bluuebunny/crossref_metadata_2025_split huggingface dataset:
Striate cortex and visual acuity functions in the cat
Authors: Berkley M. A. , Sprague J. M. 
Published: January 2005

AbstractUsing a two‐choice visual discrimination paradigm, thresholds for size (gratings), parallelness (parallel vs. non‐parallel lines), contour alignment (vernier offset), and angularity (polygon figures) were behaviorally determined in cats before and after ablations of portions of the geniculo‐cortical system.Animals with a total loss of cortical area 17, and with a loss, in some cases, of up to 90% of area 18 (with and without infringement into area 19), showed about a 30% reduction in grating acuity, a three‐fold increase in parallelness and angularity thresholds, and a total loss of contour alignment ability. Control animals with ablations sparing area 17 showed no significant threshold changes. All animals were able to learn classic form discriminations postoperatively, but those with area 17‐18 lesions at a somewhat slower than normal rate. Control procedures indicated that all tested discrimination capabilities did not depend on luminance differences between targets, local flux cues within the targets, or on the animals' use of residual portions of area 17 representing the peripheral visual field.Since the cat has multiple thalamo‐cortical visual pathways, the results of the present study are consistent with the hypothesis that pathways parallel to the geniculo‐striate system are capable of processing spatial information of considerable detail. The results also suggest, however, that the geniculo‐striate system is uniquely necessary for the processing of the finest attributes of spatial contours.
Regional topography within noradrenergic locus coeruleus as revealed by retrograde transport of horseradish peroxidase
Authors: Mason Stephen T. , Fibiger Hans C. 
Published: January 2005

AbstractA hitherto unsuspected degree of regional topographic organization in the noradrenergic nucleus, locus coeruleus, was revealed by the use of retrograde transport of horseradish peroxidase (HRP) from terminal areas receiving noradrenergic innervation. HRP was injected into hippocampus, hypothalamus, thalamus, caudate‐putamen, septum, amygdala‐piriform cortex, cerebellum and cortex. Successful transport was obtained from all areas, including the caudate‐putamen and cerebral cortex. The pattern of HRP positive cells in the ipsilateral locus coeruleus was markedly different depending on the location of the HRP injection. Thus, hippocampal injections labeled cells i the dorsal locus coeruleus but not at all in the ventral tip. Injections of HRP into caudate‐putamen or cerebellum labeled the ventral tip along with the rest of the dorsal portion. HRP injections into the septum labeled cells only in the dorsal half of the dorsal locus coeruleus. There thus exists a three tier division of locus coeruleus into the ventral one third, dorsal one third and intermediate one third. A further division was seen in the anterior‐posterior plane with HRP injections into the thalamus labeling the posterior pole of locus very intensely but with little transport to more anterior levels; conversely HRP injection into the hypothalamus resulted in intense labeling only in the anterior pole of locus coeruleus. Amygdala‐piriform cortex HRP injections revealed a further pattern with very intensely reactive cells scattered sparsely throughout the nucleus. Cortical HRP injections yielded weaker lebeling also in occasional, scattered cells. All HRP transport to locus coeruleus was shown to be noradrenergic by degeneration with 6‐hydroxydopamine and due to terminal, rather than fiber of passage, uptake by control injection into the dorsal NA bundle. It is concluded that the locus coeruleus is not an homogenous nucleus with respect to the origin of the noradrenergic projections to sundry forebrain, spinal and cerebellar areas, but is comprised of distinct subdivisions of noradrenergic neurons.
The afferent connections and laminar distribution of cells in the cat striate cortex
Authors: Henry G. H. , Harvey A. R. , Lund J. S. 
Published: January 2005

