bluuebunny/crossref_metadata_2025_split huggingface dataset:
Membrane area and dendritic structure in type‐identified triceps surae alpha motoneurons
Authors: Cullheim S. , Fleshman J. W. , Glenn L. L. , Burke R. E. 
Published: January 2005

AbstractThe size and branching structure of the dendritic tree were studied in nine type‐identified triceps surae α‐motoneurons that were labeled intracellularly with horseradish peroxidase and reconstructed from serial sections in the light microscope. The average total membrane area (AN) for motoneurons of type S (slow‐twitch) motor units was about 22% smaller than AN for cells of type F units (including both FF and FR motor unit types in this category) (480.1 × 103μml;m2 vs. 617.7 ×103 μm2, respectively). Systematic correlations were found between stem dendrite diameter and three measures of dendritic size: dendrite membrane area, combined dendritic length, and number of terminations. All of these correlations were significantly different for the dendrites of F and S montoneurons. Power‐function relations between stem diameter and dendritic membrane area were used to estimate AN for a sample of 79 type‐identified motoneurons. Mean estimated AN values were significantly different for the F and S motoneuron groups, despite a large overlap in AN values between these groups.The branching structure of dendrites of F and S motoneurons also showed clear differences. Type S motoneuron dendrites showed less‐profuse branching and a more‐even radial distribution of branch points than found in type F cells. Examination of two forms of the “3/2 power rule” for the relation between the diameters of parent and daughter dendritic branches at branch points showed that the dendrites of type S motoneurons conform less well with the anatomical constraints necessary to represent binary branching trees as equivalent cylinders than do dendrites of type F cells. There was no systematic difference between F and S motoneuron dendrites in the degree of asymmetry of first‐order daughter trees. The results overall indicate that the dendrites of F and S motoneuron groups are structurally different, giving rise to a systematic difference in AN between these groups. Such structural differences suggest that the F and S groups of α‐motoneurons can be viewed as intrinsically distinct cell types and not just large vs. small variants of the same cell species.
Three‐Dimensional architecture of dendritic trees in type‐identified α‐motoneurons
Authors: Cullheim S. , Fleshman J. W. , Glenn L. L. , Burke R. E. 
Published: January 2005

AbstractWe have studied the spatial distribution of dendrites of type‐identified triceps surae α‐motoneurons, labeled intracellularly with HRP, using a variety of analytical approaches that were designed to quantify the ways in which dendrites occupy three‐dimensional space. All of the methods indicated a strong tendency for motoneuron dendrites to project radially. However, regions dorsal and ventral to the somata contained fewer dendritic elements, and less membrane area, than expected for complete radial symmetry. Individual dendrites projecting into these regions tended to be smaller than those projecting rostrocaudally or mediolaterally. Nevertheless, the center of mass of membrane area for five of six fully analyzed cells was within 100 μm of the soma and, in all six cells, was located in the same dorsoventral plane as the cell soma. Maps of the projection of dendritic branches onto concentric shells at various radial distances from the soma showed that some regions have high concentrations of branches, sometimes with considerable overlap between branches arising from different stem dendrites, while other regions have relatively few branches, or none at all. Each motoneuron exhibited a different pattern of projection and there were no systematic differences between fast‐twitch (type F, including both types FF and FR units) and slow‐twitch (type S) motoneurons evident in the patterns of dendritic concentration. Assessment of the three‐dimensional territories of individual dendrites showed that dendrites with larger numbers of terminal branches tended to have larger spatial territories. Despite considerable scatter, the results suggest that the density of branches tends to be approximately the same in large and small dendrites, and in F and S cell groups. The results are discussed in relation to the spatial location of synaptic input to motoneurons.
Distribution of luteinizing hormone‐releasing hormone in the nervus terminalis and brain of the mouse detected by immunocytochemistry
Authors: Schwanzel‐Fukuda Marlene , Garcia Maria Soledad , Morrell Joan I. , Pfaff Donald W. 
Published: January 2005

