bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential origins of spinothalamic tract projections to medial and lateral thalamus in the rat
Authors: Giesler Glenn J. , Menétrey Daniel , Basbaum Allan I. 
Published: January 2005

AbstractIn an earlier study (Giesler et al., 1976), antidromically identified cells of origin of the rat spinothalamic tract (STT) were found to be widely distributed throughout the lumbar dorsal horn and intermediate gray zone (IGZ). Interestingly, it appeared that STT neurons located within the ventral dorsal horn and IGZ, which appeared to respond to stimuli delivered to subcutaneous tissue, tended to be activated only from midline thalamic structures. In contrast, STT neurons within nucleus proprius and the marginal zone, which responded to noxious and innocuous cutaneous stimuli, were activated from lateral thalamic structures. The present study has investigated this apparent dichotomy in thalamic afferents using the technique of retrograde transport of horseradish peroxidase (HRP).Single and multiple small injections of HRP were made in various thalamic regions. Tissue was reacted with diaminobenzidine (DAB) or o‐dianisidine (OD). Our data provide evidence that DAB histochemistry yields a more accurate reflection of the HRP concentrations surrounding an injection site which are necessary for visible retrograde transport. On the other hand, OD was found to be the more useful technique for examining labeled spinal cord neurons. With this method, 3 to 5.3 times more STT neurons were seen and far greater morphological detail was evident.Multiple HRP infusions which filled an entire hemi‐thalamus labeled large numbers of cells within the spinal extensions of the dorsal column nuclei, the lateral cervical nucleus, the ventral horns and IGZ bilaterally within C1 and C2, and the nucleus proprius and IGZ at all levels. STT neurons were also seen, but in lesser numbers within the marginal zone. Labeling in spinal segments below C3 was, with a single exception, exclusively contralateral. The lumbar enlargement was seen to contribute a greater number of STT neurons than the cervical enlargement. Injections into posterior medial thalamic structures produced bilateral labeling in the ventral horns and IGZ in upper cervical segments. Within the cervical and lumbar enlargements, labeled neurons were restricted to ventral dorsal horn and to IGZ contralaterally. With the exception of the ventral horn cells of C1 and C2 where a marked reduction in labeling occurred, more anterior medial thalamic injections produced labeling within the identical areas of the gray matter and in numbers comparable to those produced by more posterior medial thalamic injections. In contrast, injections into lateral thalamic areas yielded dense labeling within the caudal extensions of the dorsal column nuclei and lateral cervical nucleus. Labeled cells were seen in the marginal zone and nucleus proprius at all levels.Together with our earlier findings, these data suggest that the rat STT is composed of two components which vary in their cells of origin, their terminations and, very likely, their functions.
Modification of neuron numbers in the visual system of the rat
Authors: Cunningham Timothy J. , Huddelston Chris , Murray Marion 
Published: January 2005

AbstractAfter unilateral lesions of the posterior cerebral cortex at birth, the ipsilateral dorsal lateral geniculate nucleus disappears within 96 hours. Several of the remaining visual centers may be distorted, atrophic or hypertrophic. Examples of the last are the ipsilateral nucleus of the optic tract (NOT) and superficial layers of the superior colliculus (SC), which usually show a volume increase. In order to determine changes in neuron numbers in these two regions, we exposed rats to 3H‐thymidine on specific embryonic days. Some of these rats received posterior cortical lesions on the day of birth and others served as controls. Counts from adult rats exposed to 3H‐thymidine on embryonic days 13 and 14 reveal a significant increase in the number of labeled neurons in both the NOT and SC on the side of the lesion. The retinal projections in rats with posterior lesions at birth were determined by the application of silver degeneration methods after eye removal. Atypical optic projections are found to the lateral posterior nucleus and the NOT on the side of the lesion. We conclude that the redistribution of optic collaterals after early destruction of the dorsal lateral geniculate nucleus serves to increase neuron numbers in the NOT and SC. Therefore, the present findings are comparable to the results in nonmammals after transplantation of additional peripheral organs.
Somatic neurons in the brainstem and neocortex projecting to the external nucleus of the inferior colliculus: An anatomical study in the opossum
Authors: Robards Martine J. 
Published: January 2005

