摘要:

The evoked potential method was used to define the cortical visual, auditory and somatosensory areas in the mouse. Two somatotopic representations (SmI and SmII) were found which in general conform to the patterns described for other placental mammals. The representation of the face, and particularly the mys-tacial vibrissae, was greatly expanded in SmI. Nissl stained sections through the SmI face area revealed an unusual organization of the granule cells in layer IV. By correlating the appearance of layer IV as seen in sections perpendicular and parallel to the plane of layer IV, it was shown that the granule cells form cylindrical multicellular cytoarchitectonic units which, because of their shape, were called ''barrels''.The barrels were used as markers to define a cytoarchitectonic field – the barrel field – which was found to coincide with the SmI representation of the face and parts of the forepaw. Within the barrel field, a particularly consistent region was recognized – posteromedial barrel subfield (PMBSF) – in which the organization of the barrels was remarkably similar to the organization of tactile organs – the vibrissae on the contralateral face. Each PMBSF barrel is directly related to a single vibrissae since neonatal lesions of the vibrissae resulted in a predicted altered pattern in the PMBSF. And, some species which have more rows of whiskers than the mouse have more rows of PMBSF barrels.The larger PMBSF barrels contained approximately 2,000 neurons and the cytoarchitectonic basis for the barrels was shown to be purely a neuronal packing phenomenon. There was a direct proportionality between the number of myelinated fibers supplying a vibrissa and the number of neurons in the barrel to which it projects. In Golgi preparations, 85% of the layer IV neurons were found to have their dendritic processes restricted to a single barrel. From quantitative measures, Golgi impregnated barrel neurons were found to belong to only two fundamental classes: the Class I cells had smaller somata and spiny dendrites, while the Class II cells had larger somata and smooth dendrites. The specific thalamocortical projections from the ventrobasal complex to the barrels were demonstrated to terminate only within individual barrels. Silver grain counts of these projections showed that the terminal distribution within a barrel is not homogeneous.The cytoarchitectonic alterations in the PMBSF which were produced by vibrissal damage in young animals corresponded directly to an altered organization in the thalamocortical projections. There was a ''critical period'' after which it was not possible to alter PMBSF architecture, but during which there was a progressive pattern of cortical changes. Following the peripheral lesions, there was no loss of total PMBSF area, but rather barrels adjacent to the affected zone became enlarged as if to ''compensate'' for areal losses produced by the lesions.From experiments using the metabolic marker 2-deoxyglucose, it was shown that the barrels were part of a cortical columnar organization extending from pia to white matter. In addition, these experiments showed that removal of the vibrissal hairs alone was sufficient to deprive the barrel cortex of activity in behaving animals.These results are discussed in relation to some of the developmental determinants of cortical structure and possible mechanisms for the evolution of organization in established sensory

ISSN:0006-8977    

DOI:10.1159/000123786

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The evoked potential method was used to define the cortical visual, auditory and somatosensory areas in the mouse. Two somatotopic representations (SmI and SmII) were found which in general conform to the patterns described for other placental mammals. The representation of the face, and particularly the mys-tacial vibrissae, was greatly expanded in SmI. Nissl stained sections through the SmI face area revealed an unusual organization of the granule cells in layer IV. By correlating the appearance of layer IV as seen in sections perpendicular and parallel to the plane of layer IV, it was shown that the granule cells form cylindrical multicellular cytoarchitectonic units which, because of their shape, were called ''barrels''.The barrels were used as markers to define a cytoarchitectonic field – the barrel field – which was found to coincide with the SmI representation of the face and parts of the forepaw. Within the barrel field, a particularly consistent region was recognized – posteromedial barrel subfield (PMBSF) – in which the organization of the barrels was remarkably similar to the organization of tactile organs – the vibrissae on the contralateral face. Each PMBSF barrel is directly related to a single vibrissae since neonatal lesions of the vibrissae resulted in a predicted altered pattern in the PMBSF. And, some species which have more rows of whiskers than the mouse have more rows of PMBSF barrels.The larger PMBSF barrels contained approximately 2,000 neurons and the cytoarchitectonic basis for the barrels was shown to be purely a neuronal packing phenomenon. There was a direct proportionality between the number of myelinated fibers supplying a vibrissa and the number of neurons in the barrel to which it projects. In Golgi preparations, 85% of the layer IV neurons were found to have their dendritic processes restricted to a single barrel. From quantitative measures, Golgi impregnated barrel neurons were found to belong to only two fundamental classes: the Class I cells had smaller somata and spiny dendrites, while the Class II cells had larger somata and smooth dendrites. The specific thalamocortical projections from the ventrobasal complex to the barrels were demonstrated to terminate only within individual barrels. Silver grain counts of these projections showed that the terminal distribution within a barrel is not homogeneous.The cytoarchitectonic alterations in the PMBSF which were produced by vibrissal damage in young animals corresponded directly to an altered organization in the thalamocortical projections. There was a ''critical period'' after which it was not possible to alter PMBSF architecture, but during which there was a progressive pattern of cortical changes. Following the peripheral lesions, there was no loss of total PMBSF area, but rather barrels adjacent to the affected zone became enlarged as if to ''compensate'' for areal losses produced by the lesions.From experiments using the metabolic marker 2-deoxyglucose, it was shown that the barrels were part of a cortical columnar organization extending from pia to white matter. In addition, these experiments showed that removal of the vibrissal hairs alone was sufficient to deprive the barrel cortex of activity in behaving animals.These results are discussed in relation to some of the developmental determinants of cortical structure and possible mechanisms for the evolution of organization in established sensory

