摘要:

AbstractLocust flight is an exclusively adult behavior whose neural basis has been extensively studied. The coordinated neural pattern underlying this behavior appears rapidly at the end of postembryonic development. This paper examines the ontogeny of elements of the nervous system involved in the behavior. Alternative extreme hypotheses are: (1) the neurons and synapses involved develop concomitant with the behavior, or (2) they are constructed early in development, and are activated at the appropriate time by, for example, the release of inhibition. These hypotheses were evaluated by selecting a synapse that is important in adult flight, and monitoring its physiological features during postembryonic development.The synapse between the forewing Stretch Receptor (SR) and the First Basalar (BA) motor neuron, two uniquely identified neurons, mediates a monosynaptic reflex which operates only in flight. The EPSP, initiated by SR in BA, was recorded intracellularly during the last four of six postembryonic instars. As early as third instar, the monosynaptic EPSP is present and appears to be as effective as in the adult. It also decrements and summates similarly in younger animals and adults. Therefore, some flight system synapses are present and effective throughout most of postembryonic development, and thus do not develop concomitant with the behavior.

ISSN:0092-7317    

DOI:10.1002/cne.901910202

出版商:Alan R. Liss, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractAs part of an experimental study of the ventral striatum, the horseradish peroxidase (HRP) method was used to examine the afferent and efferent neuronal connections of the nucleus accumbens. Following iontophoretic applications or hydraulic injections of HRP in nucleus accumbens, cells labeled by retrograde transport of HRP were observed in the ipsilateral telencephalon in the posterior agranular insular, perirhinal, entorhinal, and primary olfactory cortices, in the subiculum and hippocampal field CA1, and in the anterior and posterior divisions of the basolateral amygdaloid nucleus. In the diencephalon, labeled neurons were present ipsilaterally in the central medial, paracentral and parafascicular intralaminar nuclei, and in the midline nuclei parataenialis, paraventricularis, and reuniens. Retrograde labeling was observed in the ipsilateral brainstem in cells of the ventral tegmental area and dorsal raphe. Many of these projections to nucleus accumbens were found to be topographically organized.Anterograde transport of HRP from nucleus accumbens demonstrated ipsilateral terminal fields in the ventral pallidum and substantia nigra, pars reticulata.The afferent projections to nucleus accumbens from the posterior insular and perirhinal neocortices, intralaminar thalamus, and the dopamine‐containing ventral tegmental area are analogous to the connections of the caudatoputamen, as are the efferents from nucleus accumbens to the substantia nigra and ventral globus pallidus. These connections substantiate the classification of nucleus accumbens as a striatal structure and provide support for the recently proposed concept of the ventral striatum. Furthermore, the demonstration that a number of limbic system structures, including the amygdala, hippocampal formation, entorhinal cortex, and olfactory cortex are important sources of afferents to the nucleus accumbens, suggests that the ventral striatum may serve to integrate limbic information into the striatal syste

ISSN:0092-7317    

DOI:10.1002/cne.901910203

出版商:Alan R. Liss, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractAs part of an experimental study of the ventral striatum, the horseradish peroxidase (HRP) method was used to examine the afferent and efferent neuronal connections of the olfactory tubercle. Following iontophoretic applications or hydraulic injections of HRP in the tubercle, neurons labeled by retrograde transport of HRP were observed ipsilaterally in the telencephalon in the main olfactory bulb, the medial, lateral, ventral, and posterior divisions of the anterior olfactory nucleus, and in the orbital, ventral, and posterior agranular insular, primary olfactory, perirhinal, and entorhinal cortices. Labeled cells were also present in the basolateral, basomedial, anterior cortical, and posterolateral cortical amygdaloid nuclei, and bilaterally in the nucleus of the lateral olfactory tract. In the diencephalon, ipsilateral HRP‐containing neurons were observed in the midline nuclei paraventricularis, parataenialis, and reuniens, and in the parafascicular intralaminar nucleus. Retrograde labeling was present in the ipsilateral brainstem in cells of the ventral tegmental area, substantia nigra, and dorsal raphe. Many of the above projections to the tubercle were found to be topographically organized.Anterograde axonal transport of HRP from the olfactory tubercle labeled terminal fields ipsilaterally in all parts of the anterior olfactory nucleus, in the ventral pallidum, and in the substantia nigra, pars reticulata. Contralaterally, terminal fields were present in the dorsal and lateral divisions of the anterior olfactory nucleus.The projections to the tubercle from the orbital, ventral, and posterior agranular insular, and perirhinal neocortices, intralaminar thalamus, and dopamine‐containing areas of the ventral mesencephalon are analogous to the connections of the caudatoputamen, as are the efferents from the tubercle to the ventral globus pallidus and substantia nigra. These connections substantiate the recent suggestion that the olfactory tubercle is a striatal structure, and provide support for the ventral striatal concept.In the present study of the olfactory tubercle, and in the first study in this series on the nucleus accumbens, the ventral striatum was found to receive projections from a number of limbic system structures, including the main olfactory bulb, anterior olfactory nucleus, amygdala, hippocampus, and subiculum, and the entorhinal and primary olfactory cortices. These findings suggest that the ventral striatum is concerned with integrating limbic information into the striatal sys