AbstractSome brainstem and neocortical neurons projecting to the external nucleus of the inferior colliculus were identified by retrograde axonal transport of horseradish peroxidase (HRP). Large pressure injections of HRP were used to define the population of cells in the dorsal column and trigeminal nuclei projecting to the entire inferior colliculus. Subsequently, tiny injections of HRP were delivered electrophoretically to various parts of the external nucleus using micropipettes. In each case the electrophoretic placements were made in sites identified as somatic by their response to foot shock or manual stimulation of the body. Receptive fields were found to be large and almost always bilaterally symmetric. Areas excitable by stimulation of the upper body were often found adjacent to areas excitable by stimulation of the lower body, tail, or, rarely, the face and head. In general, sites in the external nucleus which were identified by their responsiveness to stimulation of the body were not responsive to click stimuli. No topographic representation of the body was evident. After small electrophoretic injections of HRP absolutely restricted to the external nucleus, HRP‐filled neurons were found bilaterally in the nucleus gracilis, nucleus Bischoff, (the midline and tail representation of the dorsal column nuclei), nucleus cuneatus, and nucleus trigeminalis, subnucleus caudalis. Ipsilateral neocortical cellular filling was found primarily in a continuous strip along the caudal and inferior margin of the parietotemporal cortex, in the area corresponding to SMII (Pubols, '77). Rarely, filled cells were found in the parietal area corresponding to SMI and in the temporal pole. In sum, small somaticactivated loci of the external nucleus receive bilateral, topographically convergent projections from hindbrain somatosensory structures and from the SMII cortex.
Commissural and intrinsic connections of the rat hippocampus
Authors: Laurberg S. 
Published: January 2005

AbstractThe commissural and intrinsic connections of the hippocampus were studied using the Fink‐Heimer method and the horseradish peroxidase (HRP) uptake technique.A conspicuous septo‐temporal gradient was found of the density of the commissural projection that passes through the psalterium ventrale to the Ammon's horn. The degeneration resulting from transection of the psalterium ventrale was most dense in the septal tip and decreased towards the temporal tip. The commissural and ipsilateral connections from the hilus fasciae dentatae (CA4) and regio inferior (CA3/CA2) were found to terminate in different parts of the hippocampus. The hilus fasciae dentatae gave rise to ipsilateral and commissural projections to the dentate area only. The regio inferior has ipsilateral and commissural projections to the Ammon's horn.A specific termination pattern was found of the projection from regio inferior to stratum radiatum of both the ipsilateral and contralateral regio superior (CA1) and regio inferior (CA2/CA3). At levels temporal to the lesion, the projection is primarily to the superficial part of stratum radiatum, while at levels septal to the lesion the terminal zone occupies the deep part of the layer. This pattern was not related to the position of the cells of origin, along the septotemporal or subiculo‐dentate axes.In general, the commissural projections showed the same degree of septotemporal divergence as the ipsilateral projections. The only major difference in the terminal fields of the two sets of projections to the Ammon's horn was that the terminal zone of the commissural projection to stratum oriens was always more dense than that of the ipsilateral projection to this layer, while an inverse gradient was seen in stratum radiatum.The projections from the septal and middle dorso‐ventral parts of regio inferior differed. The temporal spread of the projections from the septal part was large while that from the projections arising at middle dorso‐ventral levels was more restricted. Moreover, a longitudinal association path interconnecting different parts of the regio inferior along the septo‐temporal axis was seen to arise only from the cells in the septal parts of the regio inferior.Each part of the regio inferior projected to all parts of stratum radiatum and oriens of the contralateral Ammon's horn. However, the projection to the contralateral regio inferior was most dense at the site homotopic to that lesioned. The ventricular part of regio inferior projected primarily to the contralateral stratum oriens of the Ammon's horn, while the part adjacent to the dentate area mostly supplied stratum radiatum.
Behavioral and electrophysiological effects of unilateral optic tract section in ordinary and siamese cats
Authors: Antonini A. , Berlucchi G. , Marzi C. A. , Sprague J. M. 
Published: January 2005

