bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ontogeny of monoamine neurons in the locus coeruleus, raphe nuclei and substantia nigra of the rat
Authors: Lauder Jean M. , Bloom Floyd E. 
Published: January 2005

AbstractSynaptogenesis was studied in the monoamine (MA) cell groups locus coeruleus (LC), dorsal and medial raphe nuclei (RN) and substantia nigra, zona compacta (SN) between day 18 of gestation and postnatal day 60 using ethanolic phosphotungstic acid (E‐PTA) to visualize synaptic profiles. Nuclear area, and cellular packing density (inversely proportional to area of neuropil) were also determined.As determined using the E‐PTA method, synaptogenesis begins in the neuropil of the SN first, on or before 18 days of gestation, and in the LC and RN at 19 days. Synaptogenesis on MA cell perikarya is first observed in the SN, on or before 18 days, and in the LC and RN at 20 days. The onset of somatic synaptogenesis coincides with the beginning of nuclear growth and development of the neuropil (decrease in cellular packing density) in all MA cell areas, raising the possibility of common factors in the initiation of these processes.Nonsynaptic contacts precede the appearance of synaptic profiles both in the neuropil and on the somata of the MA cells of the LC, RN and SN, and may represent precursors of mature synapses or desmosome‐like contacts. Somatosomatic nonsynaptic contacts occur only prenatally between adjacent MA neurons in the LC, RN and SN.Although some synaptogenesis occurs prenatally in these MA cell groups (indicating that these parts of the MA circuitry may be functional before birth), most of this synaptogenesis occurs postnatally and continues into adulthood. Since such synaptogenesis does not begin until 2–4 days prior to birth, whereas these neurons and their processes exhibit MA fluorescence as early as 12–14 days of gestation, they apparently are capable of synthesizing transmitter and proliferating terminals before they themselves are innervated.
Functional role of efferents to the avian retina. I. Analysis of retinal ganglion cell receptive fields
Authors: Pearlman Alan L. , Hughes Charles P. 
Published: January 2005

AbstractReceptive fields of retinal ganglion cells were analyzed during extracellular microelectrode recordings in the optic tract of the lightly anesthetized pigeon. Four major types of receptive field can be distinguished among the 359 fibers studied. Twenty‐five percent of the receptive fields are relatively simple, responding at on and at off to stationary spots of light in the central region. All of the receptive fields have inhibitory surrounds of varying strength that do not produce a response when illuminated alone, but antagonize responses from the central region. Motion sensitive units comprise 15% of the recorded population; they are similar to the on‐off center type except that responses to stationary stimuli are absent or very weak while responses to moving stimuli are vigorous. Directionally selective units also have the basic features of on‐off, inhibitory surround cells, but respond to moving stimuli well from the preferred direction and not at all from the null direction. Directional cells have a broad range of null directions; in about one‐third of the units the range becomes broader when the stimulus involves both center and surround of the receptive field, thus enhancing directional selectivity. Directionally selective units are common, comprising 38% of the units studied. Cells unresponsive to stimuli moving from anterior in the visual field are much more common than other types, while cells unresponsive to stimuli from posterior in the field are rare. A few units (11 %) respond only at on or at off to stationary stimuli in their receptive field centers; they also have antagonistic but unresponsive receptive field surrounds. The area of the visual field sampled is uniform in regard to the relative numbers of the four major receptive field types.
Afferents to the cerebellar lateral nucleus. Evidence from retrograde transport of horseradish peroxidase after pressure injections through micropipettes
Authors: Eller Theodore , Chan‐Palay Victoria 
Published: January 2005

