria terminalis, the medial preoptic and anterior hypothalamic areas, and the area of the tuber cinereum send fibers predominantly ipsilaterally to the mammillary fiber capsule.The results reveal a complex organization of the descending projections to the mammillary nuclei, which may reflect the complex functions of these nuclei within the limbic circuitry.
Quantitative Golgi study of anatomically identified subdivisions of motor thalamus in the rat
Authors: Sawyer Steven F. , Young Stephen J. , Groves Philip M. 
Published: January 2005

AbstractA Golgi study of neurons in the ventroanterior‐ventrolateral complex (VAL) and ventromedial (VM) nucleus in the dorsal thalamus of rats was performed. To facilitate the delineation of subdivisions of these nuclei, some animals received injections of horseradish peroxidase (HRP) into the afferent and efferent fields of VAL and VM, and alternate sections were processed for the histochemical detection of HRP. As an adjunct to subjective observations, a multivariate statistical analysis of morphometric variables was performed to provide an objective assessment of neuronal morphology.All Golgi‐stained neurons in VAL and VM were tentatively identified as projection neurons; no cells with morphological features commonly ascribed to thalamic interneurons were impregnated. Four classes of morphologically distinct neurons were identified in VAL. Type 1 neurons, the most commonly impregnated cell, were found throughout the extent of VAL and resembled “tufted” or “multipolar bush” neurons described previously in many thalamic nuclei. The remaining three neuronal types differed in a number of morphometric parameters and were differentially distributed throughout VAL. Type 2 neurons, distinguished in part by dendritic spine morphology and elongated bipolar dendritic fields, were found only in the rostral sector of the dorsal division of VAL (VALD). Type 3 neurons, characterized by a large and evenly distributed dendritic field, were situated in rostral VAL (all subdivisions). Type 4 neurons had small soma and dendritic dimensions and were located in the ventromedial aspect of the ventral division of VAL (VALV) adjacent to VM. In contrast, the vast majority of neurons in VM were considered to be a single morphological class (similar in form to type 4 neurons in VAL), although a rarely impregnated second type of neuron was also observed.The apparent scarcity of interneurons in VAL and VM is consistent with previous evidence that the synaptic organization of motor thalamus in the rat is markedly different from that of higher‐order mammals. Speculation about the functional attributes of the neuronal types in VAL and VM is necessarily restricted to considerations of afferent and efferent relations, since “motor modality” functions of neurons in these nuclei have yet to be elucidated.
Cellular substrates for interactions between neurons containing phenylethanolamine N‐methyltransferase and GABA in the nuclei of the solitary tracts
Authors: Pickel V. M. , Chan J. , Milner T. A. 
Published: January 2005

AbstractAdrenaline and γ‐aminobutyric acid (GABA) have been implicated in autonomic functions involving the intermediate and caudal portions of the medial nuclei of the solitary tracts (m‐NTS). We sought to determine whether there was a cellular basis for direct intracellular or synaptic interactions between these transmitters in neurons in the m‐NTS of rat brain by using dual‐labeling immunocytochemical methods. Light microscopy revealed immunoautoradiographic labeling for the adrenaline‐synthesizing enzyme phenylethanolamine N‐methyltransferase (PNMT) in perikarya and processes in close proximity to cells demonstrating peroxidase reaction product for GABA. Electron microscopy of the intermediate m‐NTS at the level of the area postrema further established the localization of immunoautoradiographic and peroxidase labels for PNMT and GABA in common as well as separate perikarya and dendrites. All axon terminals were labeled separately for PNMT and GABA. The PNMT‐labeled terminals formed both symmetric and asymmetric synapses, whereas the GABA‐labeled terminals formed exclusively symmetric synapses. Twenty‐four percent (n = 42) of the PNMT‐ and 39% (n = 128) of the GABA‐labeled terminals formed synaptic junctions on unlabeled soma and dendrites. Occasionally both types of terminals converged on a common unlabeled dendrite and on GABA‐labeled dendrites. Only 3% of the PNMT‐ and 12% of the GABA‐containing terminals formed synapses on PNMT‐labeled soma and dendrites, whereas 7% of each type formed synapses with GABA‐labeled profiles. The remaining labeled terminals lacked synaptic relations within the sections examined. The autoradiographic results were confirmed and extended by means of immunogold labeling for PNMT in combination with peroxidase‐antiperoxidase localization of the GABA‐synthesizing enzyme glutamic acid decarboxylase (GAD). GAD‐labeled terminals formed symmetric synapses with dendrites that were either unlabeled or contained low levels of PNMT (gold particles) or PNMT and GAD. We conclude that in caudal, more cardiovascular portions of the NTS, adrenaline and GABA may coexist, but they are more commonly detected in separate populations of neurons having receptive sites for both transmitters and innervating certain common target neurons.
Intrinsic synapses in the ventromedial nucleus of the hypothalamus: An ultrastructural study
Authors: Nishizuka Masako , Pfaff Donald W. 
Published: January 2005

