bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology and synaptic connections of crossed corticostriatal neurons in the rat
Authors: Wilson Charles J. 
Published: May 2005

AbstractThe neurons of origin of the bilateral corticostriatal projection arising from the medial agranular cortical field in rats were identified by antidromic activation from contralateral neostriatal stimulation. The same cells were tested for antidromic activation from the contralateral neocortex and for orthodromic responses to stimulation of neocortex of the contralateral hemisphere or ipsilateral rostral thalamus. The neurons were then stained by intracellular injection of horseradish peroxidase. The laminar distribution of these neurons was compared to that of cortical cells stained retrogradely after injection of wheat germ agglutinin/HRP in the ipsilateral or contralateral neostriatum. The morphological features of physiologically identified corticostriatal neurons, their laminar organization, and their responses to stimulation were examined and compared with crossed corticocortical and brainstem‐projecting cells.Crossed corticostriatal cells of the medial agranular cortical field were medium‐sized pyramidal neurons found in the superficial part of layer V and in the deep part of layer III. Their basilar dendritic fields and initial intracortical axon collateral arborizations were coextensive with the layer defined by the distribution of corticostriatal neurons. The apical dendrites were thin and sparsely branched but consistently reached layer I, where they made a small arborization. These morphological features were shared by cortical neurons projecting to contralateral neocortex but not responding antidromically to stimulation of contralateral neostriatum, but they were not shared by brainstem‐projecting cortical cells.Orthodromic responses to contralateral cortical stimulation consisted of brief excitatory postsynaptic potentials that were followed by powerful and longer‐lasting inhibitory postsynaptic potentials. Corticostriatal cells also exhibited small excitatory postsynaptic potentials in response to thalamic stimulation.Many crossed corticostriatal neurons were also commissural corticocortical neurons. The results of reciprocal collision tests showed that this was due to the existence of two separate axonal branches, one projecting to contralateral neocortex and one to contralateral neostriatum. Intracellular staining of these neurons revealed ipsilateral axonal projections to the neostriatum and cortex.
Visual and auditory association areas of the cat's posterior ectosylvian gyrus: Thalamic afferents
Authors: Bowman E. M. , Olson C. R. 
Published: May 2005

AbstractThe feline posterior ectosylvian gyrus contains a broad band of association cortex that is bounded anteriorly by tonotopic auditory areas and posteriorly by retinotopic visual areas. To characterize the possible functions of this cortex and to throw light on its pattern of internal divisions, we have carried out an analysis of its thalamic afferents. Deposits of differentiable retrograde tracers were placed at 17 cortical sites in nine cats. The deposit sites spanned the crown of the posterior ectosylvian gyrus and adjacent cortex in the suprasylvian sulcus. We compiled counts of retrogradely labeled neurons in 12 thalamic nuclei delineated by use of Nissl and acetylcholinesterase stains. We then employed a statistical clustering algorithm to identify groups of injections that gave rise to similar patterns of thalamic labeling.The results suggest that the posterior ectosylvian gyrus contains 3 fundamentally different cortical districts that have the form of parallel vertical bands. Very anterior cortex, overlapping previously identified tonotopic auditory areas (AI, P and VP) receives a dense projection from the laminated division of the medial geniculate body (MGl). An intermediate strip, to which we refer as the auditory belt, is innervated by axons from nontonotopic divisions of the medial geniculate body (MGds, MGvl, MGm, and MGd), from the lateral division of the posterior group (Pol), and from the posterior suprageniculate nucleus (SGp). A posterior strip, to which we refer as EPp, receives strong projections from the LM‐SG complex (LM‐SGa and LMp), and lighter projections from the intralaminar and lateroposterior (LPm and LPl) nuclei. On grounds of thalamic connectivity, EPp is not obviously distinguishable from adjacent retinotopic visual areas (PLLS, DLS, and VLS), and may be regarded as forming, together with these areas, a connectionally homogeneous visual belt.
Cholinergic projections from the midbrain reticular formation and the parabigeminal nucleus to the lateral geniculate nucleus in the tree shrew
Authors: Fitzpatrick D. , Conley M. , Luppino G. , Matelli M. , Diamond I. T. 
Published: May 2005

