bluuebunny/crossref_metadata_2025_split huggingface dataset:
The non‐pyramidal cells in layer III of cat primary auditory cortex (AI)
Authors: Winer Jeffery A. 
Published: January 2005

AbstractThe form and location of non‐pyramidal neurons in layer III of the primary auditory cortex (AI) of adult cats is described in Golgi, Nissl, and other material. The cells were compared to the profiles of retrogradely labeled, commissurally interconnected cells. A principal finding is that certain non‐pyramidal and pyramidal cells project interhemispherically to AI; a second conclusion is that the retrogradely labeled commissural cells form small clusters or narrow strips separated by unlabeled patches even after massive injections in the opposite AI. The non‐pyramidal cells of origin have not yet been conclusively identified, but they must include one (or more) of the following six types of cells observed in Golgi‐impregnated material: (1) tufted or bitufted cells with a radially elongated dendritic arbor; (2) sparsely spinous stellate neurons with thin, smooth dendrites and vertically disposed axonal branches; (3) small stellate cells with varicose dendrites, a restricted dendritic field, and a profusely branched local axon; (4) bipolar neurons with long, thin dendrites; (5) medium‐sized multipolar cells with radiating, sparsely branched dendrites; and (6) small stellate neurons with smooth dendrites and a tiny dendritic field. These non‐pyramidal cells are found throughout layer III but are more numerous in the upper part, layer IIIa, where they mingle with the small pyramidal neurons. As a rule the axonal branches of non‐pyramidal cells are more numerous than those arising from layer III pyramidal neurons, and although they have many axonal collaterals, most project locally and vertically in narrow radial strips. In contrast, pyramidal cell axons have ascending and descending components which invade large, lateral territories in many cortical layers. Layer III non‐pyramidal neurons are similar to those in layer IV in certain respects, although their dendritic fields are more spherical and less tufted than those of layer IV cells, and their axons have more local, limited targets. These axons appear to contribute but little to the conspicuous, lateral fiber striae in layer III. The primary intrinsic targets of non‐pyramidal cell axons appear to be the apical dendrites of medium‐sized and large layer III pyramidal cells, and recurrent branches to the parent cell; their fine, distal branches fortify the vertical plexus in layer III, and certain axons may descend into layer IV. Since layer III in AI receives both commissural and thalamic input, it is possible that these parallel, afferent channels are to some degree segregated, and to some degree convergent, onto particular types of cells. Whether any single cell receives both kinds of input is unknown, but the evidence suggests that not all non‐pyramidal cells project only locally, nor may all project interhemispherically or from AI to AI. This implies that there may be connectionally and perhaps functionally distinct subsets among layer III non‐pyramidal neurons which remain to be identified by experimental methods.
An HRP study of hypothalamo‐cerebellar and cerebello‐hypothalamic connections in squirrel monkey (saimiri sciureus)
Authors: Haines D. E. , Dietrichs E. 
Published: January 2005

