Neurons of visual cortex respond to visceral stimulation during slow wave sleep.

It is hypothesized here that the same cortical areas which process signals from exteroreceptors (visual, acoustic, etc.) in wakefulness process signals from visceral organs during sleep. To check this hypothesis, the activity of 49 neurons (hypercomplex, complex and simple, as defined by conventional visual stimulation) was recorded from visual areas V1 and V2 in chronic cats at different stages of the sleep-waking cycle. Neuronal responses to electrical stimulation of the area of stomach and small intestine (single pulses of 100-500 microA. 0.5 ms duration) were investigated. It was found that intraperitoneal stimulation delivered during slow wave sleep evoked clear excitatory responses in most simple and complex cells. In hypercomplex cells, only inhibitory responses were observed. All these responses disappeared in wakefulness. These observations are compatible with the above hypothesis.