bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of visual deprivation and alterations in binocular competition on responses of striate cortex neurons in the cat
Authors: Kratz Kenneth E. , Spear Peter D. 
Published: May 2005

AbstractElectrophysiological recordings were made from single neurons in striate cortex of normally reared kittens (group N), kittens raised with binocular lid‐suture (group BD), and kittens raised with one eye lid‐sutured and the other eye removed (group MD‐E). The MD‐E group represents a condition in which inputs from the deprived eye have been placed at a competitive advantage over those from the other eye.In agreement with previous studies, fewer cells were responsive to visual stimulation in BD kittens than in N kittens. Among the responsive cells, fewer were direction selective, fewer were orientation selective, and more had inconsistent or fast‐adapting responses than in normals. The responsiveness and receptive field properties of striate cortex neurons in the MD‐E kittens were less affected by the visual deprivation than in BD kittens; however, they still were abnormal in comparison to normal kittens.Comparison of the ocular dominance distributions for cells in N and BD kittens showed a marked reduction in binocularly driven cells in BD kittens. In addition, in BD kittens, a larger proportion of monocularly driven cells had orientation selective receptive fields than did binocularly driven cells. This difference was not found in normally reared kittens.The results of this study suggest that abnormal binocular interactions contribute to the effects of visual deprivation following binocular lid‐suture, probably due to asynchronous light‐dark inputs through the closed lids. Removing the other eye and placing inputs from the deprived eye at a competitive advantage during development results in decreased effects on striate cortex neurons. Nevertheless, visual deprivation still produces abnormalities in striate cortex independent of asynchronous or uncorrelated visual stimulation of the two eyes.
Selective uptake and transport of label within three identified neuronal systems after injection of 3H‐GABA into the pigeon optic tectum: An autoradiographic and golgi study
Authors: Hunt S. P. , Künzle H. 
Published: May 2005

AbstractAfter injection of tritiated gamma‐aminobutyric acid (GABA) into the pigeon optic tectum and thalamus it was possible to correlate certain aspects of the autoradiographic labelling pattern with observations made from Golgi material. Three neuronal, GABA specific systems were identified both from the uptake of the amino acid and from the subsequent and bidirectional intracellular transport of label.The first system derives from cell bodies within sublayer IIi the axons of which could be selectively labelled throughout their course within layer I and to the areas of termination within the pretectum and ventral thalamus. The radially ascending dendrites and axon collaterals of these neurons arbourised within sublayer IIf, and could be labelled in a retrograde fashion after tectal or thalamic injections.The second system was represented by small perikarya within sublayer IIc with locally and superficially directed dendrites and with a radially and deep directed axon from which an extensive axon collateral system arose. It was found possible to label these perikarya either directly or indirectly after tangential tectal injections which preferentially labelled the axons and terminals of these neurons within the deeper regions of the tectal cortex and resulted in the retrograde axonal movement of label to the overlying cell bodies.A third system was found within sublayer IId, was horizontally organized and from a correlation with degeneration, other autoradiographic and Golgi preparations thought to be mainly dendritic in nature.The biochemical and anatomical implications of specific GABA uptake and subsequent transport of label are discussed and a model of the tectal cortex, based on the three proposed inhibitory systems and their relation to a number of tectal afferent inputs, considered.
Electron‐microscopic identification of Marchi‐positive bodies and argyrophilic granules in the spinal cord white matter of the guinea pig
Authors: Hildebrand Claes , Aldskogius Håkan 
Published: May 2005

AbstractSections from spinal cord white matter of normal and rhizotomized guinea pigs fixed by glutaraldehyde perfusion were stained with Marchi fluid or according to a suppressive silver technique. With the aid of the section‐embedding method thin sections, cut from light‐microscopically identified areas containing Marchi‐positive bodies or argyrophilic granules, were examined in the electron microscope.The results show that the Marchi‐positive bodies and argyrophilic granules, which are present in normal white matter, represent different histochemical expressions of the same entity — the myelinoid body. In view of the similarities between myelinoid bodies and myelin fragments formed during Wallerian degeneration it is suggested that this type of so called artifact staining of normal white matter inherent to both methods should instead be considered as an expression of a specificity of the two methods for degenerating nervous elements.
Structural and functional changes in an identified cricket neuron after separation from the soma. II. Functional changes
Authors: Clark Richard D. 
Published: May 2005

