Corticothalamic connections of suprasylvian cortex in monkey

Cortical lesions were made along the superior border of the sylvian fissure in 11 squirrel and four macaque monkeys. The course of degenerating fibers in the thalamus was determined by utilizing the Nauta and Fink-Heimer I techniques. The principal projection sites of suprasylvian cortex were found to be the nuclei ventralis posterior medialis, ventralis posterior lateralis, ventralis posterior inferior, pulvinaris oralis, and pulvinaris medialis. Lesser amounts of terminal degeneration occurred in the nuclei reticularis, ventralis lateralis, lateralis posterior, the intralaminar nuclei, and the posterior and pretectal areas of the thalamus. The connections of the suprasylvian cortex that corresponds to somatosensory area II with a phylogenetically new thalamic nucleus, the pulvinaris oralis, suggests a specialization of SII functions in the monkey.