AbstractImmunoreactive luteinizing hormone‐releasing hormone (LHRH) was localized in a relatively large number of ganglion cells and fibers of the nervus terminalis of neonatal and adult mice, indicating that this nerve is a substantial source of LHRH in the mouse brain.Whole‐head specimens of neonatal mice, prior to calcification of the cranium, revealed an extensive distribution of LHRH neurons and fine fibers throughout the peripheral, intracranial, and central parts of the nervus terminalis. The most striking difference between the neonatal and adult animals, in the nervus terminalis, was the increase in immunoreactive axons that made up the fiber bundles of this nerve. In the adult mouse, the intracranial and central projections were composed of thick fascicles of immunoreactive axons, ensheathed by glial cells and accompanied by ganglia that contained both LHRH‐reactive and nonimmunoreactive neurons. LHRH‐immunoreactive cells and axons were seen in a branch of the nervus terminalis that coursed along the medial, posterodorsal aspect of the olfactory bulb and in branches of this nerve that accompany the vomeronasal nerves to the accessory olfactory bulb. A few LHRH neurons and many immunoreactive processes were seen in the accessory and main olfactory bulbs.LHRH‐reactive neurons were seen in the hypothalamus and extrahypothalamic structures. Examination of adult mouse brains revealed a pattern of distribution and number of immunoreactive neurons similar to that seen in the neonate. However, many more LHRH‐reactive axons were seen in all areas of the brain of the mature animal.
Somatosensory nuclei in the brainstem of the rat: Independent projections to the thalamus and cerebellum
Authors: Mantle‐St. John Louise A. , Tracey David J. 
Published: January 2005

AbstractThe dorsal column nuclei and the sensory trigeminal nuclei project not only to the ventrobasal thalamus but also to the cerebellum. In this study the numbers and distribution of neurones projecting to these two regions were examined for the following nuclei: the rostral part of the main cuneate nucleus, the external cuneate nucleus, nucleus x, the principal sensory nucleus of the trigeminal nerve, and the oral, interpolar, and caudal subnuclei of the spinal nucleus of the trigeminal nerve.A thalamic projection from nucleus x and from the external cuneate nucleus was confirmed, and a distinct group of neurones projecting to the ventroposteromedial thalamus was distinguished near the ventromedial aspect of the principal sensory nucleus.Of the 165,000 neurones examined, only one was found to be double labelled. It was concluded that the populations of neurones that project to the ventrobasal thalamus and to the cerebellum are separate, and that somatosensory neurones in the brainstem do not send axon collaterals to both regions.
A quantitative study of morphological reorganization following chronic optic deafferentation in the adult cat dorsal lateral geniculate nucleus
Authors: Somogyi J. , Eysel U. , Hamori J. 
Published: January 2005

AbstractNeuronal and synaptic reorganization in the lateral geniculate nucleus (dLGN) of adult cats following chronic visual deafferentation has been investigated with the aid of GABA immunocytochemistry and quantitative electron microscopy. The main purpose of this study was to establish the morphological counterpart of the functional plasticity of dLGN relay cells after total visual deafferentation (Eysel: Brain Res. 166:259–271, '79). The results provide evidence that the regained excitability of relay cells is not the result of disinhibition (caused hypothetically by the selective loss of GABAergic cells) since the proportion of GABA‐positive and GABA‐negative cells as well as the inhibitory synaptic density did not change. The alternative suggestion that the enhanced excitability could be the result of compensatory axonal sprouting by corticothalamic fibers had also to be dropped: the absolute number of corticothalamic axons to the deafferented dLGN remains unchanged. Because of shrinkage of the dendritic trees of dLGN neurons, however, the density of cortical synaptic input at dLGN cells becomes elevated by almost 60%. It is suggested that the regained excitability of relay neurons is the consequence of the combined effects of (1) adaptive (structural) reduction in size (“atrophy”) of retinally denervated nerve cells, and, as a consequence, (2) increase of input resistance, (3) reduced shunting effects, and (4) relative increase in density of the excitatory cortical input per neuron.
Analysis of the habenulopetal enkephalinergic system in the rat brain: An immunohistochemical study
Authors: Shinoda Koh , Tohyama Masaya 
Published: January 2005