AbstractHRP was injected by pressure from glass capillary micropipettes unilaterally into the lateral nucleus of rat so as to encompass the entire nucleus, but without spread into the interpositus nuclei. The cells of origin of the afferents to the lateral nucleus were studied after retrograde transport of the HRP. The reticulotegmental nucleus of the pons was labelled bilaterally and is the major source of crossed and uncrossed reticular inputs. The pontine nuclei also provide extensive crossed and uncrossed afferents. The inferior olive gives a large crossed olivo‐lateral nucleus projection and a minor uncrossed input. The trigeminal nuclear complex — the nucleus of the spinal tract and the mesencephalic, principal sensory, and motor nuclei — all provide uncrossed afferents. The rostral portion of the lateral reticular nucleus gives a small crossed and uncrossed projection while the perihypoglossal nuclei and the dorsal parabrachial body give crossed afferents to the lateral nucleus. The norepinephrine afferent system from the locus coeruleus is represented by one or two heavily labelled cells and the serotonin raphe systems come from at least five raphe subgroups, the dorsal, superior centralis, pontis, obscurus and magnus nuclei. No evidence was found for commissural fibers between ipsilateral or contralateral cerebellar nuclei, or afferent axons, from the spinocerebellar nuclei and the paramedian reticular nucleus. The significance of these sources of afferent inputs to the lateral cerebellar nucleus is discussed. The question is raised of the direct relationship between size of terminal axonal arborization and the quantity of HRP granules present in a cell after retrograde transport. The limitations of the HRP method for detecting subtle local differences in the distribution of afferents within the heterogeneous groups of neurons in the lateral nucleus are discussed.
Convergent thalamic and mesencephalic projections to the anterior medial cortex in the rat
Authors: Beckstead Robert M. 
Published: January 2005

AbstractSmall microelectrophoretic deposits of horseradish‐peroxidase (HRP) were placed at various loci within the gray matter of the rat's anterior medial cortex. A comparison of the patterns of retrograde cell‐labeling charted in 26 such cases confirmed earlier findings in fiber‐degeneration studies according to which the respective thalamocortical projections of the mediodorsal (MD) and anteromedial nucleus (AM) overlap each other over a wide region of the anterior medial cortex. This region of thalamocortical convergence, extending from pregenual levels caudalward as far as the anterior border of the retrosplenial cortex, corresponds almost exactly to the cortical region from which locally deposited HRP was found to be transported so as to label cells in one or both of two mesencephalic cell groups: the ventral tegmental area (AVT) dorsal and lateral to the interpeduncular nucleus, and the medial one‐quarter of the pars compacta of the substantia nigra (SNC). The reported findings suggest that the corticipetal projections of AVT and SNC are organized so that AVT projects largely to the area infraradiata of the pregenual cortex which receives its major thalamocortical projection from MD, whereas SNC‐efferents are distributed to the area infraradiata of the supracallosal cortex which receives most of its thalamocortical afferents from AM; the two mesencephalocortical projections do, however, appear to overlap each other in a region of the medial cortex immediately posterior to the level of the genu corporis callosi. HRP injected into the medial cortex of five rats pre‐treated with 6‐hydroxydopamine, a drug that produces chemical lesions of catecholamine neurons, failed to label any cells in AVT and SNC but did label numerous cells in MD and AM. This finding suggests that the ventral tegmental cells projecting to the anterior medial cortex are exclusively dopamine neurons.
Differentiation of Purkinje cells and their relationship to other components of developing cerebellar cortex in man
Authors: Zecevic Nada , Rakic Pasko 
Published: January 2005