AbstractTo test the ideas that neurons intrinsic to a hypothalamic region might participate in steroid hormone effects and that intrinsic synapses might have unusual morphological features, we deafferented the ventromedial nucleus of the hypothalamus (VMH) in ovariectomized female rats with a Halasz knife. Some rats were given estrogen; others were endocrine controls.The main result of this study was that a large number of synapses in VMH survived the circumscribing cut. In fact, they comprised between one‐half and two‐thirds the number counted in unoperated controls. These were apparently from neuron cell bodies intrinsic to the medial basal hypothalamic island. Their morphology was not clearly different from that expected from unoperated controls or from other brain regions.A significant estrogen effect, an increase in the number of axodendritic synapses per unit area as seen in animals without surgical transections, was not present in the deafferented groups. This suggests that the hormone effect is due to synapses on VMH neurons from cell groups outside the medial basal hypothalamic island. If functional effects of estrogen mediated through VMH do not rely on intrinsic neurons, they must use estrogen‐concentrating neurons that project to other brain regions.
Organization of the septal region in the rat brain: A Golgi/EM study of lateral septal neurons
Authors: Alonso Jose R. , Frotscher Michael 
Published: January 2005

AbstractThe combined Golgi/electron microscope (EM) technique was used to analyze the fine structure and synaptic organization of the various types of neurons in the rat lateral septum (LS), i.e., in the dorsolateral (LSd), intermediolateral (LSi), and ventrolateral (LSv) nuclei of the septal complex.Two characteristic cell types were observed in the LSd: type I with thick, short dendrites densely covered with short spines, and type II with longer and thinner dendrites exhibiting fewer but longer spines. This latter type was by far the most frequently impregnated cell type in the LSd and was also present in the LSi. Synaptic contacts on spines of either cell type were asymmetric; the majority of the presynaptic boutons contained clear and dense‐core vesicles. Typical fusiform neurons with a low number of spines and rather long dendrites, sometimes invading other LS nuclei, were found in the LSi. The LSv contained numerous small neurons with small dendritic fields. A relatively large number of terminals with dense‐core vesicles were found to establish synaptic contacts with identified LSv neurons.The morphological heterogeneity of LS neurons is discussed with regard to other studies on afferent and efferent fiber systems as well as immunohistochemical studies of this particular region of the septal complex.
Localization of serotoninlike‐immunoreactive amacrine cells in the larval tiger salamander retina
Authors: Yang Shu‐zhen , Lam Dominic M.‐K. , Watt Carl B. 
Published: January 2005

AbstractLight microscopic immunocytochemistry was used to study the populations of serotoninlike‐immunoreactive cells in the larval tiger salamander retina. Of 1,135 serotonin‐immunostained cells observed in transverse cryosections, 87% were identified as amacrine cells, whereas 13% were tentatively designated as displaced amacrine cells. The somas of the vast majority of serotonin‐amacrine cells were situated in the innermost cell row of the inner nuclear layer. Only a few serotonin‐immunostained amacrine cell somas were observed in the second row of cells from the inner nuclear layer. Serotonin‐immunoreactive processes generally appeared as a diffuse plexus distributed evenly throughout all levels of the inner plexiform layer.As determined in whole‐mount preparations, serotonin‐amacrine cells were divisible into two populations on the basis of the diameters of their somas. Large cells (45%) ranged from 16 to 19 μm in diameter with the vast majority measuring 17 to 18 μm. Smaller and sometimes less intensely stained cells ranged from 14 to 16 μm in diameter with the large majority measuring 15 μm. The diameters of serotonin‐displaced amacrine cells ranged from 19 to 22 μm with the large majority measuring 20 μm in diameter. An examination of whole‐mount retinas revealed that serotonin‐immunoreactive amacrine and displaced amacrine cells were distributed throughout the center and the periphery of the retina. The density of serotonin‐amacrine cells (large and small combined) was calculated to be 173 ± 4.5 (mean ± standard error) cells per mm2.
Thalamic and extrathalamic connections of the dysgranular unresponsive zone in the grey squirrel (Sciurus carolinensis)
Authors: Gould H. J. , Whitworth R. H. , LeDoux M. S. 
Published: January 2005