AbstractPhysiological and behavioral effects of separation from the soma were examined in isolated arborization and isolated axon segments of an identified motor neuron in the Polynesian field cricket, Teleogryllus oceanicus. The identified neuron, the contralateral dorsal longitudinal motor neuron of the metathoracic ganglion (CDLM), has an arborization most of which lies contralateral to its soma within the ganglion. Midline lesions in the ganglion separated CDLM into a distal segment composed of the axon and most of the arborization, and a proximal segment made up of the remaining arborization, neurite and soma. Isolated axonal segments were produced by cutting the nerve containing the CDLM axon.The function of the neuron‐muscle system composed of CDLM, its pre‐synaptic inputs, and its innervated muscle bundle was examined in control and experimentally operated animals. Extracellular recording assessed function in the axon. Electrical or tactile stimulation was used to excite pre‐synaptic inputs to the CDLM arborization. Intracellular recording determined changes in postsynaptic potentials and miniature end‐plate potentials in the muscle bundle innervated by CDLM.Normal axonal conduction, competence to respond to pre‐synaptic input, neuron‐muscle transmission, and miniature end‐plate potential appearance can remain in the isolated arborization preparation. Physiological viability is longer in the cricket isolated arborization than in other insect distal segments described. Survival times of axonal conduction and the competence of the isolated arborization to respond to pre‐synaptic input are roughly correlated with disappearance of the whole distal segment at 100 or more postoperative days. A naturally‐occurring breakdown of the metathoracic dorsal longitudinal muscles in Teleogryllus eventually prevents measurements of post‐synaptic potentials and miniature end‐plate potentials. Normal post‐synaptic function mediated by the distal arborization is maintained up to this breakdown, to a maximum of 44 days postoperative.The distal axonal segment of CDLM degenerates physiologically within four days postoperative, a time course approximating that of degeneration in vertebrate peripheral nerve distal axons.
Developmental studies of thalamocortical and commissural connections in the rat somatic sensory cortex
Authors: Wise S. P. , Jones E. G. 
Published: May 2005

AbstractAutoradiographic, axonal degeneration, and horseradish peroxidase fiber tracing methods were employed to investigate the organization, development and potential plasticity of the thalamocortical projection to the somatic sensory cortex of the rat. In the adult animal, thalamocortical terminals are concentrated primarily in layers I and IV and in the upper part of layer VI. Fibers terminating in layers IV and VI arise from a different thalamic region than those terminating in layer I. Discrete clusters of fibers and terminals 250–450 μm wide are distributed only to the parts of the SI cortex containing dense aggregates of layer IV granule cells and not to the intervening, less granular and commissurally connected zones.At birth, thalamocortical fibers have invaded the deep part of the developing SI cortex and are concentrated in the upper part of layer VI. Between the age of two and three days, an additional concentration of fibers appears in the part of the cortical plate which will become layer IV. Layer IV is clearly recognizable by three days of age and the dense granule cell aggregates appear in it no more than one day later. The ingrowth of commissural fibers (Wise and Jones, '76) lags behind that of thalamic fibers. The mature commissural fiber pattern is not established until the age of seven days.After removal of the developing thalamocortical system by thalamotomy in newborn rats, subsequent investigation of the commissural system in the adult showed that no commissural fibers or terminals had invaded either laminae or zones of the cortex deprived of thalamic input. Similarly, commissurotomy at birth was not followed by sprouting of thalamic fibers into zones or laminae deprived of commissural connections. The connectional specificity observed in these neocortical fiber systems contrasts markedly with the plasticity of connections reported in allocortical systems.Removal of thalamocortical afferents before they attain their definitive distribution does not radically effect the overall development of the dense granule cell aggregates in layer IV. Within the aggregates, however, subsidiary features such as the “barrels” fail to appear. This finding suggests that certain elements of cortical architecture such as the dense granule cell aggregates are independent of thalamic afferents while others, such as the barrels, result from the interaction of the developing thalamocortical fibers and/or terminals with maturing neurons.
A neuroanatomical study of the cochlea of the little brown bat (Myotis lucifugus)
Authors: Ramprashad Fred , Money Kenneth E. , Landolt Jack P. , Laufer Jerry 
Published: May 2005