AbstractA laminar distribution of different functional cell types in the striate cortex of the cat is drawn up from the visual responses of single cells recorded in 64 electrode penetrations in 38 cats. In summary, S cells were found to be concentrated in laminae 4 and 6; SH cells in laminae 2, 3 and 4; C cells in laminae 5 and lower 3; B cells in laminae 3 and upper 5 and cells with non‐oriented receptive fields in lamina 4.In addition, the nature of afferent innervation to striate neurons was derived from the latency of the orthodromic response to electrical stimulation in the optic chiasm and optic radiations in 19 cats. An analysis of latency values allowed the afferent innervation to a cell to be classed as belonging either to fast or slow conducting streams in the population of dLGN axons and also permitted a decision to be made on whether or not the afferent path passed directly to the cell. Direct afferent innervation from the dLGN was not found to be confined to a single class of striate neuron. Instead, examples of cells with S, SH, C, B and non‐oriented receptive fields all had orthodromic latencies that met the requirement for direct innervation. Instances of cells with orthodromic latencies suggestive of indirect innervation were also found for most receptive field classes but these cells were encontered less frequently than those with a direct afferent input. It is argud that a variety of different cell types may act as first order neurons in the striate cortex and that cells occurring at later stages in the sequence of cortical processing may have been incompletely studied because they are more difficult to stimulate either visually or electrically.
The distribution of oxytocin‐ and neurophysin‐stained fibers in the spinal cord of the rat and monkey
Authors: Swanson L. W. , McKellar S. 
Published: January 2005

AbstractImmunohistochemical methods have been used to describe the distribution of neurophysin I‐ and oxytocin‐stained fibers in the spinal cord. In albino rats of either sex, such fibers descend through the dorsal part of the lateral funiculus to the caudal end of the cord. Fibers leave the lateral funiculus to innervate the marginal zone of the dorsal horn at all levels, and the intermediolateral column at thoracic, lumbar and sacral levels. Some fibers course medially through the intermediate gray to end in the central gray, which is innervated at all levels, and also appears to be innervated by fibers descending in the central gray itself. A semiquantitative analysis shows that the density of terminal fields in the intermediolateral column, marginal zone, and central gray varies significantly at different levels. The intermediolateral column is preferentially innervated between T1‐T3, T9‐T11, and T13‐L2. The nucleus intercalatus spinalis and the dorsal commissural nucleus (between T13 and L2), both of which contain preganglionic neurons, are densely innervated.In the monkey (Macaca fascicularis), neurophysin I‐ and oxytocin‐stained fibers descend through the lateral funiculus to the filum terminale, where some of them enter the pia‐arachnoid surrounding the filum. The intermediolateral column is not innervated between T1‐T3, is sparsely innervated at sacral levels, and is moderately innervated between T4 and L3; the greatest density of fibers occurs at L3. At most levels, few if any fibers are found in the central gray and marginal zone; the central gray is sparsely innervated between T8 and L2, at S2, and between Co3‐Co6, and the marginal zone contains a small number of fibers in the region of S2 and Co6.Neurophysin I‐ and oxytocin‐stained fibers were also found in the intermediolateral column, marginal zone, and central gray of homozygous Brattleboro, spontaneously hypertensive, and Egyptian sand rats.The results suggest that the paraventriculo‐spinal pathway is particularly related to specific groups of sympathetic and parasympathetic preganglionic neurons, and to the marginal zone, which is involved in the relay of ascending nociceptive information through the spinothalamic tract.
Commissural columns in the sensory‐motor cortex of monkeys
Authors: Jones E. G. , Coulter J. D. , Wise S. P. 
Published: January 2005

AbstractCallosally projecting cells and the terminal ramifications of their axons were identified in the monkey sensory‐motor cortex by retrograde and anterograde labeling techniques, often by double labeling cells and axons in the same animal.Bundles of callosal fibers terminate in small column‐like zones 0.5‐1 mm wide in the motor cortex (area 4) and in the first (SI) and second (SII) somatic sensory areas. Such columns are aligned in register to form elongated strips extending mediolaterally in the long axes of the pre‐ and postcentral gyri. Significant portions of area 4, SI and SII, in regions corresponding to the representations of the hand and foot, are not callosally connected.The cells of origin of callosal fibers in SI are largely confined to layer IIIB and form columns and strips corresponding to the above. In connected zones of SI, the callosal connection is reciprocal and precisely point‐to‐point. This and the laminar distribution of the terminal ramifications of callosal fibers (to layers I‐IV) suggest that callosal fibers may arise from and terminate upon exactly homotopic, column‐like groups of layer IIIB pyramidal cells.Commissurally projecting cells and their terminal ramifications are not limited to particular architectonic fields or particular parts of fields in SI. All architectonic fields of SI project heterotopically to the contralateral SII.
An electron microscope study of synaptic contacts in the abdominal ganglion of Aplysia californica
Authors: Tremblay J. P. , Colonnier M. , McLennan H. 
Published: January 2005

