摘要:

We defined spatial patterns of organization of projections from somatosensory cerebral cortex (SI) to the somatosensory cerebellar cortex of anesthetized albino rats using microelectrode (stimulation and recording) micromapping methods and low-threshold cutaneous (tactile) stimulation. Two sampling strategies were used: (1) a single cerebral SI locus in layers V-VI was stimulated electrically, while a responding region of the cerebellar granule cell (GC) layer was systematically mapped with a recording electrode; (2) the SI stimulating electrode was used as the mapping electrode while the cerebellar GC eletrode remained fixed. We found highly specific patterns of connections between somatotopically organized SI cortex and the somatotopically fractured tactile cerebellar cortex. Using threshold stimulating currents in SI, the projections from small populations of neural elements were found to be highly restricted, terminating within the confines of only those tactile cerebellar hemispheric locations having the same receptive fields (RFs). These SI-GC projections conform to the patchy mosaic pattern of organization previously shown for peripheral tactile projections. SI projections to GC patches were either contralateral or ipsilateral, depending on the laterality of the peripheral projections to that patch. Each SI focus projected to only a portion of a patch; projections from several adjacent SI loci overlapped serially within a patch. As with the peripherally evoked GC layer responses, SI-evoked GC responses were organized in a columnar fashion and were maximal at middle levels of the GC layer; SI-GC latencies were 5–8 ms. These data reveal that this tactile-related cerebro-cerebellar circuit exhibits precisely organized patterns of projectio

ISSN:0006-8977    

DOI:10.1159/000121772

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Optic fiber projection in the brain of Salamandra salamandra was investigated by degeneration techniques. Terminal fields are described in the thalamus and in the optic tectum. Microelectrode recordings were performed from ganglion cells in the retina and from their terminals in the thalamus and tectum in Salamandra and Triturus alpestris. ''On'' cells showed maximal sensitivity either in the blue or in the yellow spectral region; they project to the thalamus. Color coding ''on-off cells project to the tectum opticum. In Triturus a seasonal change in these neurons occurs. Probably due to transition of vitamin A2 into vitamin A1 the spectral sensitivity is different. In springtime blue-red opponent-color neurons were recorded, in fall however, blue-yellow neurons were found.

ISSN:0006-8977    

DOI:10.1159/000121773

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Eccles cites three items of physiological evidence for a self-conscious mind: experiments by Libet, showing that consciousness can antedate sensory experience; slow build-up of the readiness potential, showing that the mind is weak; that brain events are scattered, but consciousness is a unity. I argue that none of the three items has any significance: the first is a confusion about the experimental evidence; the second indicates weak physical forces, not mind; the third replaces visible structures by intangible influences. Thus, these physiological arguments do not support the contention that non-physical influences are at work.

ISSN:0006-8977    

DOI:10.1159/000121774

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Projections from visual thalamus to posterior cortex of the Virginia opossum revealed by retrograde transport of horseradish peroxidase show a specific and orderly pattern. The lateral geniculate nucleus projects only to cortical area 17, while a lateral sector of the lateral posterior nucleus sends afferents both to areas 17 and 18. Area 19 receives input from the lateral intermediate nucleus; the caudomedial sector of the lateral posterior nucleus projects to the anterior and posterolateral areas of cortex. These features are generalized to other mammals to include thalamic input differentially derived from retinal, tectal, pretectal and cortical sources.

ISSN:0006-8977    

DOI:10.1159/000121775

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The size and composition of the brains of the quokka wallaby (Setonix brachyurus) and the brush-tailed possum (Trichosurus vulpecula) were compared with those of the rat, rabbit, cat, sheep, and human. Separate structures were taken from the brains by standardized dissection and their weights compared. Particular attention was paid to the relationships between the size of the amygdala and other brain structures.Marsupials were within the eutherian range in the ratio of whole brain weight to body weight. They were also within eutherian ranges in the proportion of the total brain weight formed by all structures, except the striatum, and in the proportion of the non-neocortical brain weight contributed by all structures but the olfactory bulbs. In all measures the marsupials were within the general range for eutherian mammals reported in the literature. The size of the amygdala was related significantly to that of the septum, hypothalamus, thalamus, lower brain stem, and olfactory bulbs.

ISSN:0006-8977    

DOI:10.1159/000121776

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The fissure patterns of 112 cat brains were examined and 45% were found to be asymmetric with respect to Otsuka and Hassler sulcus pattern types. As well, 22% were asymmetric with respect to the presence of a postcrutiate sulcus. No relationship was found between the presence or asymmetry of specific cortical features and paw preference, suggesting that these asymmetries are not associated with a functional asymmetry in visual discrimination performance previously demonstrated in the cat.

ISSN:0006-8977    

DOI:10.1159/000121777

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The cortical projection area of the thalamic mediodorsal nucleus (MD) was investigated using the horseradish peroxidase technique. Distinct relations between subdivisions of MD and of the prefrontal cortex were established: the medial sector of MD projects to sulcal cortex dorsal to the rhinal fissure and to the lateral frontopolar region; the lateral sector of MD reaches mainly cortex within the medial part of the hemisphere from the frontopolar region up to a mid corpus callosal level. The projection area of the lateral sector of MD overlaps with the projection fields of the paratenial and anteromedial nuclei. It is concluded that the guinea pig''s prefrontal cortex, defined as the projection area of MD, has strong similarities with the prefrontal cortices of rats and rabbits, that is with the prefrontal cortices of species of two different orders.

ISSN:0006-8977    

DOI:10.1159/000121778

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The sulcal or medial subdivision of the prefrontal cortex of the guinea pig was ablated after the animals had learned a spatial delayed-alternation task. Retention of this task was significantly impaired only after ablation of the medial prefrontal cortex. As the most critical cortical region for delayed-alternation performance in the rat is also situated in the medial prefrontal cortex, our findings suggest a close functional correspondence of the prefrontal cortices of these rodent species.

ISSN:0006-8977    

DOI:10.1159/000121779

出版商:S. Karger AG    

年代:1981

数据来源: Karger