ISSN:0092-7317    

DOI:10.1002/cne.901910204

出版商:Alan R. Liss, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractImmunoreactive LHRH‐like material has been found in the cells and fibers of the nervus terminalis in fetal and adult guinea pig brains. LHRH‐containing neurons and axons are seen in the nasal mucosa intermingled with fibers of the olfactory nerves, in ganglia along the ventromedial surfaces of the olfactory bulbs and forebrain, and in clusters surrounding perforating branches of the anterior cerebral artery in the regions of the septal nuclei and olfactory tubercle. Nonreactive neurons are found adjacent to the LHRH‐positive cells in all of the ganglia. LHRH‐immunoreactive cells and axons of the nervus terminalis are in intimate contact with cerebral blood vessels and the cerebrospinal fluid along the intracranial course of this nerve, deep to the meninges. The possible involvement of these structures in the neural mechanisms of sexual behavior and the neurohormonal regulation of reproductive function are di

ISSN:0092-7317    

DOI:10.1002/cne.901910205

出版商:Alan R. Liss, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractBy means of a histofluorescence technique (FGS method), a postnatal ontogeny of dopaminergic neurons (DA‐cells) in the retina was studied in rats which had been born and reared under diurnal lighting (LD), reversed lighting (DL), constant lighting (LL), or continuous dark conditions (DD). The time of first appearance of DA‐cells was not altered by any of the above conditions; weakly fluorescent cell bodies were visible at about the 10th postnatal day. After the eyes were open the DA fluorescence of the cell body was gradually increased in intensity in all LD, DL, and LL rats, but not for DD rats. At the 16–17th day the processes of the cell first became visible, extending laterally to the inner plexiform layer. The somata and their processes appeared to be well developed at the postnatal 4–6th week, and they resembled those of the adult rat. On the other hand, the DA‐cells in the DD rats showed a weak fluorescence in both the somata and their processes. When the DD rats were transferred and reared under LD conditions for 1–3 days, the DA fluorescence was increased. These results strongly suggest that the initiation of retinal DA synthesis is independent of environmental lighting condition, but an adequate light stimulus is required for continued normal development of DA‐cells. Unlike in the rat, fluorescent cells in the guinea pig and chick retinas were observed to be fairly mature at birth or hatching. The developmental pattern of DA‐cells in the three species examined coincides with the maturation of

ISSN:0092-7317    

DOI:10.1002/cne.901910206

出版商:Alan R. Liss, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractIn order to gather information about the factors influencing myelination and neuroglial cell formation in the central nervous system, the development of myelin and neuroglia was investigated along the length of the optic nerve and tract of rats and rabbits. The results of this study revealed complex developmental patterns for both of these processes. Furthermore, the pattern of myelination for the rat is different from that of the rabbit. Myelination of the rat optic pathway exhibits a general rostro‐caudal gradient extending from the eye to the lateral geniculate nucleus, whereas a more homogeneous pattern is present in the rabbit. Myelination along the nerves of both species shows many sharp peaks and trough, especially in the region of the optic canal. Formation of myelin begins at several different sites along the nerve, with the first fibers appearing on both sides of the optic canal. Another small site of myelination develops just in front of the optic chiasm. Myelination of the entire length of an individual axon is not homogeneous but instead it begins at several discrete sites. The number of glial cells along the nerve and tract also fluctuates sharply but their pattern does not precisely parallel that of myelination. A better correlation is obtained by comparing the distribution of axons being myelinated with that of oligodendroglial cells. The complex patterns and the species differences observed in this study indicate that myelination and neuroglial cell development must be regulated by both neuronal and local factors. The data presented here together with other available information suggest that the vascularization of the nerve and the direct effects of hormones upon glial cells are possible factors that contribute to the local variabilit