AbstractThis study describes the distribution of labeled hypothalamic neurons in squirrel monkey following pressure injections of horseradish peroxidase (HRP) into cerebellar cortex and the pattern of labeling in the cerebellar nuclei subsequent to iontophoretic injections localized in the hypothalamus. Two types of HRP (HRP and a wheat germ agglutinin conjugate, HRP‐WGA) were used as tracers; tetramethylbenzidine was the chromogen.Retrogradely filled neurons were found in lateral (LHAr) and posterior (PHAr) hypothalamic areas, and in the lateral mammillary (LMNu) and supramammillary (SMNu) nuclei following injections into ansiform and paramedian lobules and into the paraflocculus. Labeled cells were occasionally seen in the medial mammillary nucleus (parafloccular cases) and among fascicles of the mammillothalamic tract (all posterior lobe cases) immediately above the medial nucleus. After injections into the anterior lobe, labelling was again found in the LHAr, PHAr, LMNu, and SMNu. In addition, retrogradely filled cells were present in ventromedial, dorsomedial, and dorsal hypothalamic nuclei and in the dorsal hypothalamic area. Labeled cells were occasionally found among fascicles of the fornix along its intrahypothalamic course. In general, labeling extends into slightly more rostral hypothalamic levels in anterior lobe cases when compared to posterior lobe experiments. We interpret these data as indicating that some hypothalamic neurons project directly to the cerebellar cortex (i.e., hypo‐thalamo‐cerebellar fibers); this projection is bilateral with an ipsilateral preponderance.In experiments with injections of HRP‐WGA into the cerebellar nuclei, anterogradely filled axons were traced into the contralateral PHAr and LHAr; this was suggestive of a direct cerebello‐hypothalamic projection. Following iontophoretic injections localized in the LHAr and the medial mammillary nucleus, labeling was seen in the medial (NM), posterior interposed (NIP), and lateral (NL) cerebellar nuclei; this is essentially a contralateral projection. Retrogradely labeled cells were found in the rostral and ventral NM, the ventral and dorsocaudal NL, and diffusely throughout the NIP. On the basis of the known distribution of cerebello‐thalamic fibers and other criteria, these labeled cells are representative of a true cerebello‐hypothalamic projection. It is suggested that the cerebellum, through these pathways, may have a relatively direct influence on visceral centers in the brainstem and spinal cord.
Telencephalic connections in lizards. I. Projections to cortex
Authors: Bruce Laura L. , Butler Ann B. 
Published: January 2005

AbstractThe afferent connections to five cortical regions in two distantly related species of lizards (Gekko gecko and Iguana iguana) were studied by means of retrograde transport of horseradish peroxidase conjugated to wheat germ agglutinin. Each of the five cortical regions is characterized by a specific pattern of projections from telencephalic, thalamic, hypothalamic, and brainstem regions. Subdivisions within the five cortical regions also receive different patterns of projections. The thalamo‐cortical projections are as follows: The small‐celled mediodorsal cortex receives a projection from nucleus dorsolateralis anterior pars magnocellularis. The large‐celled mediodorsal cortex receives projections from nucleus dorsolateralis anterior pars parvicellularis and pars magnocellularis. The dorsal cortex receives a projection from nucleus dorsolateralis anterior pars parvicellularis. The lateral cortex receives a projection from nucleus dorsolateralis anterior pars magnocellularis. The pallial thickening receives projections from nucleus dorsomedialis and nucleus intercalatus. The latter nucleus receives a direct retinal projection. Thus, the pallial thickening is the recipient of a retino‐thalamo‐cortical projection.To date, comparisons of data from experimental studies have suggested that the cortical regions in lizards and turtles may be organized differently. However, the results of the present study suggest that the organization of cortical regions among reptiles is more similar than previously realized.
Telencephalic connections in lizards. II. Projections to anterior dorsal ventricular ridge
Authors: Bruce Laura L. , Butler Ann B. 
Published: January 2005

AbstractThree distinct cytoarchitectonic regions were identified within the anterior dorsal ventricular ridge (ADVR) of two species of lizards, Gekko gecko and Iguana iguana. These regions have been named according to their general topographical positions: medial area, caudolateral area, and rostrolateral area.Injections of horseradish peroxidase throughout the ADVR demonstrated that each of the three areas of the ADVR receives projections from specific thalamic nuclei which are associated with specific sensory modalities. The medial area receives an auditory thalamic projection from nucleus medialis. The caudolateral area receives thalamic projections from nucleus medialis posterior and nucleus posterocentralis. The latter two nuclei were shown to receive projections from the spinal cord and, therefore, are presumed to be associated with body somatosensory information. The rostrolateral area receives a thalamic projection from nucleus rotundus, which receives visual information. In addition, the mesencephalic tegmentum and the thalamic nucleus dorsomedialis project to the entire ADVR. The latter projection is similar to the diffuse cortical projections of the intralaminar thalamic nuclei in mammals.These findings support previous suggestions that the ADVR is comparable to sensory regions of the mammalian neocortex.
On the location and size of laryngeal motoneurons in the cat and rabbit
Authors: Davis P. J. , Nail B. S. 
Published: January 2005

