The effect of peripheral stimulation on the electrical activity of the neocortex in chronic premesencephalic cats

: Chronic experiments were carried out with 19 adult cats. It is demonstrated that following a premesencephalic sectioning of the brain stem, with the lemniscal pathways being spared, on the second and third day after the surgery, auditory, olfactory and skin stimulations caused diffusive activation of the neocortex. Photic stimulation, though evoking responses in the visual cortex, was unable to desynchronize the neocortical electrical activity. Taking into account the data on the organization of hypothalamic afferent connections, it is suggested that diffuse activation of the neocortex in cats, when the mesencephalic reticular formation is completely excluded, occurs during auditory, olfactory and skin stimulations due to excitation of the posterior hypothalamus.