bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single‐unit study of lateral line cells in the optic tectum of Xenopus laevis: Evidence for bimodal lateral line/optic units
Authors: Lowe D. A. 
Published: January 2005

AbstractResponses of single units in the Xenopus tectum to stimulation of the contralateral anterior lateral line nerve (cALLN) and optic nerve were studied. Cells responded to cALLN stimulation with a phasic burst of spikes that was repeatable between trials; latencies ranged from 4 to 23 msec. The most excitable cells were located in layer 6 of the ventrolateral tectum. Cells responding to stimulation of the ipsilateral ALLN were far less numerous and robust, and showed latencies 3–10 msec greater than those of contralateral responses. Tectal cell responses to cALLN nerve stimulation grew progressively to saturation with stimulus voltage and paralleled the growth of the ALLN compound action potential; cells responded to stimulation of either supra‐ or infraorbital branches of cALLN. These observations indicate convergence of primary lateral line afferents in the medulla and/or tectum. Lateral line tectal cells showed strong habituation at interstimulus times less than 8–20 seconds. Experiments on bimodal cells revealed facilitatory and inhibitory interactions between optic and lateral line inputs. Some cells responded to stimulation of either lateral line or optic nerves, with combined stimulation producing responses exceeding the sum of responses to separate nerve stimulation. In other cells the response to optic nerve stimulation was markedly increased by lateral line nerve stimulation, despite the absence of response to lateral line nerve stimulation alone. Facilitation was also evident in cells that responded only to combined stimulation of lateral line and optic nerves. Some cells exhibited an early (5–10 msec) and late (20–40 msec) response to optic nerve stimulation; lateral line nerve stimulation, despite eliciting no response itself, produced strong facilitation of the early but almost complete suppression of the late optic nerve response.
Functional organization of primary visual cortex in the mink (Mustela vison) and a comparison with the cat
Authors: LeVay Simon , McConnell Susan K. , Luskin Marla B. 
Published: January 2005

AbstractThe functional organization of geniculocortical afferents and the visual responses of neurons in primary visual cortex (area 17) were studied in barbiturate‐anesthetized, paralyzed minks and cats.Responses of the afferents were studied after silencing intrinsic cortical activity with injections of kainic acid. In both species, afferents were segregated into patches on the basis of eye of origin. In the mink, but not in the cat, there was a further segregation on the basis of center type, with on‐ and off‐center afferents terminating in alternating, partially overlapping patches.The visual responses of cortical neurons in the mink showed many similarities to those in the cat. Nearly all units were orientation‐selective, and there was a columnar organization for preferred orientation. Many units were selective for one direction of movement. Within the binocular segment of cortex, although many units could be driven from either eye, there was a marked bias toward the contralateral eye compared to the cat. There was a columnar system for ocular dominance, but contralateral eye columns were wider than ipsilateral.In both species, a quantitative study was made of the responses of cortical neurons to stationary, flashing slits as a function of position in the receptive field. In the mink, and less clearly in the cat, units could be identified as simple or complex on the basis of the spatial separation or overlap of “on” and “off” discharge zones. In both species, simple cells were found most commonly in layers IV and VI, while layer V contained the greatest proportion of complex cells.The relative strengths of the on and off discharges of single cells were also measured. In the mink, many units gave better overall responses to the on or off phase of the stimulus, and 15% showed a strong (>9:1) preference for one or the other, compared to 4% in the cat.In the mink, units with a common preference for the on or off phase of stationary stimuli were arranged in columnar aggregates, a feature of cortical organization that was not found in the cat. These columns probably result from the partial segregation of on‐center and off‐center geniculate afferents within layers IV and VI of the mink's cortex. On‐dominated columns were, however, wider or more numerous than off‐dominated columns.
Development of the precerebellar nuclei in the rat: II. The intramural olivary migratory stream and the neurogenetic organization of the inferior olive
Authors: Altman Joseph , Bayer Shirley A. 
Published: January 2005