AbstractIn ordinary cats section of one optic tract produced a complete contralateral hemianopsia in both eyes. Single‐unit recordings showed a normal representation of the contralateral nasal retina and ipsilateral temporal retina in the SC on the side of the intact optic tract. In addition, in the rostral portion of this SC there was a representation of a small portion of the contralateral temporal retina. This portion was apposed to the vertical meridian and its width was at most 6°. In the anterior half of the SC on the side of the optic tract section, despite the interruption of any direct optic input, there was an extensive representation of the ipsilateral nasal retina and the contralateral temporal retina. This indirect visual input to the SC ipsilateral to the optic tract section was absent in a cat with a section of the forebrain commissures.In Boston Siamese cats, section of one optic tract led to a virtually complete blindness in the eye contralateral to the section, whereas the other eye retained a full visual field, although the responsiveness of the temporal retina beyond 20° from the vertical meridian was reduced. Similarly, the nasal hemiretina and most of the temporal hemiretina on the side of the section were represented in the opposite SC, whereas stimulation of the eye contralateral to the section could not drive SC units. There was some evidence that the visual field of the eye on the side of the section could at least in part be represented in the SC on the same side. The findings indicate that the crossed projections from temporal hemiretina in the ordinary cat, and the uncrossed projections from temporal hemiretina in the Siamese cat are insufficient by themselves to sustain visual orientation and to drive SC neurons. Each half of the visual field in the ordinary cat, and the field of each eye in the Siamese cat, can be represented in the ipsilateral SC via across‐the‐midline, indirect connections.
Fine structural analysis of the cortico‐striatal pathway
Authors: Hattori T. , McGeer E. G. , McGeer P. L. 
Published: January 2005

AbstractConsiderable evidence has accumulated indicating that one neurotransmitter in the excitatory cortico‐striatal tract is glutamate. Lesions of the tract result in reductions in the striatum of glutamate levels as well as high affinity uptake of glutamate into synaptosomes. Furthermore, such lesions leminate the neurotoxicity of the glutamate analog kainic acid when injected into the striatum. The fine structure of the cortico‐striatal pathway was studied to provide evidence regarding the morphology of glutamate nerve endings.Seven days after injection of 3H‐proline (20–25 μCi) into the rat frontal cortex, axonally transported label appeared in the striatum with uniform distribution in a single type of nerve ending. The labeled boutons had common round vesicles and made asymmetrical contacts, mostly with dendritic spines. This morphology is typical of excitatory synapses, and similar to that previously shown for cholinergic boutons in the striatum.In four animals similarly injected with 3H‐proline, kainic acid was administered directly into the striatum to induce degeneration of postsynaptic elements eight to ten hours before sacrifice. In areas affected by these injections, grains appear in pathches, possibly resulting from glial swelling. Labeled boutons were seen almost four times as often in synaptic contact with degenerating dendritic elements as with normal ones. The data provide morphological evidence as to the nature of the probable glutamatergic boutons in the striatum, and show the close relationship of such boutons with the neurotoxic effects of kainic acid. This would be anticipated in view of the dependency of kainic acid neurotoxicity on the intergrity of the cortico‐striatal pathway.
A quantitative study of lipofuscin accumulation with age in normals and individuals with Down's syndrome, phenylketonuria, progeria and transneuronal atrophy
Authors: West Christopher D. 
Published: January 2005

AbstractThe amount of lipofuscin in neurons of two brainstem nuclei, the inferior olivary nucleus (ION) and the lateral geniculate nucleus (LGN), was measured in the brains of 1 progeric, 2 phenylketonuric, 5 Down's syndrome and 13 normal individuals. Aggregations of lipofuscin granules in cresyl violet stained sections were examined with epi‐fluorescent illumination, drawn with a camera lucida, and measured with a planimeter. The proportion of lipofuscin to cell size was a linear function of age over the age range examined, 14 to 92 years. There was no difference between progeric, phenylketonuric, Down's and normal brains in the amount of lipofuscin accumulated with age, nor was there a marked within‐individual correlation between amounts of lipofuscin in the two nuclei when these amounts were subtracted from the regression line values to control for age. The proportion of lipofuscin to cell size was the same in neurons of the LGN showing transneuronal atrophy in response to right eye pathology as it was in non‐atrophic neurons.
Reexamination of the dorsal root projection to the spinal dorsal horn including observations on the differential termination of coarse and fine fibers
Authors: Light A. R. , Perl E. R. 
Published: January 2005

