Cardiovascular responses to rewarding brain stimulation.

In awake rats, rewarding stimulation of 155 electrodes spread throughout the forebrain, hypothalamus, and midbrain led to heart rate (HR) deceleration at almost all sites. Stimulation of those animals with forebrain electrodes that were fitted with a carotid catheter produced mean arterial pressure increases acompanying the HR changes. The relative latencies of the cardiovascular responses suggested that rewarding stimulation, in some instances at least, may produce a mixture of autonomic effects that rarely if ever occur in the normal waking animal in the absence of such stimulation. The data obtained when the rats with forebrain electrodes were anesthetized indicated that stimulation caused mean arterial pressure to fall and HR either not to change or to decelerate slightly. These differences between data from the same animals under waking and anesthetized conditions caution against premature generalizations concerning the effects of brain stimulation on cardiovascular changes.