bluuebunny/crossref_metadata_2025_split huggingface dataset:
Architecture and frontal cortical connections of the premotor cortex (area 6) in the rhesus monkey
Authors: Barbas H. , Pandya D. N. 
Published: January 2005

AbstractThe premotor cortex (area 6) has several architectonic sectors that can be delineated on the basis of cytoarchitectonic and myeloarchitectonic features. Area 6 may be broadly subdivided into a dorsal and a ventral sector at the spur of the arcuate sulcus. Dorsal 6 lacks a granular layer IV, but ventral 6 has an emergent layer IV that separates laminae III and V. Dorsal 6 has a higher myelin content than ventral 6. Dorsal area 6 is further subdivided into a caudal and a rostral sector on the basis of the presence of large pyramidal cells in the caudal but not in the rostral sector. The rostral sector of area 6 can be subdivided into a medial region distinguished from a more laterally situated area by the presence of more compact and darkly stained cells in layers III and V. Ventral area 6 can be subdivided into an upper and lower division. The upper part has more prominent pyramidal cells in layers III and V, and a better developed outer Baillarger band and vertical plexus than the lower division. The efferent and afferent connections of area 6 were studied with anterograde and retrograde tracers. The frontal connections of dorsal area 6 are restricted to neighboring dorsal frontal regions. Only the caudal sector of dorsal area 6 is connected with the motor cortex. In contrast, ventral area 6 is not only connected with the prefrontal cortex, but also directly with the motor cortex, the parainsular gustatory area, and with somatosensory areas in the frontal operculum. The widespread connections of ventral area 6 may be related to the specialization of the head, neck, and face structures that are represented ventrally within the premotor cortex.
Nerve growth factor (NGF) receptor expression in chicken cranial development
Authors: Raivich Gennadij , Zimmermann Astrid , Sutter Arne 
Published: January 2005

AbstractIn order to map the expression of receptors for nerve growth factor (NGF) during brain and cranial ganglia development, iodinated NGF (125IβNGF) was used as a probe in an autoradiographical analysis performed between embryonic day 3 (E3) and posthatching day 3 (P3) of chicken development. Heavy autoradiographic labelling was observed at the classical NGF target sites, the proximal cranial sensory ganglia and the sympathetic superior cervical ganglion, throughout development and after hatching. In contrast, only weak Labelling could be detected during a restricted time span in the vestibulocochlear (E4–E8) and the distal cranial sensory ganglia (E4–E10), the neurons of which originate from the otic and epibranchial placodes. Specific 125b̃3NGF binding was also observed in various brain regions during early brain development. NGF receptor expression there followed a characteristic pattern. The neuroepithelial layer displayed very low levels of specific 125Ib̃NGF binding, while strong 125Ib̃NGF labelling was found in the mantle layer. Brainstem somatomotor nuclei, visceromotor columns, brain‐stem alar plate, cerebellar anlage, tectum, and basal forebrain (epithalamus, striatum) were found to be transiently labelled by 125Ib̃NGF in early development (E4–E12). Non‐nervous tissues such as parts of the otic vesicle epithelium and skeletal muscle anlagen of the head were also labelled. These results, showing specific binding of 125Ib̃NGF to cranial cells of different origin (neural tube, neural crest, placode, and possibly mesoderm) strengthen the concept that NGF may have diverse functions in growth and differentiation of various tissues and cell types.
Plasticity of dendrodendritic microcircuits following mitral cell loss in the olfactory bulb of the murine mutant purkinje cell degeneration
Authors: Greek Charles A. , Halász Norbert 
Published: January 2005