ISSN:0092-7317    

DOI:10.1002/cne.901910207

出版商:Alan R. Liss, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractA procedure is described for constructing two‐dimensional, unfolded representations of the cerebral cortex. The technique is based on information contained in outlines of histological sections, and it allows an entire hemisphere to be represented on a single cortical map. Maps for different hemispheres from individuals of the same species are similar in size, shape, and organization, and their configuration is largely independent of the plane of sectioning used for reconstruction. Many types of information pertaining to the location and organization of different functional subdivisions can be displayed on cortical maps; representative applications of the technique to mapping cerebral cortex in the macaque and the cat are shown. Areal measurements on cortical maps correspond closely (generally within 20%) to actual surface areas in the intact hemisphere. Therefore, the maps can also be used to provide accurate determinations of the absolute and relative extent of various anatomical and functional subdivisions of the corte

ISSN:0092-7317    

DOI:10.1002/cne.901910208

出版商:Alan R. Liss, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractUndernutrition has been shown to have a profound effect on the central nervous system of maturing experimental animals, not only on gross brain weight and chemical constitution but also on cell structure and function. The present study was undertaken to determine the effect of protein malnutrition on the cortical barrels of mouse. Animals were conceived in and suckled by mothers maintained on an 8% casein diet or on a stock diet. After weaning, mouselings were maintained on their respective diets ad libitum. Four experiments were performed on these mouselings: (1) study of the development of the barrels by the Nissl method; (2) study of the effect of vibrissal damage at different postnatal ages; (3) study of the size of the barrel area and the number of neurons at different postnatal ages; and (4) study of the selectivity of the Golgi‐Cox method.The findings from comparison of malnourished mice with mice on a normal diet were: (1) a two‐day delay in the development of the barrels; (2) a two‐day lengthening of the period of vulnerability of barrel field neurons to neonatal vibrissal damage; (3) the barrel field area and the relative number of neurons were reduced, with the percentage of reduction decreasing with age; and (4) there was no significant difference in the average percentage of Golgi‐stained neurons at different ages.These results suggest that poor nutrition has a profound effect on the development and final form of a well‐defined neocortical region. The data presented here provide a useful base line against which various therapeutic regimens to reverse the effects of malnutrition on brain structure may be tested. They also suggest that inducing malnutrition may be an important way in which to manipulate the development of the nervous system in order to study the mechanisms responsible for its final form and

ISSN:0092-7317    

DOI:10.1002/cne.901910209

出版商:Alan R. Liss, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractFollowing single tectal lobe removal in the adult goldfish,Carassius auratus, the pattern of regeneration of the optic fibers which had previously projected to that tectum was examined at 1, 2, 4, 6, 8, 10, and 12 weeks postoperative using3H‐proline radioautography. We found that regenerating optic fibers grew across the midline through the transverse, minor, horizontal, and posterior commissures to innervate the remaining tectum. At early postoperative times innervation of the tectum was continuous, while later, the regenerating fibers segregated into discrete patches in the superficial layers of the tectum. In addition, regenerating fibers also grew into non‐optic centers/pathways such as the habenula, the fasciculus retroflexus, the forebrain, the torus semicircularis, the valvula and corpus cerebelli, the hypothalamus, and the medulla. While optic fibers were no longer apparent in the habenula and the fasciculus retroflexus after 2 weeks postoperative, all other structures were still occupied by the fibers at 12 weeks postoperative. Since most of the innervated pathways were either tectal efferent pathways, which should contain degenerating debris and proliferating glial cells after the tectal removal, or pathways closely associated with traumatized areas, we suggest that degenerating axonal debris and proliferating glia may play an important role in guiding regenerating fibers in this sys

ISSN:0092-7317    

DOI:10.1002/cne.901910210

出版商:Alan R. Liss, Inc.    

年代:1980

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901910211

出版商:Alan R. Liss, Inc.    

年代:1980

数据来源: WILEY