AbstractThe differentiation of Purkinje cells and their relationship to other components of the developing cerebellar cortex were analyzed by the Golgimpregnation method and by electron microscopy in human specimens of various pre‐ and postnatal ages. The three stages of Purkinje cell maturation that have been previously recognized in other species are also evident in man: the first stage occupies primarily the fourth fetal month (12–16 weeks); the second stage lasts through the fifth, sixth and seventh fetal months (16–28 weeks); the third stage extends throughout the remaining period of intrauterine life and the first postnatal year and continues at a slow rate thereafter. During the first stage, Purkinje cells are distributed in a layer, several rows deep. Their bipolar somas are relatively smooth and have only a few processes at the apical and basal cell poles. In the 3‐month period of the second stage, Purkinje cells become gradully organized into a single row. Their somas become invested with additional randomly oriented dendritic processes and numerous somatic spines (pseudopodia). The first morphologically well‐defined synapses appear on the Purkinje cell somatic spines and on their immature dendritic shafts at the beginning of the second stage and become more prominent during the period from 18 to 24 weeks. In the third stage, the dendritic arbor becomes flattened in the plane transverse to the folium and somatic spines disappear. Spines appear on the secondary and tertiary dendrites between the twenty‐fourth and twenty‐eighth fetal weeks and continue to increase in number during the entire third stage as new dendritic branches develop. These observations indicate that cellular maturation and synaptogenesis in the primate cerebellum differ from these events in non‐primate species, with respect to time of birth, in the relative duration of each phase and in the total time necessary for neuronal differentiation. The protracted time of differentiation and the slow growth of Purkinje cell dendrites in man may be due to the numerically complex relationships existing between granule and Purkinje cells. It is probably not simply a reflection of the larger size of human Purkinje cells and their dendrites.
Midbrain, diencephalic and cortical relationships of the basal nucleus of meynert and associated structures in primates
Authors: Jones E. G. , Burton H. , Saper C. B. , Swanson L. W. 
Published: January 2005

AbstractThe structure and connectivity of the basal nucleus of Meynert, the substantia innominata in which it lies, and certain related areas have been examined in New World and Old World Monkeys, using retrograde and anterograde axonal transport methods.Experiments using the retrograde, horseradish peroxidase method confirm the observations of Kievet and Kuypers ('75) that the basal nucleus and substantia innominata project directly, heavily and with a somewhat crude topography upon the neocortex.Experiments involving the anterograde, autoradiographic method show that the basal nucleus and substantia innominata form part of a complex pathway that links them together with the lateral hypothalamus, certain parts of the amygdala and the peripeduncular nucleus of the midbrain. The peripeduncular nucleus is often regarded as a part of the central auditory pathway; it gives rise to a fiber bundle of considerable size that ascends on the dorsal surface of the ipsilateral optic tract and terminates ultimately in the lateral hypothalamic area of both sides. As well as distributing fibers to the basal nucleus, substantia innominata and lateral hypothalamus, this pathway provides a heavy projection to a cytoarchitectonically distinct posterior part of the lateral nucleus of the amygdala, the medial and intercalated nuclei of the amygdala and a less dense projection to the bed nucleus of the stria terminalis.Certain parts of the hypothalamus and possibly the preoptic areas give rise to a complementary descending pathway that distributes fibers to the ipsilateral basal nucleus, substantia innominata and amygdala, and ends in the peripeduncular nuclei of both sides. Decussating fibers in both the ascending and descending pathways cross in the ventral supraoptic commissure.It is concluded that the basal nucleus should include most of the aggregated and unaggregated large cells that lie in the substantia innominata and which in places intrude upon the preoptic regions and the nucleus of the diagonal band of Broca. Together, these may form a complex that receives inputs from a variety of brainstem sources, and projects widely and diffusely upon all cortical structures of the telencephalon.
Regional specialization in the golden hamster's retina
Authors: Y‐C Tiao , Blakemore Colin 
Published: January 2005

AbstractGanglion cells were counted and measured in whole mounts of the hamster's retina, stained with methylene blue. Their density varies between about 1,000/mm2 at the edge of the retina to about 5–6,000/mm2 in a broad area centralis centred about 1.9 mm (39 deg) directly temporal to the optic disk. Maps of cell density show a long horizontal extension of the dense area in the nasal direction. The sizes of ganglion cell somata fall into two main groups—small cells (5–11 μm diameter) and large cells (>11 μm), the latter including a small proportion of giant cells (>17 μm). All three classes of cells are maximal in density in the area centralis, although the small cells are relatively more numerous there. The total number of cells is about 114,000 with about 63,000 small cells and about 51,000 large. The optic nerve contains about 69,000 unmyelinated axons and about 50,000 myelinated axons, suggesting that the latter are the fibres of the larger ganglion cells. It is likely that the projections of the centres of the areae centrales of the two eyes are normally divergent in space; they are therefore not on “corresponding retinal points.”
Synapse formation in the mouse olfactory bulb Quantitative studies
Authors: Hinds James W. , Hinds Patricia L. 
Published: January 2005

