bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lamination and differential distribution of thalamic afferents within the sensory‐motor cortex of the squirrel monkey
Authors: Jones E. G. 
Published: January 2005

AbstractThe structure of the first somatic sensory area (areas 3,1 and 2), of the motor area (area 4) and the intervening transitional field (area 3a) is described in the squirrel monkey (Saimiri sciureus) using Nissl, Bodian, Weil and Golgi preparations. The laminar arrangement of both cells and axons is briefly described and this is correlated with the Nauta and autoradiographic techniques. The latter method was used particularly in order to assess quantitative differences in the density of thalamic projections to the five cytoarchitectonic fields.In the somatic sensory areas thalamic afferents terminate not only in layer IV but to a large extent also in a recognizable part of layer III (layer IIIb). In area 4 thalamic terminals fill much of layer III, reaching almost to layer II. In area 3a the extent is intermediate between that seen in areas 3 and 4. It is thought that the extensive spread of thalamic terminals is related to the elongated form of a particular class of spine‐bearing cell whose somata are situated in layer IV (Jones, 1975). In all areas a small proportion of thalamic afferents end also in layer I. Evidence is presented to indicate that specific afferent fibers emanating from the ventrobasal and ventrolateral complexes of the thalamus terminate in both the deep and superficial parts of layer I While “non‐specific” afferents from other thalamic sources end in the superficial part.The autoradiographic studies indicate that there are considerable differences between the number of thalamic afferents ending in area 3 on the hand and in areas 1 and 2 on the other. Given this and the nature of the degenerating thalamic afferents observed in Nauta preparations, it is possible to identify thalamic afferents in normal Golgi preparations and significant differences are detectable in areas 4, 3 and 1 and 2. It is yet uncertain whether the slightly thinner, more sparsely distributed thalamic afferents ending in areas 1 and 2 are branches of those directed primarily to area 3.
Receptive fields of single cells and topography in mouse visual cortex
Authors: Dräger Ursula C. 
Published: January 2005

AbstractThe visual cortex was studied in the mouse (C57 Black/6J strain) by recording from single units, and a topographic map of the visual field was constructed. Forty‐five percent of the neurons in striate cortex responded best to oriented line stimuli moving over their receptive fields; they were classified as simple (17%), complex (25%) and hypercomplex (3%). Of all preferred orientations horizontal was most common. Fifty‐five percent of receptive fields were cicularly symmetric: these were on‐center (25%), off‐center (7%) and homogeneous on‐off in type (23%). Optimal stimulus velocities were much higher than those reported in the cat, mostly varying between 20° and 300°/sec. The field of vision common to the two eyes projected to more than one‐third of the striate cortex. Although the contralateral eye provided the dominating influence on cells in this binocular area, more than two‐thirds of cells could also be driven through the ipsilateral eye. The topography of area 17 was similar to that found in other mammals: the upper visual field projected posteriorly, the most nasal part mapped onto the lateral border. Here the projection did not end at the vertical meridian passing through the animal's long axis, but proceeded for at least 10° into the ipsilateral hemifield of vision, so that at least 20° of visual field were represented in both hemispheres. The magnification in area 17 was rather uniform throughout the visual field. In an area latral to area 17 (18a) the fields were projected in condensed mirror image fashion with respect to the arrangement of area 17. Medial to area 17 a third visual area (area 18) was again related to 17 as a condensed mirror image.
On the “selectivity” of the Golgi‐Cox method
Authors: Pasternak Joseph F. , Woolsey Thomas A. 
Published: January 2005