AbstractPrimary afferent fibers in the lumbar, sacral, and caudal spinal segments of several mammals (rat, cat, monkey) were stained by applying horseradish peroxidase to the proximal part of cut dorsal rootlets and reacting the tissue histochemically after several hours of survival. The stained fibers' pattern of termination in the dorsal horn was similar in all three species, with many bouton‐like enlargements in the ipsilateral marginal zone, substantia gelatinosa, and nucleus proprius, as well as a few projections at each level to the dorsal commissure and contralaterally to the ventral border of the nucleus proprius. Partial lesions of dorsal rootlets in monkey revealed that the thin fibers comprising the lateral division end principally in the marginal zone and substantia gelatinosa, while the thick fibers of the medial division terminate in the nucleus proprius and deeper regions, contributing little to the substantia gelatinosa and marginal zone. On the basis of the termination patterns observed for whole and partly sectioned rootlets, the superficial dorsal horn can be divided into at least four regions. (1) The marginal zone (lamina I of cat) appears to receive terminations from intermediate (smaller myelinated) fibers; (2) the outer substantia gelatinosa (outer lamina II) receives many terminations from the very finest afferent fibers; (3) the inner substantia gelatinosa (inner lamina II) receives endings from some of the finest fibers and also from intermediate (smaller myelinated) fibers; and (4) the superficial part of the nucleus proprius (lamina III) receives endings from intermediate and large diameter dorsal root fibers.
Trajectory of group Ia afferent fibers stained with horseradish peroxidase in the lumbosacral spinal cord of the cat: Three dimensional reconstructions from serial sections
Authors: Ishizuka Norio , Mannen Hajime , Hongo Toshinori , Sasaki Shigeto 
Published: January 2005

AbstractA reconstruction was made of the intramedullary trajectory of 23 physiologically identified Ia afferents from cat hind limb muscles (medial gastrocnemius, soleus, plantaris, flexor digitorum‐hallucis longus, and hamstring). The afferents were stained by intra‐axonally injected HRP. The axons of these afferents were traced over distances of 5.8 mm to 15.7 mm rostrocaudally. In the dorsal funiculus fibers from all the muscles showed a similar course and similarly bifurcated into an ascending and a descending branch. The mean diameters of stem axons, ascending branches, and descending branches were 6.6 μm, 5.8 μm, and 3.0 μm, respectively. Within the analyzed lengths of the spinal cord five to eleven collaterals were given off from the two branches. The distances between adjacent collaterals of the ascending and descending branches averaged 1200 μm and 790 μm, respectively.The collaterals as a rule passed through the medial half of the dorsal horn before they entered the deeper parts of the gray matter. The terminal distribution areas common to all Ia collaterals were: (1) the medial half of the base of the dorsal horn, mainly lamina VI; (2) lamina VII; and (3) lamina IX. The numbers of terminals were largest in lamina IX and smallest in lamina VII. The density of terminals in lamina IX was highest in the homonymous motor cell column. The terminal distribution areas of adjacent collaterals showed no overlap in the sagittal plane. Terminal branches carried one bouton terminal and up to six boutons en passage with an average of 1.8 terminals per terminal branch. Apparent axosomatic and axodendritic contacts were seen on small‐sized and medium‐sized neurons in laminae V–VI, medium‐sized neurons in lamina VII, and large neurons in lamina IX. One motoneuron was contacted by an average of 3.3 terminals.In addition to the common features, Ia collaterals of various muscles of origin showed some differences in their trajectories in the ventral horn, and in their terminations in the gray matter.
Alpha‐ and gamma‐motoneurons in the adult human spinal cord and somatic cranial nerve nuclei: The significance of dendroarchitectonics studied by the Golgi method
Authors: Abdel‐Maguid Thoraya E. , Bowsher David 
Published: January 2005

