[The reactions of the respiratory neurons of the medulla oblongata to the burst stimulation of the hypothalamus].

The responses of inspiratory and expiratory neurons of the ventral respiratory nucleus to stimulation of postero-lateral hypothalamus at different phases of respiratory cycles, were studied in anesthetized cats. The stimulation in the first half of the inspiratory cycle evoked excitatory responses in 72% of inspiratory neurons and an inhibitory type of responses in 28%. The stimulation during the second half of the inspiratory phase did not change significantly the patterns of inspiration. The stimulation of the hypothalamus during expiratory phase depressed the activity of expiratory neurons and reversed the phases of the respiratory cycle. Recording of the unit activity of inspiratory neurons revealed an extra burst of spikes in response to stimulation of the hypothalamus in different moments of expiratory phase. Possible neuronal mechanisms of hypothalamic influence on switching off of the expiration and switching on of the inspiration, are discussed.