Comparative Analysis of the Quantitative Characteristics of the Corticothalamic Projections of Parietal Cortex Fields 5 and 7
The quantitative distributions of corticothalamic efferent fibers after local lesioning of fields 5 and 7 of the parietal cortex were studied. The largest projections of field 5 and 7 were found to be to the reticular and parafascicular nuclei of the thalamus and the zona incerta. The number of efferent fibers of field 5 terminating in these nuclei was greater than the number of fibers running from field 7. The projections of field 7 to the posterolateral nucleus were greater than those of field 5. The numbers of parietal cortex efferent fibers terminating in the central lateral and ventral anterior nuclei and thalamic pulvinar were insignificant. Thus, the predominant projections of fields 5 and 7 to the reticular and parafascicular nuclei of the thalamus and the zona incerta may be determined by the need for inhibitory control of descending corticoreticular influences.
Key wordsparietal cortex thalamus efferent connections
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