AbstractThe population and density of the bipolar ganglion cells and sensory hair cells were determined from serial sections and graphic reconstructions of the cochlea and spiral ganglion of four little brown bats. The spiral ganglion lacks a bony canal and is a one and one‐half turn spiral of almost uniform thickness which ends in a broad flat nodule at its apex. The average length of the nerve cell body is 7.4 μ (range: 5–15 μ) and it is 6.4 μ wide (5–10 μ). The average number of ganglion cells enumerated was 63.2 × 103 (range: 60.6 × 103–65.2 × 103) and following correction for “split cell error,” the total number was 55.3 × 103 ganglion cells. The ganglion cell density curve increases gradually to a maximum value of 11.7 × 103 cells/mm2 at 2.4–3.2 mm from the basal end. The two and one‐half turn cochlea is 6.9 mm long (6.8–7.1 mm) with an estimated total of 700 inner and 2,800 outer sensory hair cells. The densities of outer and inner hair cells increase from the base to the apex by 21% and 32%, respectively. However, the density of sensory cells per unit of sensory epithelium decreases from base to apex. The ratio increases to a maximum value of 22:1 at 2.4 mm and then declines toward the apex. The significance of these findings is discussed and compared to similar studies on other high‐frequency hearing mammals.
A quantitative analysis of the innervation of the pulp of the cat's canine tooth
Authors: Beasley W. L. , Holland G. R. 
Published: May 2005

AbstractAlthough the cat's canine tooth has become the accepted model for the electrophysiological study of dental sensory mechanisms no examination of its innervation has been carried out at the electron‐microscopical level. This study looked at the number and size distribution of both myelinated and non‐my‐elinated fibers in the crown of the cat's canine. The material examined was prepared by routine methods and the measurements taken from electron‐microscopical montages of pulpal cross‐sections. The measurements were made using a Quantimet 720 image analysis system. In one complete cross‐section 3,470 fibers were counted. Eighty‐one percent of these were non‐myelinated with a modal diameter of 0.35 μm. The modal diameter of the myelinated fibers was 2.5 μm. The relative preponderance of non‐myelinated fibers increased from core to periphery. The largest myelinated fibers were concentrated in the core. The fiber size distribution was similar in the single complete and two partial sections examined. It is concluded that all the fibers in the crown of the cat's canine would be contained in the A‐delta and C groups and that the strikingly large number of fibers present suggests that the peripheral pulp has a dense innervation, many of the cell processes found there being unsheathed axons.
Histochemical evidence for a post‐lesion reorganization of cholinergic afferents in the hippocampal formation of the mature cat
Authors: Steward Oswald , Messenheimer John A. 
Published: May 2005