AbstractThe fine structure of the abdominal ganglion of Aplysia californica has been studied in preparations fixed by immersion in aldehydes, either directly or after a survival of a few hours in artificial sea water. The central core of neuropil is surrounded by a rind of neuronal cell bodies floating in a subcapsular space containing a loose mesh work of neuronal and glial processes, separated by wide extracellular spaces. Large primary processes with deeply infolded membranes leave the neuronal perikarya and enter the neuropil where they branch into smaller processes containing either neurofilaments, neurotubules or both. Some have the appearance of initial segments. The neuropil is not a homogenous structure. Rather, four types of zones can be distinguished: (1) zones of fibers of passage coursing together in the neuropil and making few synaptic contacts; (2) zones of neurosecretory fibers containing large granules and dense‐core vesicles, again making few synaptic contacts; (3) zones with a great variety of synaptic contacts between medium size and small profiles; and (4) glomerular zones. The differentiated membranes of the synapses are characterized by a slight increase in density and by being regularly parallel to each other. Presynaptic densities are sometimes quite prominent but specialized dense cytoplasmic opacities have never been seen bordering the postsynaptic membranes, i.e., all synapses are of the symmetrical type. Interlemmal opacities vary considerably in density. In zone 3, the synaptic vesicles are of several sizes, are round, oval or flat, and are either clear or filled with different types of dense material. The population of vesicles within a single profile may consist either of a homogeneous group of similar vesicles, or of various mixtures of two or three kinds of vesicles. In profiles with mixtures of clear and large dense‐core vesicles, it is often only the clear vesicles which agglomerate towards the differentiated membranes. In such cases the large dense‐core vesicles lie as a peripheral halo around the clear vesicles. Here, and especially in other large neuronal profiles not forming contact in the plane of section, they can be seen to associate specifically with mitochondria and glycogen. It is proposed that they do not contain neurotransmitters but are related to mitochondrial activities such as the strorage of ATP or the movement of calcium ions. In profiles with mixtures of clear and small dense‐core vesicles, both types of vesicles often touch the presynaptic membrane, suggesting the release of two transmitters or of a modulator or neurohormone with a transmitter, by a single terminal. Serial synapses are present in this zone. The glomerular zones contain small profiles forming many synaptic contacts, some of which are arranged in such a way as to suggest the existence of “reciprocal” serial synapses.
Spiral ganglion cell counts in an age‐graded series of rat cochleas
Authors: Keithley Elizabeth M. , Feldman Martin L. 
Published: January 2005

AbstractSpiral ganglion cells in the cochleas of Sprague‐Dawley rats in various age groups were counted in order to assess the extent and location of cell degeneration with age. Cells in every tenth section of serially sectioned plastic embedded cochleas were counted in the light microscope. The median cell number for the 1‐ to 2‐month‐old animals was 15,800 cells. This number was first seen to be significantly reduced ( −14%) in the 23‐ month‐old animals. At 27 to 29 months the ganglion cell number was reduced' by 20%, while at 33 to 34 months there was a 17% loss. Losses were found throughout the length of the ganglion with the greatest losses at the lower basal and apical ends. In the oldest group, these losses amounted to 28% and 33%, respectively.Type II ganglion cells first showed a significant decrease in number in the 27 ‐ to 29‐month‐old group, when a 32% loss was seen. The same loss was seen in the 33‐ to 34‐month‐old group. Unlike the type I cells which are lost throughout the length of the ganglion, type II cells were not significantly reduced in number at the basal end, but decreased by as much as 42% in the middle and apical regions.
Development of the diencephalon in the rat. IV. Quantitative study of the time of origin of neurons and the internuclear chronological gradients in the thalamus
Authors: Altman Joseph , Bayer Shirley A. 
Published: January 2005

