摘要:

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

ISSN:0092-7317    

DOI:10.1002/cne.901700202

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractThree aspects of the labelling pattern seen after the injection of 13 different radioactive amino acids into the pigeon optic tectum have been described: The efferent projections of the optic tectum; the specific labelling of two pathways; and the dendritic organisation of tectal layer III neurons based on the retrograde and anterograde movement of label within these dendrites.Discrete injections of tritiated amino acid that involved all or only the superficial tectal layers suggested that layer III gave rise to the massive non‐topographically organised and bilateral projections (fibers crossing within the decussatio supraoptica ventralis) upon the nuclei rotundus, subpraetectalis and interstitio‐praetecto‐subpraetectalis and to the ipsilaterally directed pathways terminating within the nuclei praetectalis, triangularis, subrotundus, dorsolateralis anterior thalami, posteroventralis and ventrolateralis thalami. Layer III neurons may also be the source of efferents to the posterior dorsolateral thalamus (the layer III pathway), the pontine grey and, bilaterally to the reticular formation and of the layer IV or tectal commissural pathway terminating within the contralateral tectal cortex. In contrast projections originating from layer II were generally topographically organised and terminated either within certain of the isthmic nuclei (n. isthmi pars parvocellularis, n. isthmo‐opticus and n. semilunaris) or ran within layer I (layer I pathway) to end in the pretectum (griseum tectale) and ventral thalamus (n. ventrolateralis thalami, n. geniculatus, pars ventralis). A small projection from layer II upon the ipsilateral nucleus rotundus may also be present.Tritiated serine and tyrosine were found to be particularly effective in labelling perikarya as well as axons and terminals. The layer I pathway could be selectively labelled after tectal injections of3H‐GABA while the cell bodies of Ipc neurons were labelled in a retrograde fashion after tectal injections of3H‐glycine, serine or alanine.Intrinsic tectal labelling was found by correlation with Golgi material to reflect both anterograde and retrograde transport of label within dendrites of layer III cells. Anterograde movement of label indicated that the terminal portions of layer III cell dendrites ended in an orderly radial arrangement within sublayers IIb and IId, while the retrograde movement of label resulted in the labelling of layer III perikarya outside the inje

ISSN:0092-7317    

DOI:10.1002/cne.901700203

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

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, considere

ISSN:0092-7317    

DOI:10.1002/cne.901700204

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

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

ISSN:0092-7317    

DOI:10.1002/cne.901700205

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractThe distribution and morphologies of neurons containing acetylcholinesterase (AChE, EC 3.1.1.7) in the thalamus and hypothalamus of the rat were studied by means of a pharmaco‐histochemical technique involving staining for AChE (Karnovsky‐Roots' procedure) at various times after administration ofbis‐(l‐methylethyl)phosphorofluoridate. This method enables visualization of individual AChE‐containing neuronal somata and their processes to a degree not possible with other protocols for the enzyme.The strongest AChE activity occurring at the level of the thalamus is found within the small, round to oval, somata of nucleus anterior dorsalis. Most of the intralaminar nuclei, as well as nucleus reticularis, are composed of mediumsized multipolar neurons displaying moderate to strong AChE activity. Moderately stained AChE neurons are also found in pars ventralis of nucleus geniculatus lateralis and in pars lateralis of nucleus habenularis. Most of the neurons of the lateral and posterior thalamic territories, however, are nearly devoid of AChE.At the level of the hypothalamus, the neurons of nuclei supraopticus and paraventricularis show strong AChE activity. The AChE neurons of nucleus supraopticus are surrounded by numerous AChE‐containing processes of some large lateral preoptic area neurons that stain intensely for the enzyme. Numerous intensely stained AChE perikarya occur in the lateral, dorsal, and supramammillary hypothalamic areas. These neurons often possess several AChE‐containing processes. Nuclei arcuatus and ventromedialis consist mainly of neurons displaying a weak to moderate intensity of AChE staining. At the level of the mammillary bodies most neurons show moderate AChE activity except the neuronal somata of nucleus mammillaris lateralis which stain very strongly f

ISSN:0092-7317    

DOI:10.1002/cne.901700206

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractThe retinal projections in the ringtailed possum,Pseudocheirus peregrinuswere determined using Fink‐Heimer material and autoradiography. At least seven regions in the brain receive retinal projections. These are (1) the suprachiasmatic nucleus of the hypothalamus (2) the dorsal lateral geniculate nucleus (3) the ventral lateral geniculate nucleus (4) the lateral posterior nucleus (5) the pretectum (6) the superior colliculus, and (7) the accessory optic system. The accessory optic system and lateral posterior nucleus receive a contralateral retinal projection only and the other five regions receive a bilateral retinal projection.The dorsal lateral geniculate nucleus consists of two parts: an outer α division of closely packed cells and an inner β division containing loosely scattered cells. There are no cell layers apparent within the α division in Nissl sections. The autoradiographs and Fink‐Heimer material reveal four concealed laminae within the α division. Lamina 1, which is adjacent to the optic tract and lamina 3 receive a predominantly contralateral input. Laminae 2 and 4 receive a predominantly ipsilateral input. The β segment contains a fifth lamina which receives contralateral retin

ISSN:0092-7317    

DOI:10.1002/cne.901700207

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractThis electron microscopic study indicates that the rabbit optic nerve contains 394,000 ± 20,000 (p<0.05) nerve fibres, of which at least 98% are myelinated. The fibre diameter spectrum of the nerve is unimodal and ranges from 0.25–7 μm with its peak at 0.75 μm. The projection of the visual streak fibres is not apparent in local diameter spectra near the optic nerve head. Integration of a ganglion cell density map of the retina from another rabbit indicates a total ganglion cell count lying between 455,000 and 547,000. The optic nerve fibre and ganglion cell counts are both substantially greater than the maximum fibre count previously repo

ISSN:0092-7317    

DOI:10.1002/cne.901700208

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractThe morphological 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), possesses an arborization most of which lies contralateral to its soma within the metathoracic ganglion. Midline surgical lesions in the metathoracic ganglion separated CDLM into a distal segment composed of the axon and most of the arborization, and a proximal segment comprised of the remaining arborization, neurite, and soma. Isolated axonal segments were produced by cutting the nerve root containing the axon of CDLM close to the ganglion.The normal anatomy of CDLM was determined by axonal dye‐fills using cobaltous chloride. Morphological changes in the isolated arborization of CDLM were examined by axonal dye‐fills at successive time intervals. Changes in the isolated CDLM axon were examined via dissection and histological cross‐sections of the distal nerve at graded time intervals.In one example, a remnant of the isolated CDLM arborization survived to 168 days postoperative, a time comparable to the longest previously‐reported physiological and morphological survival times of distalaxonalsegments of invertebrates. In general the isolated arborization does not survive this long. Normally occurring branches of the arborization can be preserved about 0 to 50 days. After this period branches of the arborization seem to be lost in progressive fashion from smaller to larger, leading to complete loss of the arborization and axon in most cases at 100 or more postoperative days. There is evidence for the presence of supernumerary fibers in the isolated CDLM arborization between 0 to 63 days postoperative. Such supernumerary fibers indicate an independent capacity for outgrowth of the isolated arborizationwithoutconnection to the nucleus.The distal axonal segment of CDLM degenerates physiologically and morphologically within 4 to 15 days after peripheral nerve section. This time course is close to that of Wallerian degeneration of vertebrate peripheral nerv

ISSN:0092-7317    

DOI:10.1002/cne.901700209

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

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 inTeleogrylluseventually 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 periph

ISSN:0092-7317    

DOI:10.1002/cne.901700210

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901700201

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY