Effects of stimulating the caudal zones of the mesencephalic reticular formation on the postcruciate cortex of the cat]

The influence of the electrical stimulation of the dorsolateral (DL) and the ventromedial (VM) portions of the caudal area of the mesencephalic reticular formation on the neuronal activity of the lateral zone of the gyrus sygmoideus posterior was investigated in cats. The mesencephalo-cortical influences were mainly excitatory in character; the predominance of the neuronal reactions with a short latency (3--12 msec) during the VM stimulation and reactions with a longer latency (20--25 msec) during the DL stimulation was revealed. The VM and the DL were found to influence both cortical neurones, the ones sensitive to somesthetic stimuli (mono-, di- and polyvalent) and the ones which failed to respond to the electrocutaneous stimulation of the limbs.