AbstractThe randomness of the impregnation of layer IV cortical neurons by the Golgi‐Cox method (Van der Loos, 1956) has been assessed directly in Barrel C‐1 of the mouse SmI. All Golgi‐Cox impregnated neurons and unimpregnated neurons which were revealed with Nissl counterstain were counted and measured in ten cerebral hemispheres cut tangential to the pia overlying the barrel field. The percentage of Golgi stained neurons varied considerably in different preparations from 0.73% to 2.26% with an average of 1.29%. The size distributions of both the Golgi impregnated and Nissl stained cells are similar but the difference of the means is statistically significant. However, if the means are eqated there is no statistical difference in the two populations. When the Golgi precipitate is removed and the cells re‐measured following Nissl staining there is a systematic reduction of the perikaryal cross‐sectional area which is compatible with the differences in the means observed for the two populations as a whole. Finally, the frequency with which Golgi impregnated neurons are found in the barrel sides and hollows parallels the frequency with which Nissl stained neurons are observed in these two locations. We conclude that this variant of the Golgi method impregnates barrel neurons randomly. The value of this information for quantitative studies of cerebral cortex is discussed as is the potential of the system for elucidating some of the mechanisms responsible for Golgi impregnation.
Intensity and pattern discrimination after lesions of the pretectal complex, accessory optic nucleus and ventral geniculate in pigeons
Authors: Hodos William , Bonbright James C. 
Published: January 2005

AbstractPigeons were trained to discriminate between pairs of visual stimuli that differed in intensity or pattern. After completion of traianing, bilateral, stereotaxic lesions were made in various cell groups in the mesencephalon and diencephalon that receive terminals of the optic tract. The target regions were nucleus ectomamillaris (accessory optic nucleus), nucleus lentiformis mesencephali and area pretectalis (pretectal complex) and the nucleus geniculatus lateralis, pars ventralis (ventral geniculate). In some cases, combined lesions of nucleus lentiformis mesencephali and area pretectalis were made. Lesions of nucleus ectomamillaris, nucleus lentiformis mesencephali, area pretectalis, or ventral geniculate did not produce major impairments of discrimination performance nor did combined lesions of nucleus lentiformis mesencephali and area pretectalis.A number of cases of intended destruction of the ventral geniculate also had extensive damage to the overlying nucleus rotundus. In several of these cases of combined destruction of nucleus rotundus and ventral geniculate, the previously reported discrimination deficits following nucleus rotundus lesions did not appear. In those cases in which the nucleus rotundus deficit was observed, the lesions were found to include the nucleus subpretectalis, which, like nucleus rotundus, receives tectofugal fibers via the brachium of the superior colliculus. The data of the ventral geniculate + rotundus cases and ventral geniculate + rotundus + subpretectalis cases suggest that sensory deficits following a lesion in a particular cell group may not necessarily indicate that the sensory information is processed in that cell group, but rather that the lesion had deprived other cell groups of the appropriate input necessary for their proper functioning.
Degeneration and phagocytosis of synaptic endings and axons in the medial trapezoid nucleus of the cat
Authors: Morest D. Kent , Jean‐Baptiste Michel 
Published: January 2005

AbstractThis study deals with the fine structure of the degenerative changes in the axonal calyces of the medial trapezoid nucleus after destruction of their cell bodies of origin in the contralateral cochlear nucleus. Two to four days after such lesions the main calycine processes which normally contain a core of neurofilaments, show a marked hyperplasia of neurofilaments, shrinkage, decrease in number of microtubules and mitochondria, swelling and decrease in number of synaptic vesicles, and the appearance of vesicular debris and coated vesicles. After seven days all of the calyces have degenerated. They are replaced by extracellular accumulations of neurofilaments, surrounded by phagocytic processes of proliferating astroglia and microglia. In contrast, the calycine appendages exhibit a dense mode of degeneration. Thus the different kinds of endings, arising from the very same fibers and synapsing on the very same cell bodies, exhibit two entirely different modes of degeneration. There is a correlation between the normal cytological features of the endings and their modes of degeneration. The preterminal calycine axons undergo filamentous hyperplasia in early degeneration.The observations indicate that both microglia and astroglia may participate in phagocytosis of the preterminal fibers and their endings and that astrocytes undergo mitosis. The microglia in electron micrographs correspond to the classical microglial cells that appear in perivascular locations in Golgi preparations. The disintegration of the calyces is accompanied by mutual invaginations of thin axonal and glial processes, followed by the disappearance of the axolemma. Extracellular break‐up appears to be a regular feature of this process, which may involve the intercellular transfer of soluble breakdown products by calycine and glial vesicles and uptake by tubular elements of the smooth endoplasmic reticulum in the phagocytes. Incisures of Schmidt‐Lanterman occur in the large calyciferous fibers; these fibers are often invaded by phagocytes before the myelin sheath degenerates.
Demonstration of a pallido‐nigral projection innervating dopaminergic neurons
Authors: Hattori T. , Fibiger H. C. , McGeer P. L. 
Published: January 2005