AbstractGroups of pregnant rats were injected with two successive daily doses of 3H‐thymidine from gestational days 13 and 14 (E13 + 14) until the day before birth (E21 + 22). With this progressively delayed comprehensive labelling procedure we determined the time of origin of neurons in the nuclei of the epithalamus, thalamus, and ventral thalamus. The zona incerta, subthalamic nucleus, are composed of the earliest arising neurons (E13, or before, to E15). The neurons of the lateral habenular nucleus are produced between days E13–16. The neurons of the medial geniculate and lateral geniculate nuclei, the ventrobasal and ventrolateral complexes, and the nucleus lateralis, pars posterior, arise rapidly on days E14–15; the medial geniculate nucleus with a peak on day E14, the others with a peak on day E15. Neurons of a group of nuclei, with ill‐defined boundaries medial to the sensory relay nuclei, arise apparently on days E15–16, with a peak on day E15; these may represent the intralaminar nuclei. The next group is generated on days E15–16 but with peak formation time on day E16: this includes the anteroventral, anterodorsal, anteromedial and mediodorsal nuclei. The rhomboid, reuniens and paratenial nuclei, and the paraventricular nucleus, pars anterior, arise next (E16–17). The medial habenular nucleus forms last and over a protracted period (E15–19). With their lengthy generation time the lateral and medial habenular nuclei resemble more the nuclei of the hypothalamus than the nuclei of the dorsal thalamus.
An autoradiographic study of the retinal projection in Xenopus laevis with comparisons to Rana
Authors: Levine R. L. 
Published: January 2005

AbstractThe retinal projection to the brain in Xenopus has been examined using autoradiographic techniques. The labelled moieties used were 3H‐proline and 3H‐fucose.There are three anterior thalamic optic terminal sites in Xenopus. These are the nucleus of Bellonci, the corpus geniculatum thalamicum and the rostral visual nucleus. The first two of these are similar to the homonymous nuclei in Rana while the last, the rostral visual nucleus, appears to correspond to the rostral end of the posterior entopeduncular nucleus of Rana. Both the nucleus of Bellonci and the rostral visual nucleus receive strong ipsilateral retinal inputs while the corpus geniculatum receives only a weak ipsilateral projection. In the posterior thalamic: pretectal region there is only one clearly defined optic terminal nucleus—the uncinate field. This structure receives a strong ipsilateral input. In addition there are two other labelled fields in this region whose nature (fibers v. terminals) cannot be clearly discerned in autoradiographs. These are the thalamopretectal field—a horizontal band which extends in the dorsomedial neuropil from midthalamus to the pretectum, and the pretectal field where diffuse labelling is evident, especially ipsilateral to the injected eye. The thalamopretectal field also receives an ipsilateral input. The optic tectum in Xenopus receives a dense contralateral retinal innervation but only a weak ipsilateral projection. Finally, the basal optic nucleus receives both contralateral and ipsilateral retinal innervation with the latter being, by far, the weaker of the two.In addition to other differences between the two species, it is obvious that there is a much denser and more extensive ipsilateral retinal projection to the thalamic and pretectal brain structures in Xenopus than in Rana. This is presumably due to the greater size of the binocular field in Xenopus.
Coronate cells: Displaced amacrines of the rabbit retina?
Authors: Hughes A. , Vaney David I. 
Published: January 2005

AbstractThe rabbit retinal ganglion cell layer contains a soma population which is morphologically distinct from the demonstrated ganglion cells. These “coronate cells” (Vaney, '80) have many features in common with classical neurons and are qualitatively different from typical glial cells. Detailed investigation by specific staining, ribonuclease treatment, and electron microscopy indicates that coronate cells are microneurons. The coronate cells contain somatic subsurface cisternae typical of rabbit amacrine cells, and are similar in appearance to some neurons of the amacrine cell layer. It is suggested that they represent, at least in part, a population of “displaced” amacrine cells.
Mapping the normal and regenerating retinotectal projection of goldfish with autoradiographic methods
Authors: Meyer Ronald L. 
Published: January 2005

