Degeneration of some intralaminar thalamic nuclei after cortical removals in the cat

The projections of the central medial, paracentral, and central lateral nuclei of the cat have been studied by the method of retrograde degeneration. Following removal of neocortex, with preservation of rhinencephalic and sub‐cortical structures, the central medial, paracentral, and central lateral nuclei degenerate severely. The central medial and paracentral nuclei degenerate only after extensive cortical lesions which include limbic cortex. There is evidence of a topographical organization of the projection since rostral sectors of central medial and paracentral nuclei show cell loss after lesions involving anterior limbic and orbitofrontal cortex while caudal sectors degenerate after lesions involving cingulate and parieto‐occipital cortex. The central lateral nucleus projects to cortex of the parieto‐occipital region. Some findings are considered which indicate that fibers from the central medial, paracentral, and central lateral nuclei travel rostrally to the region of the head of the caudate nucleus before turning caudally to distribute to cortical areas.