AbstractAfferents to the substantia nigra from the neostriatum and globus pallidus were studied in the rat by means of the autoradiographic tracing technique. 3H‐leucine was injected stereotaxically into either the globus pallidus or neostriatum. Twenty‐four hours later the axoplasmic transport of labelled proteins to the substantia nigra was studied by light and electron microscopic autoradiography. In animals used for electron microscopy, degeneration of dopaminergic cells in the substantia nigra was induced by intraventricular injection of 6‐hydroxydopamine 72 hours before sacrifice.After neostriatal injections, light microscopic analysis revealed heavy labelling of the globus pallidus and entopeduncular nucleus, but only background labelling of the subthalamic nucleus. There was preferential labelling of the zona reticulata of the substantia nigra, with significantly less labelling of the zona compacta.After pallidal injections, light microscopic analysis showed very light labelling of those parts of the caudate‐putamen in the vicinity of the injection site. There was intense labelling of the subthalamic nucleus and heavy labelling of the entopeduncular nucleus. The zona compacta of the substantia nigra was also heavily labelled. There was considerably less labelling of the zona reticulata.The electron microscopic analyses showed that after neostriatal injections, autoradiographic grains in the substantia nigra were located preferentially over boutons which terminated on normal dendritic processes. After pallidal injections, however, grains were preferentially located over boutons synapsing with degenerating dendritic processes. The degeneration produced in these dopaminergic processes by 6‐hydroxydopamine was invariably of the dark type. Except for the different association with degenerating vs. non‐degenerating dendrites, the subcellular distribution of autoradiographic grains in the substantia nigra was the same after injection into either the globus pallidus or caudate‐putamen. Approximately 80 percent of the grains were over axons or boutons which invariably made symmetrical synaptic contacts.These observations demonstrate the existence of a pallido‐nigral projection which terminates preferentially on dopaminergic cells in the pars compacta of the substantia nigra. They also confirm previous studies indicating that the strionigral projection terminates mainly in the pars reticulata. These terminations appear to be principally to non‐dopaminergic cells.
Implications of genetic variation in mouse brain structure for electrode placement by stereotaxic surgery
Authors: Wahlsten Douglas , Hudspeth William J. , Bernhardt Kathryn 
Published: January 2005

AbstractThe spatial locations of several forebrain and midbrain fibre tracts have been compared across seven commonly used inbred, hybrid and outbred mouse strains using a series of electrolytic lesions of known postitions with respect to a stereotaxic instrument. Highly significant genetic variation was found in the positions of lambda, bregma and several major fibre tracts with respect to interaural zero; in the locations of fibre tracts with respect to bregma; and in the location of fibre tracts with respect to each other. It was demonstrated that stereotaxic coordinates of a structure for one strain could not be used for other strains. Errors resulting from improper alignment of the head in the instrument and histological artifact were also determined. These errors showed no significant group differences, but they revealed that within‐group variation was substantilly affected by such imperfections.
Neuroplasticity of primary afferents in the neo‐natal cat and some results of early deafferentation of the trigeminal spinal nucleus
Authors: Kerr Frederick W. L. 
Published: January 2005

