bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acoustic chiasm II: Anatomical basis of binaurality in lateral superior olive of cat
Authors: Glendenning K. K. , Hutson K. A. , Nudo R. J. , Masterton R. B. 
Published: January 2005

AbstractThe afferent projections to the lateral superior olive (LSO) were examined with horseradish peroxidase, horseradish peroxidase‐wheat germ agglutinin conjugate, 125I‐wheat germ agglutinin and tritiated leucine autoradiography, anterograde axonal degeneration, and 14C‐2‐deoxyglucose methods.The pathway to the ipsilateral LSO orginates in the spherical cells in anteroventral cochlear nucleus. Although some of the fibers pass above the lateral nucleus of the trapezoid body, most pass below it and turn at right angles to enter the LSO either directly through its ventral, lateral, or dorsal borders, or through its ventral or dorsal hilus. They end in unpolarized terminal fields throughout the LSO. Most if not all of these fibers are true collaterals of axons continuing across the midline in the trapezoid body.Verifying Held's (1893) finding of a major direct projection from the cochlear nucleus to the contralateral medial nucleus of the trapezoid body (MTB) and Rasmussen's ('46) finding of a major projection from the MTB to the LSO, the present results illustrate that this two‐neuron pathway probably supplies all but a very small component of the relatively direct input to the LSO from the contralateral ear. This pathway originates in the globular cells of the ventral cochlear nucleus and relays mostly though not exclusively through the “principal cells” in the more rostral parts of the MTB. It terminates mostly in perisomal endings in unpolarized fields throughout the LSO, though most heavily within the (high frequency) medial and middle limbs and less heavily in the LSO's (low frequency) lateral limb.In addition to this indirect pathway, there is a small direct pathway to the contralateral LSO as suggested by Goldberg and Brown ('69) and Warr ('72, '82). This direct pathway to the contralateral LSO, like the direct ipsilateral pathway, probably originates in the spherical cell region of the ventral cochlear nucleus, crosses the midline in the trapezoid body, and terminates in a small circumscribed area within the LSO's ventromedial (high frequency) area.The 2‐deoxyglucose method applied to cats in which the ipsilateral and contralateral pathways have been surgically isolated shows that each of the pathways converging on the LSO is topographically and tonotopically organized with the ipsilateral and the combined contralateral terminations in strict tonotopic register.
Rat medulla oblongata. II. Dopaminergic, noradrenergic (A1 and A2) and adrenergic neurons, nerve fibers, and presumptive terminal processes
Authors: Kalia Madhu , Fuxe Kjell , Goldstein Menek 
Published: January 2005

AbstractThe aim of this study was to determine the anatomical relationships between catecholaminergic neurons and cytoarchitectonically defined nuclei in the caudal medulla oblongata. Previous studies have demonstrated the existence of noradrenergic cell bodies (designated as the A1 and A2 cell groups) in the caudal medulla oblongata of the rat (Dahlström and Fuxe, '64), including the nTS. There, is no information currently available with regard to details of the distribution of these noradrenergic neurons in the functionally distinct subnuclei of the medulla oblongata. In this study the location of catecholamine‐synthesizing enzymes was examined in the serial sections of the caudal medulla oblongata of the rat: tyrosine hydroxylase (TH), dopamine‐beta‐hydroxylase (DBH), and phenylethanolamine N‐methyl transferase (PNMT). The immunoperoxidase method of Sternberger ('79) was used to demonstrate the location of immunoreactive neurons, nerve fibers, and presumptive terminal processes. This was followed by Nissl staining of the same sections to localize accurately the immunoreactivity.Noradrenergic neurons (TH‐ and DBH‐positive and PNMT‐negative) were localized in a number of subnuclei of the nucleus of the tractus solitarius (nTS), the area postrema (ap), and in the dorsal motor nucleus of the vagus (dmnX). The distribution of these noradrenergic cells was different at different rostrocaudal levels. In addition, adrenergic neurone (TH‐, DBH‐, and PMNT‐positive) were identified dorsal to the tractus solitarius (TS), in the dorsal strip region (ds), the periventricular region (PVR), the dorsal parasolitarius region (dPSR), and the dmnX (rostral to obex). In addition, dopaminergic neurons (TH‐positive and DBH‐ and PNMT‐negative) were found in the ap and dmnX. The A1 cell group in the ventrolateral medulla consisted almost exclusively of noradrenergic neurons (TH‐ and DBH‐positive and PNMT‐negative).These results indicate that in the rat the A2 cell group is a mixed population of catecholaminergic neurons that are localized in well‐defined regions of the dorsal medulla oblongata. The distribution of these neurons is very specific both in terms of rostrocaudal levels and cytoarchitectonic subdivisions of regions of the medulla known to be involved in central autonomic control. This supports the hypothesis that monoaminergic neurons in the dorsal medulla play important roles in the central regulation of visceral function.
Mapping increased glycogen phosphorylase activity in dorsal root ganglia and in the spinal cord following peripheral stimuli
Authors: Woolf Clifford J. , Chong Mun Seng , Rashdi Tabassam A. 
Published: January 2005