AbstractMotoneurons supplying the posterior crico‐arytenoid (PCA), thyro‐arytenoid (TA), lateral crico‐arytenoid (LCA), and crico‐thyroid (CT) laryngeal muscles were localized in the cat, the rabbit, and the 6‐week‐old kitten by using the technique of intramuscular injection of horseradish peroxidase. Each muscle was found to be innervated by a single, ipsilateral pool of motoneurons, a result which was reliably established only after controlling adventitious spread of the label to nontarget muscles by prior denervation of adjacent musculature. The laryngeal motoneuron column extended in the nucleus ambiguus for a distance of 5–6 mm caudally from the facial nucleus. CT motoneurons were located in the rostral third of this column while the PCA, TA, and LCA motoneurons were located more caudally. These results are in general agreement with earlier degeneration studies (Lawn, '66a; Szentágothai, '43).Although labelled cells were widely dispersed in the nucleus, particularly in the adult cat, a limited amount of topographical structure could still be discerned in the arrangement of recurrent laryngeal nerve motoneurons. In the cat, the PCA pool was located in the ventral part of the recurrent laryngeal nerve representation and did not extend as far caudally as the TA or LCA pools; the LCA pool was located in the caudal and dorsomedial part of the recurrent laryngeal nerve pool; TA motoneurons appeared to overlap the PCA and LCA pools on all three anatomical planes. TA motoneurons were more numerous than PCA or LCA motoneurons, the numbers of cells in the three pools being estimated at 170, 111, and 112, respectively.In the cat bilateral labelling of different pools pointed to certain differences in morphology between cells from these pools and also suggested a functional basis for such differences. The mean soma diameter for the PCA and CT motoneurons was each significantly smaller than that for the TA and LCA motoneurons. The rabbit data were similar. The findings on motoneuron morphology are considered in relation to anatomical and physiological characteristics known to have been established for individual laryngeal muscles and with which they appear to be consistent.
The cytoarchitectonic organization of the spinal cord in the rat. I. The lower thoracic and lumbosacral cord
Authors: Molander C. , Xu Q. , Grant G. 
Published: January 2005

AbstractA laminar Cytoarchitectonic scheme of the lower thoracic and lumbosacral segments of the rat spinal cord is presented in which Rexed's principles for the cat are applied. The material consists of 80‐μm‐thick sections stained with toluidine blue or according to van Gieson and 2‐μm‐thick sections stained with p‐phenylenediamine or toluidine blue. The Cytoarchitectonic organization of the rat spinal cord was found to be basically similar to that of the cat, although certain differences exist—for example, in the extension of the laminae. In addition to the laminar scheme, the distribution of certain cell groups, Lissauer's tract, and the pyramidal tract were investigated.
Interhemispheric connections of visual cortex of owl monkeys (Aotus trivirgatus), marmosets (Callithrix jacchus), and galagos (Galago crassicaudatus)
Authors: Cusick C. G. , Gould H. J. , Kaas J. H. 
Published: January 2005

AbstractInterhemispheric connections of visual cortex were studied in owl monkeys, marmosets, and galagos after multiple injections of horseradish peroxidase into one cerebral hemisphere. Areal patterns of connections were revealed in sections of cortex that was flattened and cut parallel to the surface. Results were related to the locations of known visual areas, especially in owl monkeys, in which more visual areas have been established.The connection patterns in owl monkeys and marmosets are very similar, suggesting that the organization of visual cortex differs little in these two New World simians. Galagos have a basically similar pattern, but the connections are more widespread. In all three primates, connections are not restricted to cortex representing the line of decussation of the retina, and even striate cortex has connections displaced from the border. These connections extend up to 2 mm into area 17 in owl monkeys, and they arc most extensive in galagos, where they form foci that are coextensive with regions of high cytochrome oxidase activity. Connections are concentrated in the caudal half of area 18, but protrusions of connections cross the width of the field. The middle temporal visual area (MT) has unevenly distributed connections throughout, with some increase in density along the border. The dorsomedial visual area (DM) of owl monkeys has connections restricted in the rostral border, and a similar region of sparse connections identifies the probable location of DM in marmosets and galngos. Caudal parts of the dorsolateral visual area (DL) of owl monkeys have dense interhemispheric connections. Other visual areas are characterized by unevenly distributed clumps of connections, suggesting that functions are not uniformly distributed, and that semiregular processing modules exist. The results indicate that most extrastriate visual neurons are subject in interhemispheric influences and support the conclusion that callosal connections are functionally heterogeneous.
Brainstem afferents to the omnipause region in the cat: A horseradish peroxidase study
Authors: Langer Thomas P. , Kaneko Chris R. S. 
Published: January 2005