AbstractWe have utilized acetylcholinesterase (AChE) histochemistry to analyze possible post‐lesion changes in the distribution of AChE containing afferents to the hippocampal formation of the cat following unilateral destruction of the entorhinal cortex. In the cat, the entorhinal area gives rise to a massive projection to the ipsilateral fascia dentata, and to regio inferior and regio superior of the hippocampus proper. Sixty days following unilateral entorhinal lesions, histochemical preparations for AChE indicate a dramatic increase in the density of the reaction product in the zones normally occupied by entorhinal afferents in the fascia dentata and regio inferior of the hippocampus proper, whereas little if any increase in the density of the reaction product was observed in the entorhinal terminal zone in regio superior. In addition to these increases in the density of the AChE reaction product, there was also evidence for a widening of an AChE free zone in the inner stratum moleculare of the fascia dentata denervated by the lesion. The time course of these changes in the pattern of AChE staining was analyzed by sacrificing animals 7, 10, 13, 14, 16, 17, 19, and 20 days following entorhinal cortical lesions. The increase in the density of the AChE reaction product in the denervated zones was not apparent at seven days post‐lesion, while at ten days post‐lesion, a slight increase in the density of the AChE reaction product could be observed. By 13 days post‐lesion, the differences between the denervated and normally innervated (contralateral) hippocampal formation were prominent, and by 16 days post‐lesion, the pattern of staining appeared comparable to that which was observed at longer post‐lesion intervals. The present experiments indicate that following entorhinal cortical lesions in mature cats the final post‐lesion pattern of altered AChE staining is quite comparable to that which is observed following similar lesions in rats. In the rat, such changes in AChE staining have been interpreted as a reflection of a proliferation of cholinergic septal afferents within the denervated zones. If this interpretation is correct, the present results suggest a similar proliferation of cholinergic afferents following entorhinal lesions in cats. The time course of this apparent proliferation is considerably slower in the cat then in the rat, however, since the earliest changes are observed at approximately five days post‐lesion in the rat, and ten days post‐lesion in the cat.
The effect of refeeding after neonatal starvation on purkinje cell dendritic growth in the rat
Authors: McConnell P. , Berry M. 
Published: May 2005

AbstractMale rats, undernourished from birth until 30 days by restricting access to the lactating dam, were given ad libitum food supplies until 80 days. Body weight, whole brain weight and cerebellar weight remained significantly lower in these animals than in normally fed controls. Significant deficits in the area of the molecular and granular layers persisted at 80 days, although there was some recovery during the refeeding period. At the same time granule and Purkinje cell density declined, suggesting that the areal recovery was due to the expansion of the interneuronal matrix. Granule cell numbers remained unchanged between 30 and 80 days.Network analysis of Golgi‐Cox preparations indicated a 28% decrease in overall size of the Purkinje cell dendritic networks, due primarily to a deficit in segment frequency which remained unchanged throughout the rehabilitation period. Segment length did, however, show some recovery; distal segments from 80‐day experimental networks were significantly longer than those of 30‐day undernourished animals. The results of the topological analysis suggested that dendritic remodelling had taken place during the rehabilitation period.The failure to observe a complete recovery in the size and morphology of the dendritic network may be explained in terms of recent suggestions that dendritic development is influenced both by the metabolism of the neurons themselves, and by the number and density of adjacent afferent axons. It is suggested that refeeding from 30 days leads to the recovery of Purkinje cell metabolism, but is unable to restore the parallel fiber deficit.
Abnormalities of the cortico‐geniculate pathway in siamese cats
Authors: Montero V. M. , Guillery R. W. 
Published: May 2005

AbstractThe cortico‐geniculate pathways of normally‐pigmented and Siamese cats have been studied by autoradiography following injections of 3H proline into cortical area 17. Normal Siamese cats and Siamese cats that were raised with one eye sutured or removed have been compared with normally‐pigmented cats treated in the same manner. The cortico‐geniculate projection from area 17 passes to all parts of the lateral geniculate nucleus in normal cats and distributes to all geniculate layers (Updyke, '76). This distribution was essentially unaffected by an early monocular suture or enucleation. In Siamese cats, the cortico‐geniculate projection to lamina A and to the lateral normal segment of lamina A1 was normal, but little or no label was seen in the abnormal segment of lamina A1. The interlaminar zones adjacent to the abnormal segment of lamina A1 were densely filled with label, as though the cortico‐geniculate axons avoid this segment. Unilateral enucleation or lid‐suture did not affect this distribution, suggesting that it does not depend upon visual experience. These Siamese cats were all identified by electrophysiological studies as having a normal topography of the geniculo‐cortical pathways. That is, they were “Midwestern” cats.
The sensory trigeminal system of a snake in the possession of infrared receptors. II. the central projections of the trigeminal nerve
Authors: Molenaar Gerard J. 
Published: May 2005