AbstractMitral cells of the olfactory bulb typically form reciprocal dendrodendritic synapses with anaxonic interneurons, granule cells, within a sublamina of the external plexiform layer. As a result of mitral cell loss in the murine mutant Purkinjie cell degeneration (PCD), subpopulations of these granule cells are denervated. The present report examines the capacity of these denervated interneurons to form new dendrodendritic microcircuits with a second population of olfactory bulb neurons, tufted cells.Quantitative ultrastructural assessments were made of the morphology and distribution of dendrodendritic circuits in the olfactory bulbs of normal heterozygous litter mates and affected homozygous recessive PCD mice following mitral cell loss. There were no apparent morphological characteristics that distinguished the reciprocal synaptic connections formed by mitral cells from those formed by tufted cells. However, the segregation of mitral cell dendrodendritic circuits in the deep sublamina of the external plexiform layer (EPL) and tufted cell circuits in the superficial sublamina provided the basis for a comparative analysis of synaptic organization following mitral cell loss. Following mitral cell loss there was a significant reduction in the area occupied by characteristic mitral cell dendrites within the deep sublamina of the EPL. A slight but nonsignificant increase in the area occupied by granule cell spines was also observed. The number of synaptic appositions involving granule cells decreased slightly, the number involving tufted cells increased significantly in the mutant mice. This indicates that many granule cell spines survive denervation and establish new reciprocal dendrodendritic synapses at available sites on tufted cells. In both the control and mutant mice the ratios of symmetrical: asymmetrical dendrodendritic synapses closely approached 1. This demonstrates that not only do the denervated spines receive new afferent input from tufted cell dendrites, but they also establish the reciprocal efferent projection. These data are discussed in terms of the sublaminar organization of dendrodendritic microcircuits in the olfactory bulb and their capacity of plasticity and reorganization following pertubation.
Development of the spinal nerves in the lamprey: I. Rohon‐beard cells and interneurons
Authors: Nakao Taisuke , Ishizawa Akimitsu 
Published: January 2005

AbstractTwo types of large neurons are described in the caudal one‐third of the spinal cord of larval lampreys (26‐day, 13‐mm), Lampetra japonica.Rohon‐Beard cells (RB cells) are large neurons (8–14 m̈m in diameter) consistently positioned superficially in the dorsolateral part of the medullary wall and separated from the extramedullary space only by a basal lamina and a thin glia limitans and from the central canal lumen by the ependyma. The RB cell contains an extensive Golgi apparatus and granular endoplasmic reticulum. Its two processes arise from the basal part of the perikaryon and join the dorsolateral tract (DLT) to extend rostrally and caudally within the DLT, which is formed exclusively by contribution of RB cell processes at least in the caudal one‐third of the tail spinal cord. RB cells receive no synaptic nerve endings on their surfaces. The early developing RB cell exhibits an apical process that reaches the luminal surface of the central canal.Interneurons (15–19 m̈m in diameter) lie in the lateral region of the cord between the DLT and ependyma and receive from the DLT many synaptic nerve endings that contain aggregates of small, clear vesicles. They contribute axonal processes to the ventrolateral tract (VLT). Some developing interneurons have an apical process that contains abundant free ribosomes and granular ER.A presumptive model of how these cell classes are interconnected within the cord is presented.
The morphology of a population of thoracic intersegmental interneurones in the locust
Authors: Laurent Gilles 
Published: January 2005

AbstractA population of intersegmental interneurones with axons extending from the meso‐ to the metathoracic ganglion of the locust is described. They receive specific mechanosensory inputs from one mesothoracic leg. Their cell bodies are in group at the posterior of the mesothoracic ganglion, lying over the lateral base of each connective, and their primary neurites emerge in one of four bundles. Their mesothoracic branches are ipsilateral to the cell bodies and the leg from which they receive inputs. Each interneurone has two to six mesothoracic secondary neurites that divide and form a dense field of arborizations in specific regions of the neuropil so that each individual interneurone has a characteristic shape that is an elaboration of a basic and common plan.An interneurone excited by tibial campaniform sensilla and tarsal hair afferents branches in the intermediate neuropil and the ventral association center where the afferents from these receptors also project. An interneurone excited by proprioceptive inputs from the tarsus arborizes in the dorsal and intermediate neuropils, lateral to the ventral intermediate and ventral median tracts, in the same area as the proprioceptors afferents. An interneurone inhibited by proprioceptive inputs from the tibia (and wing) arborizes only in the dorsal neuropil, where there are no afferent projections.Some interneurones have one to three axonal branches with sparse and varicose side branches in the mesothoracic ganglion, which resemble the metathoracic axonal branches.The metathoracic axonal branches are mostly restricted to the dorsal neuropil and the dorsal part of the intermediate neuropil where local non‐spiking interneurones and motor neurones controlling movements of the hind leg also project.The overlap between the branches of the sensory afferents and the intersegmental interneurones in the mesothoracic ganglion and between those of the nonspiking local interneurones or motor neurones and intersegmental interneurones in the metathoracic ganglion suggest that these interneurones are responsible for transferring information about the action of one leg to an adjacent leg.
Transmitter localization and vesicle turnover at a serotoninergic synapse between identified leech neurons in culture
Authors: Kuffler Damien P. , Nicholls John , Drapeau Pierre 
Published: January 2005