AbstractThe distribution and sources of putative cholinergic fibers within the lateral geniculate nucleus (GL) of the tree shrew have been examined by using the immunocytochemical localization of choline acetyltransferase (ChAT). ChAT‐immunoreactive fibers are found throughout the thalamus but are particularly abundant in the GL as compared to other principal sensory thalamic nuclei (medial geniculate nucleus, ventral posterior nucleus). Individual ChAT‐immunoreactive fibers are extremely fine in caliber and display numerous small swellings along their lengths. Within the GL, ChAT‐immunoreactive fibers are more numerous in the layers than in the interlaminar zones and, in most cases, the greatest density is found in layers 4 and 5. Two sources for the ChAT‐immunoreactive fibers in the GL have been identified–the parabigeminal nucleus (Pbg) and the pedunculopontine tegmental nucleus (PPT)–and the contribution that each makes to the distribution of ChAT‐immunoreactive fibers in GL was determined by combining immunocytochemical, axonal transport, and lesion methods. The projection from the Pbg is strictly contralateral, travels via the optic tract, and terminates in layers 1, 3, 5, and 6 as well as the interlaminar zones on either side of layer 5. The projection from PPT is bilateral (ipsilateral dominant) and terminates throughout the GL as well as in other thalamic nuclei. Lesions of the Pbg eliminate the ChAT‐immunoreactive fibers normally found in the optic tract but have no obvious effect on the density of ChAT‐immunoreactive fibers in the contralateral GL. In contrast, lesions of PPT produce a conspicuous decrease in the number of ChAT‐immunoreactive fibers in the GL and in other thalamic nuclei on the side of the lesion but have no obvious effect on the number of ChAT‐immunoreactive fibers in the optic tract. These results suggest that there are two sources of cholinergic projections to the GL in the tree shrew which are likely to play different roles in modulating the transmission of visual activity to the cortex. The Pbg is recognized as a part of the visual system by virtue of its reciprocal connections with the superficial layers of the superior colliculus, while the PPT is a part of the midbrain reticular formation and is thought to play a non‐modality‐specific role in modulating the activity of neurons throughout the thalamus and in other regions of the brainstem.
Localization of tyrosine‐hydroxylase‐like‐immunoreactive amacrine cells in the larval tiger salamander retina
Authors: Watt Carl B. , Yang Shu‐Zhen , Lam Dominic M. K. , Wu Samuel M. 
Published: May 2005

AbstractImmunocytochemistry was used to localize the populations of tyrosinehydroxylase‐like (TH)‐immunoreactive cells in the tiger salamander retina. Ninety percent of these cells possessed somas that were situated in the innermost cell row of the inner nuclear layer and were classified as amacrine cells. Ten percent of TH‐immunoreactive somas were located in the ganglion cell layer and were tentatively designated as those of displaced amacrine cells. The processes of TH‐immunoreactive cells ramified most heavily in sublayer 1 of the inner plexiform layer, while a relatively small number of TH‐labelled processes distributed in sublayers 3 and 5. Less than 1% of TH‐immunoreactive cells in the amacrine cell layer exhibited a short process of somal origin that extended distally toward the outer plexiform layer. However, these processes did not cross the whole of the inner nuclear layer, and no immunolabelling was observed in the outer plexiform layer.An examination of retinal whole‐mounts revealed that TH‐immunoreactive amacrine and displaced amacrine cells were distributed throughout the center and periphery of the retina. The density of TH‐immunolabelled amacrine cells was calculated to be 49 ± 13 (mean ± standard error) cells per mm2. The vast majority of TH‐immunoreactive amacrine and displaced amacrine cells exhibited a stellate appearance and gave rise to three or more primary dendrites. A few TH‐amacrine and displaced amacrine cells possessed two primary dendrites that emerged from opposite sides of their somas. The processes of TH‐immunoreactive cells were generally poorly branched and varicose with terminal branches sometimes appearing thin and beaded. Because some TH‐immunolabelled processes were very long, there was considerable overlap between the dendritic fields of neighboring TH‐cells. Lastly, individual TH‐immunoreactive amacrine and displaced amacrine cells were often observed in whole‐mounts to provide processes that ramified at more than one level of the inner plexiform layer.
Cholinergic neurons within the rat hippocampus: Response to fimbria‐fornix transection
Authors: Blaker S. N. , Armstrong D. M. , Gage F. H. 
Published: May 2005