AbstractA histochemical technique has been used to map the distribution and the relative proportion of the active and inactive form of the enzyme glycogen phosphorylase in the primary afferent cell bodies of lumbar dorsal root ganglia and within the lumbar spinal cord of the rat. The glycogen phosphorylase was found to be present in large and small diameter primary afferent cell bodies and in the grey matter of the spinal cord, except in lamina 2. Most of the glycogen phosphorylase in control rats was in the inactive form. Peripheral innocuous mechanical and thermal stimuli failed to alter the activity of glycogon phosphorylase in the lumbar spinal cord, but noxious mechanical, chemical, and thermal stimuli when applied to the hindlimb of decerebrate rats increased the enzyme activity in the ipsilateral dorsal horn within 10 minutes. The number of primary afferent cell bodies with active glycogen phosphorylase also increased. These changes are likely to be due to the conversion of the inactive “b” form of the enzyme to the active “a” form under the influence of a calcium or cyclic AMP activated phosphorylase b kinase. Pentobarbitone anaesthesia diminished but did not completely suppress the noxious stimulus‐evoked glycogen phosphorylase activity changes.Graded electrical stimulation of the sciatic nerve was performed to simulate the effects of the peripheral noxious stimuli in a controlled fashion. Stimulation at a strength that activated only large myelinated afferents produced no greater effect on the distribution of the active form of the enzyme in the dorsal horn than that produced by exposure of the nerve, but stimulation of the thin myelinated A‐delta afferents and unmyelinated C‐fibres produced a widespread increase in glycogen phosphorylase activity in the spinal cord and in the L4 dorsal root ganglion. The increased activity could be detected after stimulation for as short a period of time as 5 minutes.The mechanisms underlying the stimulus‐evoked increase in glycogen phosphorylase activity in the spinal cord and dorsal root ganglia are not yet known, nor have we positively established which elements in the spinal cord, neurones, or glia are responsible for the changes in the glycogen phosphorylase activity. Nevertheless, it is clear that the neural activity generated by certain types of high threshold input is associated with the activation of glycogen phosphorylase, and this may be a useful tool for studying the spatial distribution of some activity‐related changes in the nervous system. The technique may also help elucidate those circumstances where glycogen reserves are used as an energy source by nervous tissue.
Sensory nerve endings of the incisive papilla of rat hard palate studied by peroxidase cytochemical methods
Authors: Chan Kwan Y. , Byers Margaret R. 
Published: January 2005

AbstractThis study utilized peroxidase cytochemical methods to survey and analyze the distribution, morphology, and functional relationship of the various components of sensory nerve endings in a focal region of the anterior hard palate (incisive papilla) of the rat. The studies included an anatomical survey of this relatively unknown oral structure, confirmation of the trigeminal origin (labeled by retrograde axonal transport of WGA‐HRP injected into the incisive papilla) of the sensory nerve endings, and a complete analysis of the distribution of these nerve endings (labeled by anterograde axonal transport of HRP or WGA‐HRP injected into the trigeminal ganglion). Three methods of fixation and two methods of cytochemical reaction were used for selection of an optimal technique for these studies. The results showed distinct patterns of peroxidase‐labeled sensory nerve endings at three regions of the incisive papilla: (a) dome region (ventral), where labeled nerve endings formed three parallel channels in association with three surface ridges; (b) chemosensory corpuscle enriched region (medial to incisive canal), where 82% of the 30–40 chemosensory corpuscles were labeled; and (c) lateral labium (lateral to incisive canal), where labeled nerve endings formed a circumscribed network guarding the orifice of incisive canal. The discrete organization of multiple sensory nerve endings in the incisive papilla of the rat may provide an easily accessible model system for various studies in sensory physiology.
The central neural connections of the area postrema of the rat
Authors: Shapiro Robert E. , Miselis Richard R. 
Published: January 2005