AbstractA modified Golgi method (Vaisamruat and Hess, '53) was found to give satisfactory impregnation of cell bodies and dendrites, but not of dendritic spines and axons, in adult human material fixed by immersion in formalin. Examination of the motor columns in the spinal cord intumescences and of the third and twelfth cranial nerve nuclei revealed four neuron types, based on dendritic field size and dendritic branching pattern. Two of these were recognized as alpha‐motoneurons; one of them was seen only in the medial motor column of the spinal ventral horn, while the other was observed in the cranial motor nuclei as well as the spinal lateral motor column. Differences in somadendritic dimensions in this neuron type were thought to reflect motor unit size, and thus terminal axon field dimensions. Of the two types of gamma‐motoneurons recognized in the spinal cord and oculomotor nucleus, one was a miniature version of the commoner type of alpha‐motoneuron. On this basis, it is proposed that it may give rise to fusimotor axons with plate endings. The second type of gamma‐motoneuron does not resemble any of the other motoneuron types, and its axons may therefore be thought to terminate in trail endings.
Cerebellar corticonuclear fibers of the dorsal culminate lobule (anterior lobe—lobule V) in a prosimian primate, Galago senegalensis
Authors: Haines D. E. , Rubertone J. A. 
Published: January 2005

AbstractThe organization of corticonuclear fibers from lobule V of the anterior lobe of the lesser bushbaby, Galago senegalensis, was studied utilizing the Fink and Heimer ('67) method. Corticonuclear fibers of lobule V are ipsilateral, topographically arranged in their trajectory into the deep cerebellar nuclei and organized into six identifiable zones. No evidence is seen to support the contention that these fibers may project diffusely into the cerebellar nuclei, either in a rostro‐caudal or medio‐lateral sequence, or that they may project to any of the contralateral nuclei.Lesions in lateral lobule V cortex produce degeneration in rostroventral magnocellular NL. No debris is seen in parvicellular NL and no degenerated axons enter the NIA, NIP or NM. The terminal field in the NL is roughly pyramid shaped with the base being located at the periphery of the nucleus and the apex directed toward the hilus. Based on the totality of its efferent projections the intermediate cortex (IC) of lobule V is a relatively wide region which is divisible into three separate areas. Lateral portions of the IC project heavily into the lateral NIA and send a sparse number of fibers into the NIP. The middle area of the IC sends fibers almost exclusively to a bifid terminal field located in the NIP. From this area of cortex no degenerated fibers enter either the NL or NM and only extremely sparse amounts of debris are seen in rostrolateral NIA. Following damage to medial regions of IC degeneration is seen primarily in medial portions of the NIA and in the juxtarestiform body, if the lesion involves the lateral portions of the vermal cortex. These three regions of the IC, identified here based on the arrangement of their corticonuclear fibers, represent the cortical correlates of compartments C1, C2 and C3 (of Voogd, '69). Lesions involving the lateral aspect of the vermal cortex produce degeneration in the vestibular complex, primarily its lateral nucleus, and in the NIP. These observations may represent a subdivision of this area, a fact previously reported in the cat (Oscarsson and Sjölund, '77a). The medial portions of the vermal cortex project primarily to rostrodorsal NM.The results of this study provide data concerning the arrangement of zones in the anterior lobe cortex of a primate. Due to the fact that differential projections into magnocellular versus parvicellular NL were not seen, the lateral cortex is designated only as zone D. The IC contains, from lateral to medial, zones C3, C2 and C1. The lateral edge of the vermal cortex is designated zone B, although it is recognized that subdivisions of this area may exist (Oscarsson and Sjölund, '77a) while zone A is the more medial area of vermal cortex. These zone designations represent those portions of cortex which overlie previously identified compartments (Voogd, '69) in the subcortical white matter.