ネコ視床の内側下核と内側腹側核の皮質投射に関する実験解剖学的研究

Cortical projections of the submedial and medial ventral nuclei (the dorsal and ventral divisions of the medial ventral nucleus in a wide sense) were studied using the Nauta silver method. Localized stereotaxic lesions anywhere in these nuclei tend to cause scattered terminal degeneration in almost the whole extent of the frontal granular cortex, if the lesion is not so small. In addition, dense terminal degeneration occurs in certain region of the frontal cortex, which varies with the site of the lesion. Following lesions in the submedial nucleus, dense terminal degeneration is found largely in the medial and basal regions of the frontal cortex, while lesions in the medial ventral nucleus lead to dense degeneration mainly in the superolateral region of the frontal cortex (the prorean gyrus), including the lower bank of the presylvian sulcus. The boundary between the marked cortical projection areas of the submedial and the medial ventral nuclei may be represented by the anterior rhinal sulcus. Marked cortical projections of the submedial and medial ventral nuclei appear to be topographically organized also in an anteroposterior manner. In all the cases studied, degenerated terminals in the affected cortex were found in all layers, except for layer 2, where only fibers of passage were found. In layer 4 and the adjacent portion of layer 3, terminal degeneration was most dense. In the superficial portion of layer 1, a fair number of terminals were seen.