AbstractWe applied the neuroanatomical tracers cholera toxin‐horseradish peroxidase and wheat germ agglutinin‐horseradish peroxidase to investigate the neural connections of the area postrema (AP) in the rat. We find that the AP projects to the nucleus of the solitary tract (NTS) and dorsal motor nucleus of the vagus bilaterally both rostral and caudal to obex; the nucleus ambiguus; the dorsal aspect of the spinal trigeminal tract and nucelus and the paratrigeminal nucleus; the region of the ventrolateral medullary catecholaminergic column; the cerebellar vermis; and a cluster of structures in the dorsolateral pons which prominently include a discrete set of subnuclei in the lateral parabrachial nucleus. The major central afferent input to the area postrema is provided by a group of neurons in the paraventricular and dorsomedial hypothalamic nuclei whose collective dendrites describe a horizontally oriented plexus which encircles the parvocellular nucleus of the hypothalamus bilaterally. In addition, the caudal NTS may project lightly to the AP. The lateral parabrachial nucleus provides a very light input as well. These connections, when considered in the context of the known vagal afferent input and reduced blood‐brain barrier of AP, place this structure in a unique position to receive and modulate ascending interoceptive information and to influence autonomic outflow as well.
Connections of the lobus inferior hypothalami of the clearnose skate Raja eglanteria (chondrichthyes)
Authors: Smeets Wilhelmus J. A. J. , Boord Robert L. 
Published: January 2005

AbstractThe afferent and efferent connections of the lobus inferior hypothalami of the clearnose skate were demonstrated by the anterograde and retrograde transport of horseradish peroxidase. The main source of afferents is from the midbrain tegmentum and telencephalon. The major midbrain input is from cells of the ipsilateral nucleus tegmentalis laterals and the caudal tegmental area. Another prominent, mostly ipsilateral, projection arises from nucleus F of the isthmic region. A few labeled cells also occur in the nucleus interpeduncularis, nucleus raphes superior, and lateral reticular formation. Afferents from the telencephalon arise from cells of the area preoptica, area superficialis basalis, striatum, nucleus septalis lateralis, and area subpallialis 1. Of the pallial structures, the pallium mediale and anterior as well as posterior subdivisions of the pallium dorsale pars centralis appear to have strong projections to the inferior lobe.Efferent connections of the inferior lobe consist of ascending and descending pathways. Fibers of the main ascending efferent pathway course within the basal forebrain bundle and distribute to subpallial areas. The descending efferent pathways course within the tractus lobobulbaris and tractus lobocerebellaris. Of these, the former is traceable to the level of the facial motor nucleus, issuing fibers enroute to the midbrain tegmentum and to the lateral reticular formation. The lobocerebellar tract courses dorsolateral to the lobobulbar tract, and its fibers terminate within the ipsilateral granular ridge of the rostral pole of the cerebellar corpus.There appears to be a topological organization of the inferior lobe connections. In general, pallial areas project mainly to the lateral subdivision of the inferior lobe nucleus at midlobic levels, whereas connections with the brainstem arise from or terminate within the dorsal and intermediate subdivisions at midlobic as well as caudal levels. The widespread ascending and descending connections indicate that the hypothalamic inferior lobe of the clearnose skate is a major relay center between the telencephalon and brainstem.
Multiple vibrissae sensory regions in rat cerebellum: A (14C) 2‐deoxyglucose study
Authors: Sharp Frank R. , Gonzalez Manuel F. 
Published: January 2005