AbstractThe enkephalinergic afferent system in the rat habenula was examined by the indirect immunofluorescence method with antibodies against leucine‐enkephalin.Leucine‐enkephalin‐like immunoreactive (L‐ENKI) fibers were observed in the dorsal portion of the medial habenular nucleus (MHb), the intermediate portion of the lateral habenular nucleus (LHb), and the border zone between the MHb and the LHb (BZHb).Knife‐cut studies demonstrated that almost all the fibers were supplied via the stria medullaris. Also two discrete ENKergic afferents to the MHb and the LHb were found by several kinds of lesion studies: (1) the MHb was ipsilaterally innervated from L‐ENKI neurons in “septoperiventricular area,” which is the junctional area between the ventral supracommissural septum and the rostral thalamic periventricular region. (2) The LHb was ipsilaterally innervated from L‐ENKI neurons in the rostral portion of the lateral hypothalamus. Our findings also suggested that the L‐ENKI fibers in the BZHb are supplied via the stria medullaris with an ipsilateral predominance and that, at the most caudal level, they arise not only from the ipsilateral stria medullaris but also from the contralateral stria medullaris via the habenular commissure.
Immunocytochemical localization of GABA‐, cholecystokinin‐, vasoactive intestinal polypeptide‐, and somatostatin‐like immunoreactivity in the area dentata and hippocampus of the rat
Authors: Sloviter Robert S. , Nilaver Gajanan 
Published: January 2005

AbstractHippocampal neurons containing GABA‐, cholecystokinin(CCK)‐, vasoactive intestinal polypeptide(VIP)‐, or somatostatin(SS)‐like immunoreactivity (LI) were localized in sections of rat hippocampus. GABA‐, CCK‐, VIP, and SS‐LI are found exclusively in interneurons of the area dentata and hippocampus. In the area dentata, GABA‐LI occurs in cells of all strata but predominates in type 1 and 2 basket cells. CCK‐LI is present in a subset of these basket cells and some hilar cells. VIP‐LI is present in a distinct subset of dentate interneurons that, unlike the type 1 and 2 basket cells, do not contribute to the fiber plexus in the inner molecular layer. These VIP‐LI interneurons send their axons to nearby granule cells and form a plexus in the hilus. SS‐LI, although rare in cells of the molecular and granular layers, is present in a large population of hilar interneurons that do not exhibit GABA‐, CCK‐, or VIP‐LI. In area CA3 of the hippocampus, a variety of morphologically diverse interneurons containing GABA‐, CCK‐, VIP‐, or SS‐LI are present in all strata. In area CA1, SS‐LI is present mainly in cells of strata oriens and pyramidale. GABA‐CCK‐ and VIP‐LI interneurons are present in all strata of CA1 but, unlike the SS‐LI cells, are most numerous in strata pyramidale and radiatum. These findings in the area dentata, taken together with those of Kosaka et al. (J. Comp. Neurol. 239:967–969, '85), indicate that two main populations of interneurons can be discriminated on the basis of the substances they contain. One is a group of GABA‐LI cells, some of which also contain CCK‐ and/or VIP‐LI. These cells innervate the granule cells and the second group of interneurons, the SS‐LI hilar cells, which apparently form part of the dentate ipsilateral associational/commissural projections.
Effects of corpus callosum section on functional compensation in the posteromedial lateral suprasylvian visual area after early visual cortex damage in cats
Authors: Tong Lillian , Spear Peter D. , Kalil Ronald E. 
Published: January 2005