AbstractThe distribution and morphologic characteristics of choline acetyltransferase (ChAT)‐containing neurons were studied throughout the rostrocaudal extent of the rat hippocampus and in a midline area just dorsal to the dorsal hippocampus. Peroxidase reaction product was observed with the aid of immunohistochemical methods and a high‐titer polyclonal antibody against ChAT, the acetylcholine biosynthetic enzyme. ChAT‐positive cells in the hippocampus were characterized by small, round or oval perikarya with two or more proximal processes. They were located within the caudal and temporal hippocampal formation, predominantly within the subiculum, in the stratum lacunosum moleculare, at the border of the stratum lacunosum moleculare and the stratum radiatum, and in the molecular layer of the dentate gyrus. The cells resembled in morphology the small, bipolar and multipolar neocortical ChAT‐immunoreactive cells. In addition to the hippocampus, ChAT‐positive neurons were observed caudally in a region just above the dorsal hippocampal commissure and rostrally in the columns of the fornix. These cells were large with an oval perikarya and darkly labeled compared to neurons in the hippocampus. They more closely resembled the ChAT‐positive neurons in the midline raphe of the medial septal nucleus.Examination of the rat hippocampus 2 and 8 weeks following unilateral lesioning of the fimbria‐fornix and supracallosal striae revealed a sparse innervation of ChAT‐positive fibers in the hippocampus ipsilateral to the lesion. ChAT‐labeled neurons in the hippocampus did not appear to sprout in response to the lesion. In contrast, ChAT‐positive cells in the midline did appear to sprout into the medial dorsal subiculum and dorsal medial hippocampus. We conclude that these two populations of cells are distinct with respect to their response to hippocampal denervation and, furthermore, that this distinction may be attributed to a differential response to nerve growth factor.
CRF‐containing neuron systems in the rat hypothalamus: Retrograde tracing and immunohistochemical studies
Authors: Kawano Hitoshi , Daikoku Shigeo , Shibasaki Tamotsu 
Published: May 2005

AbstractBy employing a combination of the immunohistochemistry for rat corticotropin‐releasing factor (rCRF) and retrograde tracing with biotinylated wheat germ agglutinin (b‐WGA) injected into the posterior pituitary (group 1) or into the middle portion of the median eminence (group 2), functionally different populations of CRF neurons were identified in the rat hypothalamus. In the group 1 animals, WGA‐labeling was seen not only in the posterior lobe but also in the intermediate lobe, in which CRF fibers exist. In these animals, WGA‐labeling occurred for almost all large neurons in the anterior commissural, paraventricular (PV), and supraoptic (SO) nuclei, some of the neurons showing a slight immunoreactivity for anti‐rCRF. Conversely, CRF positive neurons appeared in large numbers, some being labeled with WGA, in the caudal periventricular region (CPR), and in the dorsomedial to lateral hypothalamic area (DLH), especially in the latter. In the group 2 animals, WGA was disparsed throughout the subependymal, internal, and external layers of the medial portion of the median eminence, and was taken up by many small cells in the PV, almost half of the cells being immunoreactive for CRF. Slight WGA‐labeling further occurred in some large neurons of the PV and SO, and in some cells of the DLH. It is concluded that hypophysiotropic CRF existing in the external layer of the median eminence originates from small neurons located in the PV, whereas CRF distributed in the posterior and intermediate pituitary originates from the magnocellular PV and SO, and from some neurons in the DLH and CPR.
Organization of the inner plexiform layer of the turtle retina: An electron microscopic study
Authors: Guiloff Gloria D. , Jones Jill , Kolb Helga 
Published: May 2005