AbstractThe connections of the cortical dysgranular “unresponsive zone” (UZ) (Sur et al.: J. Comp. Neurol. 179:425–450, '78) in the grey squirrel were studied with horseradish peroxidase and autoradiographic techniques. The results of these experiments show that the major subcortical connections of the unresponsive zone are in large part reciprocal. Connections are distributed within the thalamus in a poorly defined region including restricted portions of several nuclei that lie along the rostral, dorsal, and caudal borders of the ventral posterior nucleus. Additional thalamic connections of the UZ terminate in the reticular nucleus and are reciprocally related to the paralaminar and central median nuclei. Extrathalamic terminations were observed in the zona incerta, the intermediate and deep layers of the superior colliculus, the red nucleus, and several subdivisions of the pontine nuclei. The similarity between the pattern of subcortical connections of the UZ in the grey squirrel and patterns reported for the parietal septal region in rats (Chapin and Lin: J. Comp. Neurol. 229:199–213, '84) and for area 3a in primates (Friedman and Jones: J. Neurophysiol. 45:59–85, '81), suggests that the UZ in the grey squirrel may represent a counterpart of at least part of area 3a as described in primates. The results are further discussed with respect to a possible role of the thalamus in control or modulation of interhemispheric circuits and of the UZ in the modulation of nociceptive and kinesthetic pathways through the thalamus. Finally, the term parietal dysgranular cortex (PDC) is proposed as an alternative to denote the region currently called the unresponsive zone.
Calcitonin gene‐related peptide immunoreactivity in the cat lumbosacral spinal cord and the effects of multiple dorsal rhizotomies
Authors: Traub Richard J. , Solodkin Ana , Ruda M. A. 
Published: January 2005

AbstractThis study determined the extent of the rostral projection of calcitonin gene‐related peptide‐like immunoreactive (CGRP‐IR) primary afferents in the cat lumbosacral spinal cord. To do this we examined the distribution of CGRP‐like immunoreactivity (CGRP‐LI) contralateral and ipsilateral to multiple dorsal rhizotomies. In the contralateral dorsal spinal cord, CGRP‐IR fibers dwere mostly observed in Lissauer's tract, the dorsal columns, and laminae I, II, and V. Fewer CGRP‐IR fibers were observed in laminae III, IV, and VI and the area around the central canal. The location of the CGRP‐LI suggests that the afferents arose from nociceptors. Unilateral dorsal rhizotomies of five consecutive segments in the lumbar enlargement caused a substantial although incomplete loss of CGRP‐LI in the rhizotomized dorsal spinal cord ipsilateral to the lesions. The majority of the remaining CGRP‐IR fibers were located in Lissauer's tract, the dorsal columns, and the lateral part of laminae I and V. Ventral rhizotomies or an ipsilateral hemisection in the most rostral rhizotomized segment, in addition to the dorsal rhizotomies, had no noticeable effect upon the density or location of the remaining CGRP‐LI. These results suggest that the majority of the CGRP‐LI within the rhizotomized region of spinal cord was contained within branches of small‐diameter primary afferents that entered the spinal cord through intact dorsal roots located caudal to the rhizotomized segments of spinal cord. It is concluded that CGRP‐IR small‐diameter primary afferents are capable of projecting at least five segments beyond their segment of entry and supplying collaterals to the superficial and deeper layers of the dorsal horn involved in the processing of nociceptive information.
Gap junction particle density of horizontal cells in goldfish retinas lesioned with 6‐OHDA
Authors: Baldridge W. H. , Ball A. K. , Miller R. G. 
Published: January 2005

AbstractThe I1 dopaminergic interplexiform cells of the fish retina are believed to modulate horizontal cell coupling by increasing gap junction resistance. Dopamine also modulates the morphology of horizontal cell gap junctions and mimics the effects of light adaptation. To determine whether the light‐dependent changes in gap junction morphology are due to endogenous dopamine release, horizontal cell gap junctions were studied in goldfish retinas lacking dopaminergic neurons.Dopaminergic interplexiform cells were destroyed by intraocular injections of 6‐hydroxydopamine in both eyes. After lesioning, fish were treated in one of four ways: (1) light‐adapted, (2) dark‐adapted (1 hour), (3) light‐adapted and given and intraocular injection of dopamine, or (4) dark‐adapted (1 hour) and injected with dopamine. The effectiveness of lesioning was evaluated by autoradiographic detection of [3H]‐dopamine uptake in the retina of one eye. Retinas in which lesioning of the contralateral eye was deemed effective were processed for freeze‐fracture electron microscopy and the particle density of horizontal cell gap junctions determined.Lesioned retinas, whether light‐ or dark‐adapted, had elevated horizontal cell soma gap junction particle densities compared to lesioned retinas treated with dopamine. These results demonstrate that high soma gap junction particle densities can be correlated with the absence of dopamine and low densities associated with the presence of dopamine. The differences in gap junction particle density between lesioned and lesioned + dopamine‐treatment were similar to differences between nonlesioned dark‐adapted (1 hour) and light‐adapted retinas, respectively. Therefore, the particle density of light‐ and dark‐adapted soma gap junctions suggests a greater release of dopamine in light‐adapted fish than in 1 hour dark‐adapted fish.Gap junctions on axon terminals of horizontal cells in lesioned light‐ and dark‐adapted retinas had reduced particle densities compared to nonlesioned light‐adapted but not to nonlesioned dark‐adapted retinas. However, intraocular injections of dopamine into lesioned eyes did not alter axon terminal gap junction particle densities. This suggests that coupling at the horizontal cell soma and axon terminal may be regulated by different mechanisms.
Central acoustic tract in an echolocating bat: An extralemniscal auditory pathway to the thalamus
Authors: Casseday J. H. , Kobler J. B. , Isbey S. F. , Covey E. 
Published: January 2005