AbstractRepetitive tactile sensory stimulation of the right mystacial vibrissae (whiskers) was performed in awake, adult rats. Regions of increased (14C) 2‐deoxyglucose (2DG) uptake were mapped autoradiographically in cerebellum. Predominantly ipsilateral activation of multiple discrete granule cell regions occurred in paramedian lobule, crus 2, crus 1, lobulus simplex, and anterior lobe hemisphere. Bilateral and contralateral activation of cerebellum did occur. Multiple small patches, as well as large granule cell regions, were activated. Mossy fiber afferents from the spinal trigeminal nuclei (particularly interpolates), principal trigeminal sensory nucleus, and superior colliculus could account for metabolic activation of the granular layer. The slight metabolic activation of the molecular layer could have occurred from climbing or parallel fibers.Comparisons of the paramedian lobule granule cell regions activated during repetitive sensory stimulation of the vibrissae (RSSV) to those activated during vibrissae motor cortex stimulation (VMIS) showed regions only activated by RSSV, regions only activated by VMIS, and regions activated by both RSSV and VMIS. The granule cell regions activated during RSSV and VMIS were usually adjacent to or overlapping each other. Regions only activated during RSSV or only during VMIS could represent technical problems in trying to compare vibrissae motor and sensory pathways in two different groups of animals. Alternatively, cerebellar regions activated only during RSSV could process vibrissae tactile inputs. Regions activated only during VMIS could process vibrissae motor and perhaps proprioceptive sensory input. Regions activated during both RSSV and VMIS might process vibrissae proprioceptive sensory input and/or might represent loci where vibrissae motor, proprioceptive sensory, and tactile sensory convergence occur. The results raise the possibility that vibrissae motor, proprioceptive sensory, and tactile sensory pathways could be processed in separate granule cell patches in p arts of cerebellum and in the same granule cell patches in other parts of cerebellum.
Ultrastructure of mouse vallate taste buds. I. Taste cells and their associated synapses
Authors: Kinnamon John C. , Taylor Barbara J. , Delay Rona J. , Roper Stephen D. 
Published: January 2005

AbstractThe ultrastructural features of murine vallate taste bud cells and their associated synapses have been examined in thin and thick sections with conventional transmission electron microscopy and high‐voltage electron microscopy. Computer‐assisted reconstructions from serial sections were utilized to aid in visualization of taste bud cell‐nerve fiber synapses.We have classified taste bud cells on the basis of previously established criteria‐namely, size of the nucleus, shape and density of chromatin, density of cytoplasm, and presence or absence of dense‐cored or clear vesicles, other cytoplasmic organelles, and synaptic foci. Both dark cells and light cells are present, as well as cells with intermediate morphological characteristics.Synapses were observed from taste bud cells onto nerve fiber processes. In virtually all instances, synapses are associated with the nuclear region of the taste cell. These synapses are characterized by the presence of 40–70 nm clear vesicles embedded in a thickened presynaptic membrane separated from the postsynaptic membrane by a 16–30 nm cleft. Synapses are not unique to any particular cell type. Dark, intermediate, and light cells all synapse onto nerve fibers. Two general types of synapses exist: spot (or macular) and fingerlike. In the latter, the postsynaptic region of the neuronal process protrudes into an invagination of the taste cell membrane. Differences in synaptic morphology are not correlated with taste cell type. In some cases a single taste cell was observed to possess both macular and fingerlike synapses adjacent to one another, forming a synaptic complex onto a single neuronal process. On the basis of the presence of synaptic contacts, we conclude that both “dark” and “light” cells are gustatory receptors.
Functional organization in cortical barrels of normal and vibrissae‐damaged mice: A (3H) 2‐deoxyglucose study
Authors: Durham Dianne , Woolsey Thomas A. 
Published: January 2005

AbstractThe large mystacial vibrissae on the faces of rodents have punctate representations in all stations in the central trigeminal pathway, including layer IV of the somatosensory cortex (SmI). The cortical whisker correlates, multicellular units termed barrels, are not present at birth, and damage to the vibrissae during the first postnatal week results in altered adult cytoarchitectonics The anatomical effects of vibrissae damage in the cortex have been well documented; here, we investigated the functional organization of altered SmI barrels with a high‐resolution 2‐deoxyglucose (2‐DG) technique (Durham et al., '81, J. Neurosci. 1:519). The middle row of vibrissae was cauterized in 1‐, 2‐, 3‐, 4‐, or 5‐day‐old mice, and the animals were allowed to survive to sexual maturity. Various combinations of vibrissae were clipped acutely 24 hours prior to injection of 2–4 mCi of (3H)2‐DG. Mice actively explored an empty cage for 60 minutes, stimulating the remaining vibrissae. The mice then were perfused and their brains prepared for paraffin histology and emulsion autoradiography.In tangential sections through layer IV, patterns of neuropil and cell body labeling were analyzed with respect to barrel cytoarchitecture in normal and vibrissae‐damaged mice. In both control and experimental animals, patterns of neuropil and cell somata label corresponded exactly to barrel boundaries, whether normal or altered by vibrissae damage. Only those barrels for which vibrissae were intact had high levels of label, with anterior barrels more heavily labeled. Many neurons in the septa between these barrels and the adjacent barrels were labeled also. We found slightly higher neuropil label in the cortical zone corresponding to the damaged zone on the face in animals lesioned at any time. These data indicate that physiological somatotopy in vibrissae‐damaged animals matches the anatomical cytoarchitecture.
Effects of neonatal infraorbital lesions upon central trigeminal primary afferent projections in rat and hamster
Authors: Jacquin Mark F. , Rhoades Robert W. 
Published: January 2005