AbstractSequential thymidine radiograms from rats labeled on days E13 and E14, and killed at daily intervals thereafter, were analyzed to trace the migratory route and settling pattern of neurons of the inferior olive. Long‐survival thymidine radiograms from perinatal rats injected on day E14 were used to subdivide the inferior olivary complex on the basis of neurogentic criteria.The inferior olivary neurons originate on days E13 and E14 in the primary precerebellar neuroepithelium. The olivary neurons labeled on day E14 (the late generated components) translocate into the inferior olivary premigratory zone on day E15. On day E16 these cells join the olivary migratory stream, which follows an intramural circumferential path between the gray and white matters of the medulla. By day E17 the olivary migratory stream is reduced to a small band near the corpus of the inferior olive, which has been settled by this time by neurons generated on day E13. As a result, the unlabeled cells are situated on day E17 dorsomedially and the labeled cells ventrolaterally. The regional segregation of neurons forming subdivisions of the inferior olive begins on day E18, and by day E19 the major subdivisions are all recognizable.In thymidine radiograms from perinatal rats injected on day E14, four neurogenetic components can be distinguished in the inferior olive, those composed: (1) of unlabeled cells (generated on day E13), (2) of predominantly unlabeled cells, (3) of predominantly labeled cells (generated on day E14), and (4) of labeled cells. By combining these neurogenetic differences with the morphological features of the inferior olivary complex, we propose a modification of the currently accepted classification. The four major divisions of the inferior olive are the successively produced posterodorsal olive, anterolateral (principal) olive, posteroventral olive, and anteroventral olive. The location and configuration of these divisions are illustrated in relation to the traditional classification both in the coronal and the sagittal plane.
An extensive intrinsic association fiber system within cat area 7 revealed by anterograde and retrograde axon tracing methods
Authors: Callahan Eileen C. , Haberly Lewis B. 
Published: January 2005

AbstractThe associational connections within area 7 on the crown of the middle suprasylvian gyrus in adult cats were investigated with extracellular axon tracing techniques. Injections of wheat germ agglutinin conjugated to horseradish peroxidase or of 3H‐proline into area 7 revealed the presence of widespread intrinsic connections that extend over the rostral to caudal extent of the middle suprasylvian gyrus (up to 10 mm in one direction from injection sites). The connections have a complex organization with cell bodies and particulate label concentrated in patches. The patches are irregular in shape and do not form any obvious pattern. Although the transported label is concentrated in patches, large numbers of retrogradely labeled cells and significant quantities of anterogradely transported label are found in the spaces between patches. The long associational connections originate from cells in layers 2–6 and project to all cortical layers. Pyramidal cells are the primary source of the projections.
Localization of hydroxyindole‐O‐methyltransferase‐like immunoreactivity in photoreceptors and cone bipolar cells in the human retina: A light and electron microscope study
Authors: Wiechmann Allan F. , Hollyfield Joe G. 
Published: January 2005

AbstractThe localization of the melatonin‐synthesizing enzyme hydroxyindole‐O‐methyltransferase (HIOMT) was examined by light and electron microscopic immunocytochemistry in the human retina. HIOMT‐like immunoreactivity was observed in the photoreceptor layers and the inner nuclear layer (INL). The immunoreactive cells in the INL were more numerous in the central retina than in the peripheral retina and sent processes to both the outer plexiform and inner plexiform layers. The HIOMT immunoreactivity in the inner plexiform layer (IPL) appeared as punctate terminals in the proximal and distal one‐thirds of that layer.At the ultrastructural level, HIOMT‐like immunoreactivity was localized to the cytoplasm of rod and cone photoreceptors and to a population of cone bipolar cells. HIOMT‐immunoreactive bipolar cell dendrites were observed to make both invaginating and flat synaptic contacts with cone pedicles. No immunoreactive invaginating contacts in rod spherules were observed. HIOMT immunoreactivity was observed in the bipolar cell cytoplasm in the INL, and in the bipolar synaptic terminals in the IPL. These terminals contained synaptic ribbons, which formed synaptic contacts with unlabeled cells in the IPL. HIOMT radioenzymatic assays confirmed the presence of HIOMT in the human retina. Average HIOMT activity of eight donors was determined to be 15.0 pmol/mg protein/hour ± 7.2 S.D. The ultrastructural localization of HIOMT observed in this study, combined with reports from other laboratories, suggests that the cytoplasm of the photoreceptors and a population of cone bipolar cells may be the sites of melatonin synthesis in the human retina.
Sources of presumptive glutamergic/aspartergic afferents to the rat ventral striatopallidal region
Authors: Fuller T. A. , Russchen F. T. , Price J. L. 
Published: January 2005