AbstractIn normal goldfish, lesions of various size were made in nasal or temporal retina immediately prior to retinal labeling with tritiated proline. The resulting gaps in retinal innervation of tectum indicated that the projection is retinotopographically ordered to a precision of about 50 μm. Similarly, acute tectal incisions transecting the optic pathways were combined with immediate retinal labeling. The resulting tectal denervation confirmed that most fibers follow highly ordered paths through the stratum opticum of tectum; but a few fibers were found to follow unusual paths to their appropriate tectal positions. In other fish, the optic nerve was crushed. At various times afterwards, retinotopography and pathway order were similarly analyzed by making retinal lesions or tectal incisions just prior to labeling. For up to 40 days after crush, the projection lacked any refined retinotopic order. Only a gross topography could be demonstrated. Over several months, retinotopography gradually improved eventually approaching that of normals. Correlated with this was an initial stereotypic growth through the pathways of the stratum opticum followed by a long period of highly anomalous growth through the innervation layer. Evidently, many regenerated fibers grew in through inappropriate routes to the wrong region of tectum but subsequently arrived at their appropriate locus by circuitous routes within the innervation layer.
The growth of segmental nerves from the brachial myotomes into the proximal muscles of the chick forelimb during development
Authors: Bennett M. R. , Davey D. F. , Uebel K. E. 
Published: January 2005

AbstractA study has been made of the growth of segmental nerves 13 to 16 (SN 13 to SN 16) into the chick limb bud, from the time when they have just reached the ends of the brachial myotomes (stage 21: Hamburger and Hamilton, '51), until they enter the newly formed ventral (stage 24) and dorsal (stage 25) pre‐muscle cell masses in the limb bud. At stage 22 axon bundles of SN 13 to SN 16 have grown off the ends of their respective myotomes, and converge towards the most densely packed mesenchyme in the limb bud at segmental level 15. As a consequence, the first axon bundles of SN 14 and SN 16 have almost joined those of SN 15, whereas the further removed SN 13 axon bundles have not yet reached the level of SN 15. By stage 23 the first axon bundles from SN 14 to SN 16 have joined at segmental level 15 to form a nerve which grows toward the ventral pre‐muscle cell mass. At stage 24 axon bundles from SN 13 have joined those from SN 14 to SN 16 to form the brachialis longus inferior nerve, which enters the densest region of the ventral pre‐muscle. Other axons from SN 13 to SN 15 grow along the pathways provided by the early arriving axon bundles towards the ventral pre‐muscle, but diverage from those at segmental level 14 to grow to the dorsal pre‐muscle. By stage 25 axon bundles from SN 13 to SN 15 have joined to form the brachialis longus superior nerve which enters the densest region of the dorsal pre‐muscle. At stage 26 a plexus has formed due to this pattern of growth of the segmental nerves between stages 22 and 25. It is suggested that pre‐muscle cells synthesize a nerve growth factor which directs the growth of axons into the limb bud.
Neurons of the periaqueductal gray matter as revealed by Golgi study
Authors: Liu Rita P. C. , Hamilton Betty L. 
Published: January 2005

AbstractNeurons of the periaqueductal gray matter of the normal adult cat are classified into seven general types, Ia, Ib, II, IIIa, IIIb, IIIc, and IIId, based on the Golgi‐Cox impregnated materials. Types Ia and Ib are spindle shaped bipolar neurons with one straight dendritic process forming varicosities and short stemmed spines. Type Ia is small in size and Ib is larger. The axon of each neuron emerges from another pole and projects beyond the PAG region. Occasionally it may share the origin with a dendrite or a tuft of dendrites. Type II, triangular shaped, has an apical dendrite that traverses a long distance within the PAG and an axon emerging from the basal portion and projecting beyond the PAG. Type IIIa, b, c, and d are pleomorphic multipolar neurons. Type IIIa has a rhomboid‐shaped soma and dichotomically branching dendrites. Type IIIb has a spheroidal soma and short axons that terminate within the PAG. Type IIIc has a piriform soma and spiny dendrites that ramify perfusely and an axon which terminates within the PAG. Type IIId has the largest soma of all these neurons and the structure resembles an undifferentiated motor neuron of the CNS. Axons of the types IIIa and IIId are projecting in nature. Type Ia is found exclusively in the area immediately surrounding the aqueduct, the nucleus medialis. Types IIIc and IIId are found exclusively in the lateral region of the PAG which corresponds to the nucleus lateralis while the remaining cell types are found mostly in nuclei lateralis and dorsalis.