Abstract
An electron microscopic study has been made of chemical synapses that develop between identified nerve cells isolated from the CNS of the leech and maintained in culture. Structures resembling synapses were observed in pairs of Retzius cells and P sensory cells at which chemical transmission had been demonstrated by recording with microelectrodes. Vesicle recycling was shown by following the uptake of extracellular markers after stimulation.
The membrane separation between the presynaptic Retzius cell (which is known to liberate serotonin) and the postsynaptic P cell was wider in synaptic than in extrasynaptic regions. The Retzius cell contained clusters of clear vesicles apposed to thickenings of the presynaptic membrane. These clear vesicle clusters were capped by a layer of dense core vesicles that did not contact the presynaptic membrane thickenings. Subsynaptic cisternae were found in the postsynaptic cell opposite the presynaptic membrane thickenings. Occasional slight postsynaptic membrane thickenings were seen. Extracellular material was observed within the synaptic cleft.
Similar synaptic structures developed between pairs of Retzius cells in culture; even a single Retzius cell was able to form autapses upon itself.
Structures resembling transmitter release sites were found in Retzius cells at a distance from any postsynaptic membranes. These are presumed to be locations for the diffuse release of transmitter.
Presynaptic structures resembling release sites were never observed in P cells apposed to Retzius cells.
Antibody to serotonin (5‐HT) labelled with colloidal gold showed serotonin to be localized in the dense core vesicles in Retzius cells.
Stimulation of pairs of Retzius and P cells by raised concentrations of K+ resulted in uptake of extracellular markers. Only Retzius cells became labelled. Ferritin was found in cisternae, in dense core vesicles, and in clear vesicles. HRP was found in cisternae and in clear vesicles. Colloidal gold was taken up by coated vesicles and was occasionally found in both clear and dense core vesicles. The uptake of extracellular markers following stimulation was blocked by high Mg ++.
These results show that structures develop between pairs of cells at which chemical transmission develops and that transmitter release leads to turnover of dense core and clear vesicles.
Time course and distribution of motoneuronal loss in the dorsal motor vagal nucleus of guinea pig after cervical vagotomy
Authors: Laiwand R. , Werman R. , Yarom Y. 
Published: January 2005

