Behavioural and cardiovascular responses to electrical stimulation of the medulla oblongata of the cat.

Effects of stimulation of the nucleus tractus solitarii, the dorsal motor nucleus of the vagus, the nucleus reticularis paramedianus, and the nucleus cuneatus were studied in free-moving cats. Stimulation of the medullary nuclei that are known to be involved in the central nervous control of cardiovascular functions might activate preprogrammed motor responses such as licking and sniffing, and induce complex behavioural response patterns such as sleep or flight reaction. Moreover, both lever-pressing for rewarding brain stimulation, and eating in food deprived cats might be modulated by these stimulations. In a shuttle box the cats showed no tendency toward shuttling during stimulation, except the stimulation of the nucleus reticularis paramedianus which produced aversion. The cardiovascular and respiratory effects varied parallel with the behavioural responses. It is concluded that the medullary nuclei related to visceral functions are capable of affecting somatomotor behaviour either directly on the motor system, or by inducing complex response patterns in which somatomotor and visceral responses are integrated.