AbstractThe distribution of presumptive glutamergic and/or aspartergic neurons retrogradely labeled following injections of 3H‐D‐aspartate (3H‐D‐Asp) into the ventral Striatopallidal region was compared with the distribution of neurons labeled by comparable injections of wheat germ agglutunin‐horseradish peroxidase (WGA‐HRP). The afferents labeled by 3H‐D‐Asp were a subset of those labeled by WGA‐HRP. The major sources of afferents to the nucleus accumbens and olfactory tubercle that could be labeled by 3H‐D‐Asp were in the medial frontal and insular cortices; the olfactory cortex; the lateral, basolateral, and basomedial amygdaloid nuclei; and the midline nuclear complex of the thalamus. The corresponding afferents to the ventral pallidum arose in the central, medial, and basomedial amygdaloid nuclei and the midline thalamic nuclei. In addition, the nucleus of the lateral olfactory tract was moderately or heavily labeled by 3H‐D‐Asp injections into all three areas, and cells were labeled in the subiculum following injection in the anteromedial part of the nucleus accumbens. Conversely the ventral Striatopallidal structures themselves were, at best, sparsely labeled by any of the 3H‐D‐Asp injections. Neurons in the substantia nigra, ventral tegmental area, dorsal raphe, and locus coeruleus were labeled by WGA‐HRP but not by 3H‐D‐Asp, except for an occasional cell in the raphe. The results indicate that 3H‐D‐Asp is a specific retrograde tracer and suggest that there are widespread, presumably excitatory, glutamergic and/or aspartergic inputs to the ventral striatum and pallidum.
Axon collaterals in the thalamic reticular nucleus from thalamocortical neurons of the rat ventrobasal thalamus
Authors: Harris Roger M. 
Published: January 2005

AbstractThalamocortical relay neurons from the rat ventrobasal nucleus were identified physiologically and injected intracellularly with horseradish peroxidase. The axons of those cells were followed through serial sections in order to determine if collaterals were given off within the ventrobasal nucleus or the thalamic reticular nucleus. No local collaterals were seen in the ventrobasal nucleus, thus indicating that interactions between relay cells in this nucleus are minimal. Of axons that could be followed into the internal capsule, 76% gave off visible collaterals in the thalamic reticular nucleus. Half of these axons had collaterals showing extensive branching with the potential of innervating a large number of thalamic reticular neurons. The other half had short, simple branches of restricted extent. No correlations were found between the physiological properties of a cell and the existence or extent of axon collaterals. These results describe the anatomical basis for the initial part of a feedback loop through the thalamic reticular nucleus that provides the major inhibitory influence on rat ventrobasal neurons.
Evidence for parallel processing in the frog's auditory thalamus
Authors: Hall Jim C. , Feng Albert S. 
Published: January 2005