AbstractWe have performed a serial‐section electron microscopic study of the inner plexiform layer (IPL) of the retina of the turtle Pseudemys scripta elegans. A qualitative and quantitative assessment of the neuropil of the IPL has been done from photomontages taken from the linear visual streak area and peripheral retina.Counts of conventional, ribbon, serial, and reciprocal synapses, of ganglion cell dendrites, and of profiles containing large, dense‐cored vesicles were made in five equal‐thickness strata in each montage. Averages of these different features were plotted for each stratum in the linear visual streak and compared with peripheral retina. The trend was for stratum 2 to have the highest overall absolute number of amacrine and bipolar interactions, and also of serial synapses, both in the linear visual streak and in peripheral regions. Stratum 4 tended to have the second‐highest number of synapses. The total number of synapses for the entire thickness of the IPL, regardless of stratification, is higher in the streak than in the periphery. The total amacrine‐to‐bipolar‐synapse ratio in the IPL is the highest of any vertebrate studied to date (11.0 in the streak and 14.5 in the periphery) but the number of synapses\μm2 was found to be similar to that reported for other vertebrates. Amacrine‐to‐amacrine synaptic contacts greatly outnumber other types of synapses; amacrines constitute the principal input to ganglion cells, whereas bipolar output is mainly onto amacrines.The trend for higher numbers of synaptic interactions in strata 2 and 4 of the streak region of the turtle IPL can be correlated with the branching of small‐field amacrine and ganglion cells described in Golgi studies (Kolb: Philos. Trans. R. Soc. Lond. B 298:355–393, 82). In peripheral retina, branching of large‐field amacrines and a lower number of bipolar pathways may account for the trend for larger numbers of amacrine synapses in strata 2 and 4. Profiles having large, dense‐cored vesicles tend to occur most frequently in strata 1 and 5, which correlates well with the stratification in the IPL of the processes of immunoreactive amacrine cells described in other studies.
Neuropeptide‐ and neurotransmitter‐related immunoreactivities in the developing rat olfactory bulb
Authors: Matsutani Shinji , Senba Emiko , Tohyama Masaya 
Published: May 2005

AbstractThe development of neuropeptide and neurotransmitter‐related immunoreactivities in the rat olfactory bulb were investigated immunohistochemically by using antisera raised against substance P (SP), cholecystokinin‐8 (CCK), neurotensin (NT), leucine‐enkephalin or methionine‐enkephalin‐Arg6‐Gly7‐Leu8 (ENK), somatostatin (SOM), neuropeptide Y (NPY) and tyrosine hydroxylase (TH).Results obtained for the adult olfactory bulb confirmed previous observations, except for SP‐like immunoreactive (SP‐IR) granule cells in the main olfactory bulb (MOB) and NT‐IR neurons around the modified glomerular complex (MGC) (Teicher et al., Brain Res. 194:530‐535, 1980).SP‐, CCK‐ and NT‐IR neurons were observed in the MOB of the rat fetus. SP‐IR neurons also appeared in the accessory olfactory bulb (AOB). Among them, NT‐IR neurons in the MOB and SP‐IR neurons in the AOB were observed on embryonic day 16. SP‐ and CCK‐IR neurons in the MOB appeared on embryonic day 18. Most of these neurons were presumed to be projecting neurons. SOM‐, NPY‐, ENK‐ and TH‐IR neurons appeared in the newborn rats. The number and intensity of immunostaining of these neurons continued to increase with age, producing the adult pattern, except for NT‐IR neurons in the MGC and SP‐IR neurons in the mitral cell layer of the AOB, which were more numerous and intensely stained in young animals.
Synaptic organization of anomalous retinal projections to the somatosensory and auditory thalamus: Target‐controlled morphogenesis of axon terminals and synaptic glomeruli
Authors: Campbell Gregor , Frost Douglas O. 
Published: May 2005