AbstractTo determine the sources and targets of auditory pathways that bypass the inferior colliculus in the mustache bat, we injected WGA‐HRP in the medial geniculate body and related auditory nuclei of the thalamus as well as in the lower brainstem. We used electrophysiological methods to verify that the injection electrode was in an area responsive to sound. The only thalamic injections that produced retrograde transport to cells in auditory nuclei caudal to the inferior colliculus were those that included the suprageniculate nucleus. These injections labeled a group of large multipolar cells lying between the ventral nucleus of the lateral lemniscus and the superior olivary complex. Neurons in this cell group have also been shown to project to the deep layers of the superior colliculus in the mustache bat. The pathway revealed by these studies is almost identical to the “central acoustic tract” in which fibers course medial to the lateral lemniscus and bypass the inferior colliculus to reach the deep superior colliculus and the suprageniculate nucleus.
GABA‐like immunoreactivity of neurons in the chicken diencephalon and mesencephalon
Authors: Granda Rita H. , Crossland William J. 
Published: January 2005

AbstractThe chick brain is a useful model system for studying the ontogeny and phylogeny of neural circuitry, especially that of the visual system. In this study the distribution of cells and processes showing GABA‐like immunoreactivity (GABA+) in the diencephalon and mesencephalon of the posthatch chick was determined immunohistochemically with a polyclonal antibody to GABA and compared with the results of similar studies in mammals. Most of the small GABA+ cells were found in the chick visual centers such as the nucleus lateralis anterior, suprachiasmatic nucleus, ventral lateral geniculate, optic tract, dorsolateralis anterior pars lateralis, lentiformis mesencephali, ectomammillary nucleus, area pretectalis, and the optic tectum. Large GABA+ cells were found in the following nuclei: reticularis superior, posteroventralis thalami, subpretectalis, isthmi pars magnocellularis, interstitiopretectosubpretectalis, mesencephalicus lateralis pars dorsalis. These large cell‐containing nuclei receive projections from visual or auditory centers. GABA+ axons were found throughout the diencephalon and mesencephalon but were especially prominent in the ansa lenticularis, fasciculus medialis longitudinalis, and optic tract. The distribution of GABA+ cells in the chick is more widespread than in rodents and exhibits an increased association with the visual centers suggesting a correlation with the specialized visual requirements of the bird.
GABAergic neurons in brainstem auditory nuclei of the chick: Distribution, morphology, and connectivity
Authors: Von Bartheld Christopher S. , Code Rebecca A. , Rubel Edwin W. 
Published: January 2005

AbstractThe second‐ and third‐order auditory nuclei in the brainstem of the chicken, nucleus magnocellularis (NM) and nucleus laminaris (NL), receive afferents that are immunoreactive to gamma‐aminobutyric acid (GABA). In order to investigate the source(s) of these GABAergic afferents, we examined the distribution, morphology, and connectivity of GABAergic neurons in and adjacent to NM and NL in chicks from 7 days of incubation to 12 days posthatch. Immunocytochemical techniques revealed the presence of approxi‐mately 150 GABA‐labeled neurons within the neuropil surrounding NM and NL on each side of the brainstem. Most of these neurons are located between NM and NL and along the lateral border of NM. GABAergic neurons are mul‐tipolar; their thick dendritic processes branch extensively and give rise to several thin, secondary processes. Frequently, the GABA‐labeled processes arbo‐rize within NM or NL. The morphology of these non‐NM/NL neurons was investigated further with Golgi impregnation and specific neuronal markers (antisera to microtubule‐associated protein). Our observations suggest that a considerable portion of GABAergic input to NM and NL originates from local GABAergic neurons.In order to determine other possible sources of GABAergic input to NM and NL, we injected tracers unilaterally into NM/NL. A small number (20–30)of neurons were retrogradely labeled in the trapezoid body, almost exclusively ipsilaterally. No labeled cells were found in other regions of the brainstem, except for the contralateral NM, Unilateral injections of horseradish‐peroxi‐dase‐labeled wheat germ agglutinin into the paraflocculus revealed only minor terminal labeling in the lateral region of NL bilaterally. The number and dis‐tribution of GABAergic terminals in NM and NL appeared normalafter transection of the crossed dorsal cochlear tract.