AbstractA visual cortex lesion made in adult cats leads to a loss of direction selectivity and a loss of response to the ipsilateral eye among cells in posteromedial lateral suprasylvian (PMLS) cortex of cats. However, a visual cortex lesion made in young cats results in normal direction selectivity and normal ocular dominance in PMLS cortex. Thus cats with an early lesion demonstrate functional compensation in PMLS cortex. The present experiment determined whether the functional compensation depends upon an intact corpus callosum.Cats received a unilateral visual cortex lesion on the day of birth (day 1) or at 8 weeks of age. When the cats were adult, the corpus callosum was sectioned and 24 hours later recordings were made in PMLS cortex ipsilateral to the visual cortex lesion. Results were compared to cats with a similar lesion and an intact corpus callosum.In cats with a lesion made on day 1, a corpus callosum section did not affect receptive‐field properties or ocular dominance in PMLS cortex. Therefore, functional compensation is not dependent on input via the corpus callosum in these animals. However, in cats with a lesion made at 8 weeks, a corpus callosum section resulted in a decrease in the percentage of direction‐selective cells and in the percentage of cells driven by the ipsilateral eye. Despite the decrease, the percentage of direction‐selective cells still was greater than in cats with an adult unilateral visual cortex lesion. Thus, while partly dependent on callosal inputs, some functional compensation for direction selectivity remains on the basis of ipsilateral inputs. In contrast, the percentage of cells driven by the ipsilateral eye was no longer significantly different from that in cats with an adult visual cortex lesion. This suggests that functional compensation for response to the ipsilateral eye is dependent on an intact corpus callosum in cats that received a visual cortex lesion at 8 weeks of age.
The organization and mutability of the forepaw and hindpaw representations in the somatosensory cortex of the neonatal rat
Authors: Dawson Douglas R. , Killackey Herbert P. 
Published: January 2005

AbstractThe present study demonstrates that the primary somatosensory cortex of the rat contains a map of the entire body surface that is discernible with a routine anatomical staining technique, the succinic dehydrogenase reaction. The overall proportions of this map are relatively constant from rat to rat and very similar to those reported in previous physiological investigations (Welker: Brain Res. 26:259–275, '71, J. Comp. Neurol. 166:173–190, '76). We found 67% of the map to be related to the head of the rat, 15% to the forelimb, 14% to the trunk, and 4% to the hindlimb. Within the forelimb and indlimb representations, there is a consistent internal organization that can be related to specific peripheral structures (digits or palm pads). Further, damage to either the periphery or the nerves innervating these regions on the day of birth produces disruptions in the normal pattern, but damage on day 6 or later does not. We interpret these results as indicating that the role of the periphery in organizing central neuronal structures during development previously demonstrated for the trigeminal system extends to the entire rat somatosensory system. Comparison of the present results with physiological studies of adult cortical maps after peripheral damage suggests to us that different substrates underlie the changes reported in the adult.
Forelimb motor cortical projections in normal rats and after neonatal hemicerebellectomy: An anatomical study based upon the axonal transport of WGA/HRP
Authors: O'Donoghue Daniel L. , Kartje‐Tillotson Gwendolyn , Castro Anthony J. 
Published: January 2005

AbstractCerebral cortical projections from the forelimb motor cortex, as defined by intracortical microstimulation where movements were evoked at low current intensities (< 15μA), were examined in normal rats and in adult rats that sustained neonatal hemicerebellectomy. The distribution pattern of cortical efferent projections in normal rats generally appeared more restricted than previously described. This restricted distribution is attributed to the use of WGA/HRP as the axonal tracing method and to the electro‐physiological definition of the injection site as the motor cortex. The observed remodeling of the corticobulbar projections, seen after cerebellar lesions in the young, largely confirmed previous reports. Moreover, no alterations in the laterality of distribution in corticospinal projection were found. Aberrant corticospinal projections were sought in an effort to provide an anatomical basis to a previous description of abnormally low‐threshold ipsilateral forelimb responses evoked from the motor cortex in adult rats after neonatal cerebellar lesions. This apparent absence of corticospinal tract remodeling after neonatal hemicerebellectomy suggests that the abnormal responses are mediated by the normal corticospinal pathways. This possibility is discussed in terms of an alteration in the spinal circuits that may change the responsiveness of spinal motoneurons to a given pyramidal discharge.
Sexual dimorphism in sympathetic preganglionic neurons of the rat hypogastric nerve
Authors: Nadklhaft Irving , McKenna Kevin E. 
Published: January 2005

