[Morphophysiologic study of the afferent projections of the posterolateral nucleus of the thalamus in the rat].

Afferent connections of the posterolateral nucleus of the thalamus were studied in rat using retrograde axonal transport of horseradish peroxidase. It was shown that the posterolateral nucleus receives ascending projections from SC, GL, PT, VP, VL, zona incerta and hypothalamus as well as descending projections from cortical areas 18A, 20, 18, 7, 29c , 17 and 36 and from fascia dentata of rippocampus as well. In electrophysiological experiments 134 from 229 investigated neurons of the posterolateral nucleus responded to isolated or simultaneous visual, auditory and cutaneous stimulations. 53 neurons were monosensory units; they responded only to visual (41/53) or cutaneous (12/53) stimulation. Cells responding only to auditory stimulation were not found. Polysensory neurons (81/134) showed convergence of signals from two-three sensory systems and received preferential inputs from visual and somatosensory systems. The polysensory cells showed nonlinear interaction between responses during heterosensory stimulations.