SEROTONIN AND MOTOR-ACTIVITY

The activity of brain serotonergic neurons in both the pontine-mesence phalic and medullary groups is positively correlated with the level of behavioral arousal and/or the behavioral state. This, in turn, appear s to be related to the level of tonic motor activity, especially as ma nifested in antigravity muscles and other muscle groups associated wit h gross motor activity. In addition, a subset of serotonergic neurons displays a further increase in activity in association with repetitive , central pattern generator mediated responses. Accumulating evidence indicates that this relation to motor activity is related both to the cc-activation of the sympathetic nervous system and to the modulation of afferent inputs.