AbstractWe have conducted anatomical and physiological experiments to investigate the functional organization of the dorsal thalamus in the northern leopard frog (Rana pipiens pipiens). Our studies provide evidence for parallel auditory processing at this level of the frog's brain. Acoustically evoked potentials were recorded from the posterior and central thalamic nuclei and several differences in sound‐evoked activity were noted between them: (1) the amplitude of acoustically evoked potentials (AEPs), in response to a standard search stimulus, was always greater in the central, as opposed to the posterior, nucleus; (2) the posterior, but not central, nucleus exhibited the phenomenon of nonlinear summation when 350‐Hz and 1,700‐Hz tones were presented simultaneously rather than individually; and (3) the central, but not posterior, nucleus showed selectivity for the repetition rate of pulsed sound signals. The posterior and central thalamic nuclei also possessed distinct innervation patterns as revealed by the HRP transport patterns arising from these structures. The central nucleus was reciprocally connected with the major auditory relay stations along the frog's central auditory pathway including the superior dive, nucleus of the lateral lemniscus, and the torus semicircularis. Major projections to the lateral thalamic nucleus, ventral hypothalamus, and the telencephalic striatal complex were also observed. The posterior nucleus, on the other hand, established reciprocal connections primarily with the medial reticular nucleus, ventral mid‐brain tegmentum, and structures constituting of the ventral thalamic nuclei, particularly the nucleus of Bellonci. Thus, time and frequency cues contained within the species mating call, and conveying information concerning species identity, appear to be processed independently within the frog's thalamus with separate neural channels for each.
Morphology of expiratory neurons of the Bötzinger complex: An HRP study in the cat
Authors: Otake Kazuyoshi , Sasaki Hiroshi , Mannen Hajime , Ezure Kazuhisa 
Published: January 2005

AbstractIn anesthetized and artificially ventilated cats, the physiological and morphological properties of expiratory neurons or their axons of the Bötzinger complex (BOT) were studied using intracellular recording and intracellular HRP labeling techniques. Thirteen expiratory neurons (nine cell somata and four axons) were successfully stained. Four of them were motoneurons, having relatively large cell somata in the retrofacial nucleus (RFN) and axons without any collaterals inside the brainstem. All the motoneurons showed a plateau shape of depolarization potentials during the expiratory phase. Any of the other nine expiratory neurons exhibited augmenting type firing or membrane potential changes during the expiratory phase. In five out of nine augmenting neurons, cell somata were stained and located ventral to the RFN. In four, only axons were stained. The majority of the augmenting neurons had two major axonal branches: one traveling toward the contralateral side and the other descending ipsilaterally in the brainstem. The most striking feature of the axonal trajectory was that all of the stained augmenting expiratory neurons, including the axons, had collateral branches with synaptic boutons in the BOT area, thus indicating that BOT expiratory neurons interact with some respiratory neurons in the BOT area and its vicinity.
Distribution of GABA‐immunoreactive neurons in the basal ganglia of the squirrel monkey (Saimiri sciureus)
Authors: Smith Y. , Parent A. , Seguela P. , Descarries L. 
Published: January 2005