Abstract“Omnipause” neurons (OPNs), located in the nucleus raphe pontis and the reticular formation, actively suppress saccadic eye movements during intersaccadic intervals. To determine the brainstem afferents that may inhibit the OPNs and thereby allow a saccade to occur, we injected horseradish peroxidase into the raphe pontis of four cats at the site of physiologically identified OPNs. Labeled neurons were found in a number of brainstem nuclei. The greatest concentrations, composed of small to medium‐sized neurons, were located in a group of nuclei around the habenulopeduncular tract, in the rostral mesencephalic reticular formation, in the deep layers of the superior colliculus, and in parts of the subjacent cuneiform and subcuneiform reticular nuclei. Smaller numbers were found in the nucleus reticularis pontis oralis. Caudal to the injection site, labeled neurons were scattered in parts of the nuclei reticularis gigantocellularis, paragigantocellularis dorsalis, and paragigantocellularis lateralis. A few neurons were labeled in a restricted region of the caudal part of the nucleus prepositus hyppglossi and in the nucleus reticularis medullaris ventralis. Larger numbers of neurons were labeled in the dorsal column nuclei and in parts of the cochlear nuclei. Smaller numbers were found in the spinal trigeminal nucleus, the lateral nucleus of the superior olive, and the fastigial nucleus of the cerebellum. The nonreticular brainstem projections may contribute sensory information in a number of modalities since OPNs respond to visual, somesthetic, and auditory stimuli.Our findings indicate a number of regions that may contain neural elements impinging on the OPNs. The best prospects for a saccade initiation signal from one of the labeled populations appear to be the meso‐diencephalic reticular formation and/or the superior colliculus.
Amygdalo‐cortical projections in the monkey (Macaca fascicularis)
Authors: Amaral D. G. , Price J. L. 
Published: January 2005

AbstractAmygdalo‐cortical projections were analyzed in the macaque monkey (Macaca fascicularis) in a series of experiments in which 3H‐amino acids were injected into each of the major divisions of the amygdaloid complex and the anterogradely transported label was demonstrated autoradiographically. Projections to widespread regions of frontal, insular, temporal, and occipital cortices have been observed. The heaviest projections to frontal cortex terminated in medial and orbital regions which included areas 24, 25, and 32 on the medial surface and areas 14, 13a, and 12 on the orbital surface. Lighter projections were also seen in areas 45, 46, 6, 9, and 10. The heaviest projection to the insula terminated in the agranular insular cortex with a decreasing gradient of innervation to the more caudally placed dysgranular and granular insular areas. The projection to this region continues around the dorsal limiting sulcus to terminate in the somatosensory fields 3, 1–2, and SII. Essentially all major divisions of the temporal neocortex receive a projection from the amygdaloid complex with the most prominent projections ending in the cortex of the temporal pole (area TG) and the perirhinal cortex. The entire rostrocaudal extent of the inferotemporal cortex (areas TE and TEO) is also in receipt of an amygdaloid projection. While the rostral superior temporal gyrus (area TA) is heavily labeled in several of the experiments (with light labeling continuing into AI and adjacent auditory association regions) there was little indication of labeling in the caudal reaches of area TA. There was a surprisingly strong projection to prestriate regions of the occipital lobe and, in at least one case, clear‐cut labeling in areas OB and 17. Labeling in the parietal cortex was primarily observed in the depths of the intraparietal sulcus. In all cortical fields, label was heaviest at the border between layers I and II and in some regions layers V and VI also had above background levels of silver grains.
Axonal growth and target selection during development: retinal projections to the ventrobasal complex and other “nonvisual” structures in neonatal Syrian hamsters
Authors: Frost Douglas O. 
Published: January 2005