AbstractThe plasticity of cervical primary afferents has been investigated in young adult cats in which the trigeminal root, together with most of the ganglion, had been excised via a new approach to these structures during the first week after birth.Once degeneration debris had disappeared, bilateral ganglionectomies of the upper three cervical dorsal roots were done in five animals and the IXth and Xth roots transected on the side of the chronic trigeminal denervation in one instance; the degeneration pattern on the chronically denervated side was compared to that on the normal side.There was mild evidence of increased degeneration of the cervical afferents in the C1 segment and in the medulla (subnucleus interpolaris of V) on the chronically denervated side. The proliferation was more apparent in the kitten operated at three days of age and was only vestigial in animals operated at six or seven days; it had no appreciable tendency to extend into the large contiguous pool of denervated trigeminal neurons. There was no evidence of sprouting of the IXth and Xth nerve afferents.These observations indicate that primary afferents of the upper cervical roots and of the glossopharyngeal and vagus nerves have little neuroplastic potential even at early stages.The literature on neuroplasticity is controversial and a brief review of this together with suggestions regarding the reasons for some of these conflicts is presented. Some structural and functional effects of chronic trigeminal denervation are briefly described.
Organization of retinocollicular pathways in the cat
Authors: Harting J. K. , Guillery R. W. 
Published: January 2005

AbstractA direct pathway from the temporal retina to the contralateral superior colliculus has been demonstrated using anterograde degeneration methods. This observation of a crossed pathway to the most rostral pole of the colliculus confirms electrophysiological evidence that within each colliculus the whole eye, rather than just its hemiretina is represented.Autoradiographic tracing methods have been used to study the total tectal projection of each retina. Following intraocular injections of 3H proline, there is dense label in most of the superficial gray of the contralateral colliculus, but in this region there are several small areas of only relatively sparse label. In contrast, the superficial gray of the ipsilateral colliculus contains islands or patches of transported label. These patches are present throughout an extensive region of the colliculus and suggest that the ipsilateral retinocollicular pathway in the cat may be more substantial than earlier reports have indicated. There is no ipsilateral label within the most caudal parts of the colliculus which receives afferents from the monocular crescent of the visual field. In addition, a very small region of the rostral pole is free of ipsilateral input, and we suggest that this corresponds to the region receiving the crossed input from the temporal retina.
Changes in the magnocellular portion of the red nucleus following thoracic hemisection in the neonatal and adult rat
Authors: Prendergast Jocelyn , Stelzner Dennis J. 
Published: January 2005

AbstractThe spinal cords of newborn (0–3 day old) and adult rats were mid‐thoracically hemisected. Ninety days later a glial and connective tissue scar had formed at the lesion site in the adult hemisected rats while in neonatally lesioned animals only normal appearing regions of the contralateral spinal cord were found in the area of hemisection. Comparisons of the magnocellular portions of the red nucleus (MPRN) revealed a decrease in cell number in the MPRN contralateral (C‐MPRN) to the spinal lesion. However, only in the newborn operates was there massive cell loss accompanied by reduction in area and change in shape of the nucleus. These changes were most obvious in the caudal and ventrolateral portions of the C‐MPRN. Pooled data from each group of operates indicated that significantly more cells were lost in the C‐MPRN in the newborn than in the adult operates (p < 0.01).Neurons of the C‐MPRN which are known to project to the lower cervical and upper thoracic segments of the spinal cord (Brown, '74; Gwyn, '71) remained undamaged after the mid‐thoracic hemisection in both groups. However, neurons of this region were enlarged in both groups when compared to a similar region of the ipsilateral MPRN. These neurons were found to be more enlarged in the newborn than in the adult operates (p < 0.01).This result indicates that massive retrograde cell death takes place after a mid‐thoracic hemisection in the neonatal rat. The retrograde degeneration of axotomized neurons partially may explain why CNS regeneration is not found in the immature mammal even though many of the factors thought to limit regeneration in the adult mammal may not be apparent. The increase in cell size of C‐MPRN neurons which remain in the neonatal animals after mid‐thoracic hemisection may be related to the increase in axonal size found in the region of the rubrospinal tract rostral to the thoracic lesion reported earlier (Prendergast and Stelzner, '76a). Both the increase in axonal and perikaryal size are hypothesized to be related to the increased distribution of supraspinal axons found in the gray matter rostral to a hemisection of the neonatal rat spinal cord.
Neurogenesis in the visual system of the rat. An autoradiographic investigation
Authors: Brückner Gert , Mareš Vladislav , Biesold Dietmar 
Published: January 2005

