Thalamic Projections to Parietal Cortex

Abstract

Thalamic projections to parietal regions of cerebral cortex were investigated in the cat by retrograde degeneration and retrograde transport techniques. Studies of retrograde cellular changes indicated cortically projecting cells in the lateroposterior nucleus (LP), rostral pulvinar (Pul) and the ventral part of the laterodorsal nucleus (LD). When lesions were placed in the cortex of young kittens, clear chromatolytic changes and cell loss were also consistently observed in middle and caudal parts of the ventroanterior nucleus (VA). Investigations of retrograde transport following intracortical injections of horseradish peroxidase confirmed the results of retrograde degeneration studies by demonstrating cortically projecting cells in VA, LP, LD and Pul. Retrograde transport studies also indicated cortically projecting cells in the central lateral nucleus. Material from both experimental techniques demonstrated a loose topographic organization of the projections from the lateral thalamus. Anterior parts of LP project to the anterior lateral gyrus and anterior middle suprasylvian gyrus. Middle LP and rostral Pul project to the middle suprasylvian gyrus.