AbstractHorseradish peroxidase (HRP) applied to one hypogastric nerve labelled sensory neurons in T11–L3 dorsal root ganglia (DRG) bilaterally and preganglionic neurons (PGN) in the spinal cord segments T13–L3. An average of 130 small DRG neurons were labelled per animal (male or female). These were concentrated in the L1 + L2 DRGs (92%). About 75% were located ipsilateral to the site of HRP application. Central projections from DRG neurons were noted throughout Lissauer's tract and in the marginal zones (medial and lateral) near the borders of Lissauer's tract. A short projection was also seen extending to the dorsolaterai funiculus.More than 90% of the preganglionic neurons were located in segments L1 + L2. Most of these were found in the dorsal commissural nucleus (75%) and most of the remainder were located bilaterally in the intermediolateral columns. Somewhat more intermediolateral neurons were labelled on the ipsilateral side than on the contralateral side. There were a few intercalating neurons and a very few funicular cells. An average of 415 PGNs were labelled in the male animals and 110 in the females, demonstrating a strong sexual dimorphism. No dimorphism was found in the sensory components.
Histochemical identification of pallidal and striatal structures in the lizard Gekko gecko: Evidence for compartmentalization
Authors: Russchen Fokje T. , Smeets Wilhelmus J. A. J. , Hoogland Piet V. 
Published: January 2005

AbstractThe present study provides a description of the distribution patterns of enkephalin, substance P and dopamine immunoreactivity, and acetylcholinesterase activity in the striatum, nucleus accumbens, globus pallidus, and ventral pallidum of the Gekko gecko. The pallidal structures were identified on the basis of characteristic enkephalin and substance P immunoreactive Plexus. The globus pallidus contains a very dense enkephalin immunoreactive wooly fiber plexus and a light and less extensive substance P immune‐reactive plexus. The ventral pallidum is characterized by substance P and enkephalin immunoreactive woolly fiber plexus, which show a dense and moderate staining, respectively. The striatum and the nucleus accumbens were found to be inhomogeneous with respect to staining intensities for all four makers. Except for the enkephalin immunoreactivity distribution pattern in the striatum, the compartments that can be distinguished in material stained for these markers appear to coincide quite well.
Development of the spinal nerves in the lamprey: III. Spinal ganglia and dorsal roots in 26‐day (13 mm) larvae
Authors: Nakao T. , Ishizawa A. 
Published: January 2005

AbstractSerial sections of the trunk and tail of 26‐day (13 mm) larval lampreys were examined by light and electron microscopy.Trunk region: Spinal ganglia and ventral nerves are seen alternately along the spinal cord and the notochord in the trunk. Spinal ganglia are located medially in intermyotome spaces with intersegmental blood vessels and send “dorsal nerves” ventrally along the vessels. “Ventral nerves” are seen on the midmedial surface of each myotome. Fibers containing densecored vesicles occur in the dorsal root but not in the ventral root.Caudal region: In the caudal one‐third of the tail the ventral nerves are formed earlier than spinal ganglia and dorsal nerves. The most caudal (primitive) ventral nerve (root) develops at the 12th myotome from the caudal end of the series of myotomes, the caudalmost ganglion being formed between the 15th and the 14th myotome in a 13‐mm larval lamprey. The intimate association of dorsolateral outflow (DLO) fibers (Nakao and Ishizawa: J. Comp. Neural 256:356–368, '87b) with neural crest cells (DO cells of Nakao and Ishizawa; ibid.) strongly suggested that these fibers play an important role as the substrate for guiding the cells to form compact cell masses as primitive spinal ganglia. Two types of cell groups are progressively distinguished in primitive spinal ganglia during development. One of them has a light round nucleus with a prominent nucleolus and a large amount of the perinuclear cytoplasm that contains abundant free ribosomes, rough endoplasmic reticulum (ER), numerous Golgi apparatuses, and dense bodies. Cells of the other type are characterized by a dense, flattened nucleus with a small amount of perinuclear cytoplasm that extends as a thin cytoplasmic sheet to surround cells of the other type as a whole, the basal lamina surrounding the whole cell mass. The former type is interpreted as neural cells and the latter satellite cells of the ganglion. Central processes of ganglionic neural cells are assumed to enter the spinal cord along DLO fibers by using them as a substrate to establish the dorsal root. Intersegmental blood vessels develop later than spinal ganglia and peripheral processes extend along the vessels.