AbstractA quantitative study of synapse formation in the mouse olfactory bulb has been carried out using serial sections. Volumetric synaptic density as well as absolute number of synapses per olfactory bulb for eight distinct synaptic types have been determined at 15 different ages, from the beginning of synapse formation at embryonic day 14 (E14) to postnatal day 44 (P44). Synapses are first found in appreciable numbers at E15 when both axo‐dendritic and a few dendrodendritic synapses occur in the presumptive glomerular layer. Initial synapse formation correlates closely with the reorientation of mitral cells from a primitive tangential to a defintive radial direction. Synapse formation by mitral cell dendrites occurs after mitral cell axons have grown into the future olfactory cortical areas, either simultaneous with or before synapse formation by these axons.Virtually all synaptic types detected in adults have been found on the day of birth, consistent with the idea that olfaction is an important sensory modality for newborn mice. Volumetric density of a given synaptic type generally increases 50–100 times during development while the absolute number increases about 1,000 times. Synapses in glomeruli develop more precociously than those in the external plexiform and internal granular layers, which correlates well with the time of origin and differentiation of the principal postsynaptic elements of these two divisions (mitral cells and internal granule cells) Correlation of the time of synapse formation of various synaptic types with their putative excitatory or inhibitory role determined in adult studies suggests that excitatory synapses generally form somewhat earlier, although throughout nearly all of synaptic development, both excitatory and inhibitory synapses are present.Reciprocal dendro‐dendritic synapses in the external plexiform layer appear to have a special mode of formation. It is suggested that a granule‐to‐mitral dendro‐dendritic synapse only forms next to an already existing mitral‐to‐granule synapse on the same gemmule.
Efferents from medial basal forebrain and hypothalamus in the rat. I. An autoradiographic study of the medial preoptic area
Authors: Conrad Lily C. A. , Pfaff Donald W. 
Published: January 2005

AbstractEfferent projections from the medial and periventricular preoptic area, bed nucleus of the stria terminalis and nuclei of the diagonal band were traced using tritiated amino acid autoradiography in albino rats.Medial and periventricular preoptic area efferents were not restricted to shortaxon projections. Ascending projections from the medial preoptic area (mPOA) were traced through the diagonal band into the septum. Descending mPOA axons coursed in the medial parts of the medial forebrain bundle. Projections to most hypothalamic nuclei, including the arcuate nucleus and median eminence, were observed. In the midbrain, mPOA efferents were distributed in the central grey, raphe nuclei, ventral tegmental area and reticular formation. Projections from the mPOA were also observed to the amygdala through the stria terminalis, to the lateral habenula through the stria medullaris, and to the periventricular thalamus.Axons of the most medial and periventricular preoptic area (pvPOA) neurons had a distribution similar to more lateral mPOA neurons but their longest‐axoned projections were weaker. The pvPOA did not send axons through the stria medullaris but did project more heavily than the more lateral mPOA to the arcuate nucleus and median eminence.Projections from the bed nucleus of the stria terminalis (nST) were in most respects similar to those from the medial preoptic area, with the major addition of a projection to the accessory olfactory bulb.The nuclei of the diagonal band of Broca (nDBB) gave a different pattern of projections than mPOA or nST, projecting, for instance, to the medial septum and hippocampus. Descending nDBB efferents ran in the ventral portion of the medial forebrain bundle. Among hypothalamic cell groups, only the medial mammillary nuclei received nDBB projections. nDBB efferents also distributed in the medial and lateral habenular nuclei and the mediodorsal thalamic nucleus.
Development of neurons in the visual cortex (area 17) of the monkey (Macaca nemestrina): A Golgi study from fetal day 127 to postnatal maturity
Authors: Lund J. S. , Boothe R. G. , Lund R. D. 
Published: January 2005