AbstractCells in the dorsal motor vagal nucleus (DMVN) of the adult guinea pig were counted at different times after unilateral cervical section of the vagus nerve. The counts were made from serial 30 μm coronal sections throughout the DMVN in normal and operated animals. There are three types of cells in the DMVN of guinea pig: medium‐sized motoneurons that are retrogradely filled by HRP from the site of the vagotomy, small neurons, and glial cells. An interesting observation was a change in distribution of cells in the DMVN with age in unoperated guinea pigs.Following vagotomy degeneration was seen only in the motoneurons. Disappearance of motoneurons was slow and only 27% were present after 1 year. During that time the decrease in the total number of motoneurons was exponential with a time constant of 8.6 months, but degeneration in different parts of the nucleus was not uniform. Thirty‐four percent of motoneurons in the caudal area of DMVN disappeared in the first month after vagotomy, while the rostral area was almost unchanged. The rostral area, however, showed rapid degeneration between 3 and 6 months after vagotomy. The central part of the nucleus degenerated at a constant rate between those of the rostral and caudal regions. At the end of 1 year, cell loss in all parts of the nucleus was approximately equal.Surviving motoneurons showed morphological changes: rounding of the soma, continuous reduction of the cell volume, and shrinkage of the nucleus. Occasional abnormal forms showing vacuolization or invaginated nuclei were seen. Calculations show that the process of degeneration lasts 25 days on the average.The marked degeneration found in dorsal vagal motoneurons, in contrast to recovery from axotomy in somatic motoneurons, is similar to that found in intrinsic neurons of the central nervous system. The slow and continuous time course of disappearance of motoneurons after vagotomy, however, is exceptional. It is reasonable to postulate that the increased vulnerability of these motoneurons may be sufficient to result in degeneration in response to what are normally nonpathological metabolic demands.
Specific neurotrophic interactions between cortical and subcortical visual structures in developing rat: in vivo studies
Authors: Haun Forrest , Cunningham Timothy J. 
Published: January 2005

AbstractThe specificity of trophic interactions in the rat visual system is investigated in vivo by using a combination of tissue culture and CNS transplantation methods. In a companion paper (Repka and Cunningham: '87) we showed that explants of embryonic day 14 (E14) occipital cortex are biased to contain different cortical cell populations depending on whether the explants develop in culture with diencephalon or with optic tectum. In this study we transplanted these precultured cortical explants into the cavity created by a lesion of the occipital cortex in newborn rats and then measured the neuron‐occupied volume and the numbers of thymidine‐labeled cells in the surviving ipsilateral dorsal lateral geniculate nucleus (dLGN) of the host rats. The results were compared to (1) animals with lesions but no transplants, (2) animals with transplants of E14 cortical tissue that had not been precultured, and (3) animals with cerebellar transplants that had been similarly precultured either with other cerebellar tissue or with diencephalon. At 5 days postlesion, both the largest dLGN volume and the greatest number of labeled dLGN neurons survive in animals with cortical transplants precultured with diencephalon or other cortex. The surviving dLGN neurons that are rescued by these transplants are generated on E15 or E16, a period that corresponds to the latter part of geniculate neurogenesis. Relatively few cells generated on E14 survive in any group of animals. Furthermore, animals with all types of cortical transplants have significantly larger volumes of surviving dLGN than animals with either leisons only or cerebellar transplants. However, by 9 days postlesion, the dLGN has almost completely disappeared in all groups of rats, indicating that the effect of the transplants is temporary. The results demonstrate that cortical transplants can protect host neurons in particular stages of development from degeneration after a cortical lesion and suggest that a particular population of later‐generated cortical cells is responsible for this effect. Since many of these later‐generated cells may represent neurons that are the natural targets of dLGN neurons, the results suggest a high degree of neurotrophic specificity during in vivo development of the rat visual system.
Opposing parallel connections through crayfish local nonspiking interneurons
Authors: Nagayama T. , Hisada M. 
Published: January 2005

AbstractUnilateral local nonspiking interneurons in the terminal (sixth) abdominal ganglion of crayfish (Procambarus clarkii Girard) can be classified into two major groups of PL and AL types by their gross morphology and somatic position. These premotor interneurons are the neural components of uropod motor pattern formation. They receive sensory input from the exopodite of the contralateral side as well as that of the ipsilateral side. Small fluctuations in their membrane potentials cause sustained change in activity of the motoneurons innervating the uropod muscles. PL interneurons, which make noninverting connections to an identified closer, the reductor motoneuron No. 1, mainly receive excitatory input from the afferents of the contralateral exopodite, whereas inverting PL interneurons receive inhibitory input. AL interneurons receive distinctly different input from the afferents. Noninverting AL interneurons mainly receive inhibitory input, whereas inverting AL interneurons receive excitatory input. The rate of discharge of the reductor motoneurons is increased by sensory stimulation. The PL interneurons form either excitatory or disinhibitory pathways, which are relevant in function to the observed increase of the motoneuron. Conversely, the AL interneurons form either inhibitory or disfacilitatory pathways. Thus, the PL and the AL interneurons are fractionated in function and distinguishable in terms of their physiology by their input and output correlations. Functional meaning of the presence of these two types of unilateral local nonspiking interneurons of opposing connections in the uropod motor control system is discussed.
Effect of prenatal exposure to alcohol on the distribution and time of origin of corticospinal neurons in the rat
Authors: Miller Michael W. 
Published: January 2005

