Central control and interactions affecting sympathetic and parasympathetic activity.

Current thinking concerning the central control of the autonomic nervous system and the central interactions affecting sympathetic and parasympathetic activity is presented. Among the questions discussed are the following: are there neurons within the common brain stem system which exert an influence on preganglionic parasympathetic neurons and can they be differentiated from neurons which affect sympathetic preganglionic neuron functions? What interactions occur between sympathetic and parasympathetic tone-mediating neurons? In discussing these problems information is presented as obtained by recording from reticular formation (RF) neurons with discharge patterns similar to efferent parasympathetic activity. The general conclusion reached is that there is a common central control; interactions occur in the brain stem as well as peripherally; depending on the functional situation, these two systems can be organized to act either reciprocally or non-reciprocally.