AbstractThe morphological maturation of several varieties of neurons of cortical area 17 have been followed in Golgi Rapid preparations from Macaque monkeys ranging in age from fetal day 127 to maturity. A developmental sequence common to all varieties of neuron is described. Maturation occurs at the same rate at all cortical depths and appears to relate to the size of the neuron rather than to factors such as generation time, arrival at a final laminar position or cell type. The characteristic laminar patterns of cell type distribution and the specific axonal and dendritic arborisations seen in the adult are generated in the earliest stages of growth and do not occur as the result of elimination from a wider, less precise, distribution. During the period from birth to postnatal week 8 a marked increase in the numbers of dendritic spines is seen in all varieties of neuron including those which will be spine‐free in the adult. Following this period an equally marked reduction in spine numbers occurs, initially rapid but continuing at a slower rate even nine months postnatally. Possible relationships between these postnatal dendritic spine changes and the extreme sensitivity of the system to visual input during the early postnatal weeks are discussed.
Preparation of antisera to neurofilament protein from chicken brain and human sciatic nerve
Authors: Dahl Doris , Bignami Amico 
Published: January 2005

AbstractAntigens isolated by hydroxyapatite chromatography from human sciatic nerve (SN1 protein) and from 8 M urea extracts of chicken brain were selectively localized by immunofluorescence to neurofibrils in rat and chicken CNS. Absorption of the antisera with SN1 protein, chicken antigen or GFA protein abolished the staining. Antisera raised against antigen isolated with the same procedure from buffer extracts of chicken brain stained both neurofibrils and glial fibrils by immunofluroescence. Neurofibrillary staining was selectively abolished by absorption of the antisera with SN1 protein. Antisera prepared against axonal preparations isolated from bovine white matter only stained astroglia and were thus undistinguishable from anti‐GFA sera in this respect. The data suggested that the protein subunits of neurofilament and glial filaments, although difficult to separate in brain extracts by standard biochemical procedures and by subcellular fractionation in bovine white matter, still retain immunological specificity. In addition, the immunological cross reactivity between human and chicken antigens suggested that neurofilaments, as other constituents of the cytoskeleton such as microtubules and actin microfilaments, show a high degree of evolutionary stability.
The thalamic afferents to the inferior parietal lobule of the rhesus monkey
Authors: Kasdon David L. , Jacobson Stanley 
Published: January 2005

AbstractThe inferior parietal lobule (IPL) of the monkey is the homologous region to the supramarginal and angular gyri in man, subserving language and related cortical functions. We have examined specific zones of the IPL by injecting eight monkeys with retrogradely transported HRP, and located the positive cells in the thalamic sections with the assistance of an X‐Y plotter and reference to the atlas of Olszewski ('52). Projections to the IPL were found in the following thalamic nuclei: Anterior (Anterior Medial, Anterior Ventral); Lateral (Ventral Anterior, Ventral Anterior magnocellularis, Ventral Lateral caudalis, Pulvinar oralis, medialis, lateralis and inferior, Lateral Posterior and Lateral Dorsal); Medial (Medialis Dorsalis densocellularis, parvocellularis, and multiformis); Midline and Intralaminar (Centralis densocellularis, Centralis lateralis, Centralis inferior, Centralis superior lateralis, Subfascicularis parvocellularis, Paracentralis and Parafascicularis); and Posterior (Limitans, Suprageniculatus and Geniculatus Medialis magnocellularis).A major projection to the superior portion of the IPL was from the anterior nuclei and Paracentralis of the intralaminar group. Ventralis Lateralis and oral Pulvinar projected primarily to the anterior‐inferior portion of the IPL, whereas Lateral Posterior projected most strongly to the anterior and superior portion. The major projection of the lateral Pulvinar was to the mid‐superior portion of the IPL and to area 19. The projections of the inferior Fulvinar were heaviest to area 19, but there was some overlap in the mid‐superior portion of the IPL with the medial and lateral Pulvinar. The major projection from the posterior thalamic nuclear complex was to the mid‐IPL.The heterogeneous input from the thalamus to the IPL was not anticipated on the basis of prior anterograde or retrograde degeneration studies, and suggests that classical subdivisions of specific and associational thalamic nuclei should be revised with the axonal transport methods of study.