AbstractThe distribution and the time of origin of corticospinal neurons were examined in rats prenatally exposed to ethanol and in control rats. The distribution of corticospinal neurons was determined by tracing the retrograde transport of horseradish peroxidase (HRP) from an injection site in the cervical spinal cord.In control rats, HRP‐positive neurons were distributed in layer Vb throughout motor area 4, rostral motor area 6/8, dorsal somatosensory area 3, caudal somatosensory area 2, and various “association” regions including parietal areas 14, 39, and 40, occipital areas 18a and 18b, cingulate areas 24a and 24b, and prefrontal area 32. In ethanol‐exposed rats, the distribution of retrogradely labeled neurons was similar to control animals with three notable exceptions: (1) HRP‐positive neurons were evident throughout the rostrocaudal extent of area 6/8; (2) occasionally ectopic labeled neurons were identified in the supragranular layers, layers Va and Vc, and superficial layer VI; and (3) the density of HRP‐labeled neurons and the ratio of labeled neurons to the total number of neurons in areas 4, 6/8, 3, and 2 were significantly greater (20–48%) in ethanol‐exposed rats than in controls. There was, however, no intergroup difference in the area of the cell bodies of HRP‐positive neurons. Taken together, these findings indicate that ethanol exposure resulted in an increased number of corticospinal neurons.The time of origin of corticospinal neurons was determined by using a technique that combined tritiated thymidine autoradiography and retrograde transport of HRP. In control animals, HRP‐positive neurons were double labeled by an injection of tritiated thymidine on gestational day (GD) 15, 16, or 17. In ethanol‐exposed rats, corticospinal neurons were generated on GD 16, 17, and 18, the late‐generated ones being distributed in caudal area 6/8.These intergroup differences represent a persisting ethanol‐induced alteration of cortical structure that may underlie motor dysfunction and mental retardation in fetal alcohol‐affected offspring. Moreover, the increase in the number and the delay in the time of origin of corticospinal neurons suggest that the normal process of paring down exuberant orticospinal projections may be affected by prenatal exposure to ethanol.
Thalamic connectivity of the primary motor cortex of normal and reeler mutant mice
Authors: Terashima Toshio , Inoue Kaoru , Inoue Yoshiro , Mikoshiba Katsuhiko 
Published: January 2005

AbstractReeler, an autosomal recessive mutation in mice, causes cytoarchitectonic abnormalities of the cerebral cortex, which are characterized by malposition of neurons. Retrograde and anterograde transport of horseradish peroxidase (HRP) was employed to examine the reciprocal connectivity between the hindlimb area of the primary motor cortex (MI) and thalamus of normal and reeler mutant mice. In the normal mouse, most of the cells labelled after HRP injection into the hindlimb area of MI were located in the ventrolateral nucleus, the lateral division of the ventrobasal nucleus, the central lateral, paracentral and central intralaminar nuclei, and the medial division of the posterior complex. HRP reaction product antero‐gradely transported was also observed in the same nuclei and in the thalamic reticular nucleus. In the reeler mutant mouse, retrogradely labelled neurons and anterogradely labelled terminals were again found in the nuclei referred to above, and the distribution pattern and morphology of HRP‐filled neurons were also similar to those of normal controls. The present results suggest therefore that the normal reciprocal connectivity between MI (hindlimb representation) and thalamus is preserved in the reeler mouse. That is to say, dislocated cortical neurons appropriately project to their target nuclei of the thalamus, and conversely, thalamic neurons send their axons precisely to their target cortical areas of the radially disorganized cortex.