Interhemispheric reciprocal interaction between ventroposterolateral thalamic nuclei involving cortical relay neurons.

Extracellular and intracellular recordings were performed in the somatosensory cortex of cats anesthetized with sodium pentobarbital. Commissural neurons identified antidromically from the corpus callosum (CC) were activated synaptically at latencies compatible with a monosynaptic delay following stimulation of the thalamic ventroposterolateral (VPL) nucleus. Corticothalamic cells identified antidromically from the VPL nucleus were synaptically driven at latencies compatible with either a mono- or disynaptic delay following CC stimulation. We propose that an interhemispheric reciprocal interaction exists between VPL nuclei via cortical relay cells involving commissural and corticothalamic neurons.