AbstractRats of the BD III strain were injected with a single dose of 3 H‐thymidine on either the twelfth, fourteenth, sixteenth, eighteenth or twentieth day of gestation (ED 12…‥ED 20) or on the postnatal day one, three, or seven. Animals were killed at age 22 to 24 days. DNA synthesis, as an indicator of cell division, was studied in matrix precursors of nerve and glial cells in the visual centers, including the lateral geniculate body (LGB), the superior colliculus (SC) and the visual cortex (VC).It was found that proliferation of matrix precursors of nerve cells destined for all the regions studied was in progress on ED 12. In the subcortical regions (LGB, SC) this process was substantially more advanced than in the VC. The first neuroblasts appeared in the SC (ED 12) and only later (ED 14) in the LGB and VC. In comparison with the LGB, VC neuroblasts were quite rare on ED 14 and were present only in layer VI. They appeared more frequently in this region only after injection of isotope on ED 16. Matrix cell proliferation and nerve cell formation ceased in the LGB between ED 16 and ED 18. The number of labeled cells arising after injection of the isotope on ED 16 indicates that neurogenesis ceased somewhat earlier in the dorsal nucleus of the LGB than in the ventral. In the SC the last neurons arose between ED 18 and ED 20, and in the VC, with the possible exception of a few granular neurons (which may continue division into the first few days postnatally), proliferation continued until the end of gestation.The origin of neuroblasts initially followed a caudo‐rostral gradient. Later, the times of neurogenesis in the regions studied overlapped significantly. This is clear, for example, on ED 16, when neurogenesis in the mesencephalic SC continued for about two days longer than in the more rostral LGB, and coincided with that in the VC, especially in the deep layers. The end of neurogenesis in the LGB, especially in the ventral nucleus, coincided with the time of neurogenesis in the deep cortical layers.In the VC, and partly also in the SC, an inside‐out pattern of proliferation and neuron formation was confirmed. The times of proliferation of precursor cells, with the exception of the very end of neurogenesis, substantially overlapped within both these regions. The degree of this overlapping, described in terms of Labeling Index values, decreased towards the end of the neurogenetic period.Division of neuroglial cell precursors, started as early as on ED 14 in/for subcortical centers (LGB, SC), but not until ED 18 in/for the VC. A few labeled endothelial‐like cells were observed in all regions studied after isotope injection on ED 12.
Organization and development of brain stem auditory nuclei of the chicken: Ontogeny of N. magnocellularis and N. laminaris
Authors: Rubel Edwin W. , Smith Daniel J. , Miller Laurie C. 
Published: January 2005

AbstractNucleus magnocellularis (NM) and nucleus laminaris (NL) are, respectively, second‐ and third‐order auditory nuclei in the chicken brain stem. In this report the morphogenesis of these nuclei is examined. The times of origin of the cells of these nuclei were studied with 3H‐thymidine autoradiography. The number of cells in each nucleus and their rostro‐caudal distribution within each nucleus was determined in Nissl‐stained sections at 9, 11, 13, 15, 17, 19, and 21 days of incubation. For the above ages the volumes of NM and NL were also calculated planimetrically and the rostro‐caudal distribution of volume within each nucleus was studied.The results indicate that the times of origin of NM and NL neurons do not overlap — the cells of NM are formed at around 60 hours of incubation, while those of NL are formed at around 84 hours. At nine days, both nuclei have a roughly equal complement of cells; however by 21 days (hatching) the number of NM neurons has decreased by 18%, while the number of NL neurons has decreased by 84%. In both nuclei most of the cell death occurs in the period between 11 and 13 days, during which time NL assumes a laminar appearance. A rostro‐caudal gradient of cell death was found for both nuclei. The times of volume increases in NM and NL commence at the end of the period of cell death, beginning at 13 days for NM and at 17 days for NL, whose cell death is more protracted. For both nuclei a rostro‐caudal gradient of volumetric expansion was also found.