AbstractThe central projections of the sensory roots of the trigeminal nerve in Python reticulatus have been studied by means of the Fink Heimer technique following transsection of these roots between the trigeminal ganglia and the brainstem.The sensory trigeminal fibres are distributed to the two separate sensory trigeminal systems, described before, i.e., the common sensory and the lateral descending trigeminal system. The projections of the three peripheral trigeminal branches are restricted to their own territories of the various tracts and nuclei. Generally, the ophthalmic root projects most ventrally; the mandibular root most dorsally and the maxillary root intermediately. The ophthalmic branch descends until the level of the first cervical nerve root, the maxillary and mandibular branches proceed beyond the second cervical nerve roots.The distribution pattern of the sensory trigeminal fibres differs in two major aspects from that of other vertebrates. The first difference is a large overlap of the projection areas from the mandibular and maxillary roots. The probable occurrence of this overlap within other, mammalian, species is discussed. The second major difference is the projection into the lateral descending trigeminal nucleus. The morphology of the degenerating fibres and “boutons terminaux” in this lateral descending system is markedly different from that within the common sensory system.Preliminary notes are presented to show that the common sensory and the lateral descending systems project to different areas in the mesencephalon and diencephalon. It will also be shown that the nucleus of the lateral descending trigeminal tract is exclusively concerned in processing the infrared information relayed by the pit organs.The possibility of the presence of a separate trigeminal system in other vertebrates, equivalent to the lateral descending trigeminal system of the python, is discussed.
Estimate of the number of myelinated axons in the cat's optic nerve
Authors: Stone Jonathan , Campion Joyce E. 
Published: May 2005

AbstractThe number of myelinated axons in the cat's optic nerve has been estimated from a partial count of sections of the nerve examined by electron microscopy. The average count obtained from four nerves was 128,600 (range 112,800‐147,200). This figure is within 10% of a previous estimate of the number of ganglion cells in the cat's retina, but is 33% lower than the only previous estimate of the number of these axons based directly on electron microscopy. Possible sources of the discrepancy are discussed.The functional implication of this total, in the context of earlier work on ganglion cell topography, are also discussed.
Altered retinal projection in brushtailed possum, trichosurus vulpecula, following removal of one eye
Authors: Sanderson K. J. , Pearson Lyn J. , Dixon Pam G. 
Published: May 2005

AbstractOne eye was removed from ten brushtailed prossums aged 18 to 102 days. The possums were kept until they reached 8‐13 months of age and the remaining eye was injected with 3H leucine to show the retinal projections. Retinal projections were also mapped in five normal possums.In the one‐eyed possums we found an altered retinal projection to the medial terminal nucleus (MTN), the dorsal lateral geniculate nucleus (LGNd) and the superior colliculus (SC). In normal possums the MTN receives an contralateral retinal projection. The LGNd has a laminar structure, there being three contralateral laminae and five ipsilateral laminae. In normal possums there is a contralateral retinal input to the superficial layers of the SC and in the front half of the SC there is an ipsilateral input top the deeper layers.In the one‐eyed possums we observed a bilateral retinal projection to the MTN. This was best developed in possums which had lost one eye at an early age (about 25 days). In the one‐eyed possums there was an extensive retinal projection to the superficial layers of the ipsilateral SC in addition to the normal retinal projection to the contralateral SC. In animals which had lost one eye at about 25 days the retinal fibers covered about three‐quarters of the ipsilateral SC, whereas in animals which had been operated at about 80 days the retinal fibers occupied only part of the front half of the ipsilateral SC. Animals which had lost one eye at about 80 days showed some growth of retinal axons into the deafferented layers of the LGNd and these layers were thinner than the layers with a normal nerve input. In animals which had lost one eye at 25 to 50 days retinal fibers form the remaining eye covered the whole of the LGNd on both sides.The possum which lost one eye at age 102 days, when its eyes were open, had retinal pathways which were nearly normal.