AbstractThe distribution of GABA‐immunoreactive neurons was visualized in the basal ganglia of the squirrel monkey (Saimiri sciureus), by using a highly specific antiserum raised against GABA‐glutaraldehyde‐lysyl‐protein conjugate and revealed by the indirect peroxidase‐antiperoxidase immuno‐histochemical method. In the dorsal striatum, GABA‐immunoreactive nerve cell bodies were small to medium in size (sectional area ranging from 90 to 125 μm2), but some larger ones (500‐600 μm2) were also found. These cells displayed no obvious clustering but were significantly more numerous in the caudate nucleus than in the putamen; their number was also markedly greater at caudal than at rostra1 striatal levels. A moderate number of evenly distributed positive axon terminals were visible in both the caudate nucleus and the putamen. In the ventral striatum, GABA‐immunoreactive nerve cell bodies and axon terminals were seen in fair number within the nucleus accumbens and in the deep layers of the olfactory tubercle. Many positive terminals but no somata were found in the islands of Calleja. In the globus pallidus, virtually all nerve cell bodies were GABA‐immunoreactive and the neuropil exhibited a multitude of positive terminals. In the Substantia innominata, clusters of small, globular GABA‐immunoreactive somata were scattered among aggregates of larger, nonimmunoreactive neurons belonging to the nucleus basalis, and the whole region showed a low to moderate number of evenly spread GABA‐positive terminals. In the subtha‐lamic nucleus, nerve cell bodies were generally surrounded by several GABA‐positive terminals but were not themselves immunoreactive. The substantianigra showed many GABA‐immunoreactive somata, which predominated in the pars lateralis and diminished progressively in number along the latero‐medial axis of the pars reticulata. These cells formed a rather pleomorphic group comprising round, fusiform, or polygonal elements of relatively large size (sectional area ranging from 200 to 800 μm2). In the pars compacta and ventral tegmental area, a few GABA‐immunoreactive neurons of small size were dispersed among larger, unreactive neurons. In both pars lateralis and pars reticulata of the substantia nigra, the number of GABA‐positive termi‐nals was high and their distribution was rather uniform; a smaller number were visible in the pars compacta of the substantia nigra and in the ventral tegmental area.The present results demonstrate that GABA‐containing neurons are widely and heterogeneously distributed in the various components of the squirrel monkey's basal ganglia. Such normative data should be useful as a basis for further investigations of the functional role of GABA in the brain of primates.
Evidence for the inhibitory neurotransmitter γ‐aminobutyric acid in aspiny and sparsely spiny nonpyramidal neurons of the turtle dorsal cortex
Authors: Blanton Mark G. , Shen Janet M. , Kriegstein Arnold R. 
Published: January 2005

AbstractIn order to learn more about the anatomical substrate for γ‐aminobutyric acid (GABA)‐mediated inhibition in cortical structures, the intrinsic neuronal organization of turtle dorsal cortex was studied by using Golgi impregnation, immunohistochemical localization of GABA and its synthetic enzyme glutamic acid decarboxylase (GAD), and histochemical localization of the presynaptic GABA‐degrading enzyme GABA‐transaminase (GABA‐T). GABAergic markers are found in neurons identical in morphology and distribution to Golgi‐impregnated aspiny and sparsely spiny nonpyramidal neurons with locally arborizing axons and appear to label most if not all of the nonpyramidal neurons. In addition, the GABAergic markers are found in punctate structures in a distribution characteristic of presumed inhibitory terminals. The spine‐laden pyramidal neurons, the principal projecting cell type in the dorsal cortex, are devoid of labelling for GABAergic markers but are surrounded by presumed GABAergic terminals. The data complement previous physiological and ultrastructural studies that implicate aspiny and sparsely spiny nonpyramidal neurons as mediators of intrinsic inhibition of pyramidal neurons in turtle cortex. The results also suggest similarities in the functional organization of intrinsic inhibitory elements in turtle and mammalian cortex.
Somatostatin‐like immunoreactivity in the midbrain of the cat
Authors: Spangler Kevin M. , Morley Barbara J. 
Published: January 2005

AbstractSomatostatin (SS) immunoreactivity was localized in cat brain sections with an immunoperoxidase technique. Cell bodies in the midbrain containing SS immunoreactivity were found in the superficial and intermediate gray layers of the superior colliculus, the interpeduncular nucleus, the raphe, the inferior colliculus and nucleus of its brachium, the nucleus of the optic tract, and the lateral tegmental field. Additional positive neurons were seen in the parabigeminal nucleus and in the dorsal periaqueductal gray in kitten material. Immunoreactive fibers were observed in the periaqueductal gray and in the midbrain tegmentum, with particularly dense labeling just dorsal to the substantia nigra and in the parabrachial nuclei. This is the first report of the distribution of SS immunoreactivity in the midbrain of the cat. It is concluded that somatostatin has a distribution compatible with a role as a major neurotransmitter/neuromodulator within oertain midbrain nuclei, especially the interpeduncular nucleus and the superior colliculus.