ISSN:0006-8977    

DOI:10.1159/000123787

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

In this investigation, the projections of the dorsomedial (viz. hippocampus) and adjacent dorsolateral cortical mantle (viz. parahippocampus) of the pigeon telencephalon were studied with the use of 3H-amino acid radioautography. The results indicate that the fibers which arise from these cortical areas project to the septum. The projection to this structure is topographically organized in a crude manner along the longitudinal axis of the hippocampal complex. Fibers arising from rostral levels of the dorsomedial hippocampal complex project principally to central portions of the precommissural septum, and to the nucleus of the diagonal band. Cells situated in the rostral parahippocampal area project to the entire region of the commissural and precommissural septum. Fibers arising from the caudal aspect of the dorsomedial cortical mantle project ipsilaterally to the dorsolateral septum and bilaterally to central portions of the postcommissural septum. However, fibers arising from more lateral parts of cortex terminate ipsilaterally along the entire longitudinal extent of the septum. Other classical projections of the hippocampal formation in the mammal which innervate the hypothalamus and thalamus could not be identified in the present study. Thus, it appears that the projections arising from both the hippocampal formation and adjacent lateral cortices of the pigeon correspond entirely to the precommissural fornix of the mammal.

ISSN:0006-8977    

DOI:10.1159/000123788

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The efferent connections of the septum in the pigeon were studied with the use of anterograde (3H-leucine autoradiography) and retrograde (horseradish peroxidase histochemistry) transport methods. It was observed that the dorsal septum projects to the lateral hypothalamus, portions of the periventricular hypothalamus, dorsomedial thalamus and midbrain reticular formation. Fibers from the ventral half of the septum (i.e., nucleus of the diagonal band) project to medial and lateral sectors of the hypothalamus, dorsomedial thalamus, lateral habenular nucleus and midbrain tegmentum. In addition, fibers originating from this region also project to the hippocampal and parahippocampal cortices.

ISSN:0006-8977    

DOI:10.1159/000123789

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

A reexamination of wavelength discrimination using a 2-choice paradigm and both chromatic-chromatic and chromatic-achromatic stimulus pairs has reaffirmed the positive tendency of Rana pipiens to approach short wavelengths. In addition, a strong avoidance of long wavelengths was observed and an interaction of these two opposite response tendencies was demonstrated. Thus, the percent choice frequency for a short-wavelength stimulus depends upon the stimulus with which it is paired. A positive phototaxis appears to influence response to some short-wavelength stimuli when they differ in brightness from an achromatic stimulus, but not with wavelengths above 471 nm.

ISSN:0006-8977    

DOI:10.1159/000123790

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The brush-tailed possum, Trichosurus vulpecula, displays an unusual amount of phenotypic variation within its central nervous system. These variations are expressed in terms of gross brain morphology, as evidenced by the occurrence of both highly lissencephalic and gyrencephalic neocortices in apparently normal adult animals; by displacement and asymmetry of certain internal structures, notably within the ventral thalamic nuclei; and by the inconstant occurrence of at least one cell group within the thalamus. These variations are described and discussed with reference to possible functional, ontogenetic and phylogenetic significance.

ISSN:0006-8977    

DOI:10.1159/000123791

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The brush-tailed possum, Trichosurus vulpecula, displays an unusual amount of phenotypic variation within its central nervous system. These variations are expressed in terms of gross brain morphology, as evidenced by the occurrence of both highly lissencephalic and gyrencephalic neocortices in apparently normal adult animals; by displacement and asymmetry of certain internal structures, notably within the ventral thalamic nuclei; and by the inconstant occurrence of at least one cell group within the thalamus. These variations are described and discussed with reference to possible functional, ontogenetic and phylogenetic significance.

ISSN:0006-8977    

DOI:10.1159/000123792

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Western collared lizards, Crotaphytus collaris, were tested in three experiments using electrical stimulation of the brain. In experiment 1, agonistic behavior (defensive, aggressive and escape) responses were elicited in free-moving unanesthetized lizards. In experiment 2, areas were localized from which gular extension, a common component of defensive and aggressive behavior, could be evoked in anesthetized animals. Experiment 3 was carried out to demonstrate that defensive and aggressive behavior could be elicited from the same stimulation sites both in anesthetized and unanesthetized lizards. Initially, gular extension was evoked while the animal was anesthetized and later the animal was tested while freely moving and unanesthetized. Based on a combined plot of the sites from which defensive and aggressive behavior was evoked in experiments 1–3, the higher threshold sites (51–750 µA) were in the dorsal ventricular ridge anterior, amygdaloid complex, septal and preoptic areas, hypothalamus, thalamus and adjacent to the nucleus profundus mesencephali (NPM) and reticular formation. Lower threshold sites (up to 50 µA) are found in the NPM and the reticular formation. Escape behavior can be evoked from stimulation sites within or adjacent to areas from which defensive and aggressive behavior can be eli

ISSN:0006-8977    

DOI:10.1159/000123793

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:0006-8977    

DOI:10.1159/000123794

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:0006-8977    

DOI:10.1159/000123795

出版商:S. Karger AG    

年代:1978

数据来源: Karger