Corticocortical fiber connections in the cat cerebrum: the frontal region.

TLDR: The Nauta silver degeneration technique was used to study the interconnections of the frontal cortex of the cat and the sensorimotor area is found to be highly organized through intrinsic short association fibers.

Abstract: The Nauta silver degeneration technique was used to study the interconnections of the frontal cortex of the cat. The sensorimotor area is found to be highly organized through intrinsic short association fibers. However, less specific connections are-revealed with other areas; for example, no direct fibers are recognized as passing from the sensorimotor cortex to the visual area. In the sensorimotor area, the association fibers from the first (SI) to the second somatic sensory area (SII) are generally denser than those passing in the reverse direction, particularly in regard to the leg subdivisions. Such a difference in density is less striking in regard to the arm subdivisions and much less in the face subdivisions. Long association fibers arise only from the first face area to the middle suprasylvian sulcus, a connection which may correspond to the superior longitudinal fasciculus in man. The number of callosal fibers connecting the homotopical regions between both hemispheres differs for each portion of the cortex. Callosal interconnections are doubtful for the gyrus proreus and the medial portion of both the anterior and posterior sigmoid gyri, While they appear sparse in the lateral portion of the latter gyri. Dense interconnections, by contrast, are seen in the coronal and anterior ectosylvian gyri. The degenerating fibers seen in layers V and VI mainly appear to represent fibers of passage, and those in layers III and IV seem to be Preterminal fibers.