AbstractIn newborn hamsters, there is a direct retinal projection to the ventrobasal complex, the principal thalamic somatosensory nucleus. The projection decreases precipitously between the second and third postnatal days. A few retinofugal axons remain dorsally along the lateral border of the nucleus on day 4, and none are present thereafter. In neonatal hamsters, retinofugal axons project to additional “nonvisual” nuclei including the periventricular and anterior nuclei of the hypothalamus, zona incerta, substantia nigra, inferior colliculus, pons, and mesencephalic tegmentum. Some of these connections remain in adult hamsters, although in apparently reduced density or relative volume, while others disappear. The contribution of transient connections to the normal morphological or functional development of the brain remains to be clarified. The combined results of this and other studies show that the normally transient retino‐ventrobasal projection is a substrate for abnormal connections in that it can be permanently stabilized by appropriate neurosurgery on the day of birth.
Ultrastructure of the dorsal motor nucleus of the vagus nerve in monkey with a comparison of synaptology in monkey and cat
Authors: McLean John H. , Hopkins David A. 
Published: January 2005

AbstractNeurons of the dorsal motor nucleus of the vagus nerve were studied following injections of horseradish peroxidase into the vagus nerve in a monkey (Macaca fascicularis). In frozen sections, the dorsal motor nucleus appeared to be completely filled by labeled medium‐sized (20–30 μm in long axis) neurons. Labeled dendrites from these neurons often extended outside the borders of the nucleus into the nucleus of the tractus solitarius. In 1 μm thick plastic sections and ultrathin sections of the dorsal motor nucleus, two distinct types of neurons were observed with the light and electron microscope. Medium‐sized neurons with abundant cytoplasm and an oval nucleus were retrogradely labeled with HRP, while small (10–15 μm in long axis) neurons with a paucity of organelles and an invaginated nucleus remained unlabeled. Medium‐sized neurons outnumbered the small neurons by approximately five to one.The synaptic organization of the dorsal motor nucleus in monkey was studied and compared with that in cat. The porportions of different types of axosomatic synapses were similar in both species. Terminals containing round vesicles and making symmetrical or asymmetrical contact with the postsynaptic structure were more common than synaptic terminals containing pleomorphic vesicles. In both species, there was a slightly greater synaptic density on the medium‐sized neurons than on the small neurons. The synaptic density in the monkey dorsal nucleus was greatest on the smallest dendrites in the neuropil and least on the somata.
Effect of a conditioning lesion on axonal sprout formation at nodes of ranvier
Authors: McQuarrie Irvine G. 
Published: January 2005

AbstractThe effect of a conditioning lesion on the time‐course of axonal sprout formation after a subsequent testing lesion was evaluated in myelinated axons of the rat sciatic nerve. Transmission electron microscopy of longitudinal nerve sections was used to examine nodes of Ranvier located 200–500 μm proximal to the testing lesion. The conditioning lesion was a cut of the tibial nerve at the ankle; the testing lesion, made 2 weeks later, was a crush of the sciatic nerve at the hip. Sprouts were defined as unmyelinated evaginations of the nodal axolemma that (1) had reached the basement membrane of the Schwann cell, and (2) were located between the myelin sheath of the distal paranode and the basement membrane. Photomicrographs of the nodes at 9, 18, and 27 hours after the testing lesion were assigned to one of seven categories: normal, retracted, myelin degeneration, axonal degeneration, type A sprout formation (cytoskeleton absent), type B sprout formation (cytoskeleton present), and type B sprout degeneration. By 9 hours after the testing lesion, type B sprout formation was found in 9% of the nodes in control nerves (testing lesion alone) and 33% of those in conditioned nerves (P <.01). A 33% incidence of type B sprout formation was not reached in control nerves until 27 hours after the testing lesion. Since the conditioning lesion was located 50 mm distal to the testing lesion and did not induce neuronal death, earlier sprout formation can be attributed to a neuronal response to the conditioning lesion rather than to a putative factor that arises from pre‐degenerated fibers and acts on newly formed sprouts.