AbstractTransganglionic and anterograde horseradish peroxidase transport was used to evaluate the central projections of undamaged trigeminal (V) nerve branches in adult rats and hamsters subjected to transection of the infraorbital nerve and to cauterization of the vibrissae follicles at birth. In rats, deafferented regions of the V brainstem nuclear complex did not receive abnormal projections from undamaged mandibular sensory afferents. Undamaged ophthalmic‐maxillary fibers also failed to terminate heavily in the region deafferented by the neonatal infraorbital lesions.In the hamster, on the other hand, neonatal infraorbital nerve lesions were associated with statistically significant increases in mandibular terminal fields in the principalis, subnucleus interpolaris, and subnucleus caudalis.Tracing experiments were also carried out in neonatal rats and hamsters to determine whether the above‐described differences in the response to infraorbirtal nerve damage reflected a difference in the maturity of the V primary afferent projections to the brainstem at the time of our neonatal lesions. In neonatal rats, the infraorbital and mandibular projections to the V brainstem nuclear complex were quite adultlike, both in their pattern and in the extent of their overlap, which was minimal. Overlap between mandibular and infraorbital terminal fields was also minimal in the newborn hamsters.
Efferent connections of the ventral pallidum: Evidence of a dual striato pallidofugal pathway
Authors: Haber S. N. , Groenewegen H. J. , Grove E. A. , Nauta W. J. H. 
Published: January 2005

AbstractPrevious histological and histochemical studies have provided evidence that the globus pallidus (external pallidal segment) as conventionally delineated in the rat extends ventrally and rostrally beneath the transverse limb of the anterior commissure, invading the olfactory tubercle with its most ventral ramifications. This infracommissural subdivision of the globus pallidus or ventral pallidum (VP) is most selectively identified by being pervaded by a dense plexus of substance‐P‐positive striatofugal fibers; the extent of this plexus indicates that the VP behind the anterior commissure continues dorsally over some distance into the anteroventromedial part of the generally recognized (supracommissural) globus pallidus; the adjoining anterodorsolateral pallidal region, here named dorsal pallidum (DP), receives only few substance‐P‐positive fibers, but contains a dense plexus of enkephalin‐positive striatal afferents that also pervades VP. Available autoradiographic data indicate that VP and DP receive their striatal innervation from two different subdivisions of the striatum: whereas VP is innervated by a large, anteroventromedial striatal region receiving substantial inputs from a variety of limbic and limbic‐system‐associated structures (and therefore called “limbic striatum”), DP receives its striatal input from an anterodorsolateral striatal sector receiving only sparse limbic afferents (“nonlimbic” striatum) but instead heavily innervated by the sensorimotor cortex. The present autoradiographic study has produced evidence that this dichotomy in the striatopallidal projection is to a large extent continued beyond the globus pallidus: whereas the efferents of DP were traced to the subthalamic nucleus and substantia nigra, those of VP were found to involve not only the subthalamic nucleus and substantia nigra but also the frontocingulate (and ajoining medial sensorimotor) cortex, the amygdala, lateral habenular and mediodorsal thalamic nucleus, hypothalamus, ventral tegmental area, and tegmental regions farther caudal and dorsal in the midbrain. These findings indicate that the ventral pallidum can convey striatopallidal outflow of limbic antecedents not only into extrapyramidal circuits but also back into the circuitry of the limbic system.