AbstractThese experiments examine which morphological features of axon terminals and their synaptic glomeruli are determined by afferent axons, and which by their targets. In normal, adult hamsters, electron microscopy reveals that, with respect to multiple ultrastructural features, the terminals and synaptic glomeruli of retinal afferent axons in the dorsal lateral geniculate nucleus differ from those of ascending auditory and somatosensory afferents in the medial geniculate and ventrobasal nuclei, respectively. These features include: (1) the location of specific sensory axon terminals on the somata and dendrites of their targets neurons, (2) the constitutents of the glomeruli and their synaptic relationships, (3) the number of specific sensory terminal boutons per glomerulus, (4) bouton size, (5) the number of dendritic and somatic appendages contacted by each bouton, and (6) the mitochondrial morphology of the specific sensory afferent boutons.In order to ascertain which of these features are determined by afferent axons and which by their targets, we subjected newborn Syrian hamsters to surgical procedures known to produce permanent, abnormal retinal projections to the main thalamic auditory (medial geniculate) and somatosensory (ventrobasal) nuclei. When the animals were adults, we examined the terminals and synaptic glomeruli of abnormal retino‐auditory and retino‐somatosensory axons that were anterogradely labeled by intraocular injection of horseradish peroxidase. With respect to all of the preceding features except mitochondrial morphology, the terminals and synaptic glomeruli of retino‐medial geniculate and retino‐ventrobasal axons more nearly resembled those of normal, auditory and somatosensory afferent axons, respectively, than they did those of normal, retino‐lateral geniculate axons.These results demonstrate that the differentiation of all the features that we have examined, except mitochondrial morphology, is determined by factors in target neurons or their environment. This finding suggests that the differentiation of morphological features involved in contacts among neurons (including the type, number and size of interconnected neuronal elements and the loci at which they contact each other) is responsive to interactions among the connected elements, or between neural elements and their environment (e.g., glia, extracellular matrix), whereas the differentiation of structures reflecting intrinsic functions of individual neuronal elements is not responsive to such interactions.
Ventral striatopallidal parts of the basal ganglia in the rat: I. Neurochemical compartmentation as reflected by the distributions of neurotensin and substance P immunoreactivity
Authors: Zahm D. S. , Heimer L. 
Published: May 2005

AbstractThe distribution of neurotensin immunoreactivity in the basal ganglia of the adult rat was evaluated by studying alternate serial vibratome sections that were exposed to antiserum against neurotensin, substance P, or cholecystokinin. It was observed that a heterogeneous distribution of neurotensin‐immunoreactive fibers and terminals contributes to the neurochemical compartmentation of the ventral pallidum and ventral striatum, and that significant numbers of neurotensin‐immunoreactive neurons occupy striatal districts of the olfactory tubercle, nucleus accumbens, and ventromedial caudate‐putamen. An intense band of pallidal neurotensin immunoreactivity characterizes the medial part of the ventral pallidum adjacent to the nucleus accumbens, whose medial boundary is conveniently defined in sections incubated with cholecystokinin antiserum. Electron microscopic studies showed that the pallidal plexus of neurotensin‐immunoreactive elements consists primarily of boutons, which contact large dendrites in arrangements that in all respects appear to be of the classical striatopallidal variety. A gradual decrese in immunolabel was observed approaching the lateral parts of the ventral pallidum, which display sparse neurotensin immunoreactivity. The results thus indicate the existence of a significant neurotensinergic striatopallidal pathway confined primarily, if not exclusively, to the medial part of the ventral striatopallidal system. The contribution of neurotensin‐immunoreactive fibers and terminals to the compartmentation of ventral striatum is expressed most vividly in their exclusion from clusters of tightly packed medium‐sized neurons, many of which are intensely substance P immunoreactive. Such clusters appear identical with those previously described as rich in opiate receptors and poor in acetylcholinesterase activity. In the ventral striatal region where the nucleus accumbens and ventromedial caudate‐putamen merge, neurotensin‐immunoreactive neurons are organized in clusters. Further rostral in the nucleus accumbens, they are more evenly distributed. Few were found in the dorsolateral quadrant of the neostriatum.