Afferent information derived from proprioceptive and cutaneous mechanosensitive inputs may play an important role in the moment-to-moment coordination of movement. It is hypothesized that speech which involves small forces and movements, is strongly influences by such afferent information. At present, very little information is available concerning the effects of innocuous mechanical inputs on oromotor behaviors. The proposed studies will expand our knowledge of sensorimotor integration on force control in the perioral complex by using the mechanically evoked perioral reflex paradigm as a probe to quantify the changes in excitability occurring at the level of the facial nucleus during sucking, lip posturing, and speech. Experiments will involve testing subjects throughout the age range from infants to elderly adults. It is hoped that the proposed experiments will provide new developmental information on the relations between controlled mechanical inputs delivered to the lower face and features of evoked muscle activity, including specificity, modulation, and spatial summation. In addition, the testing of infants and very young children will provide new means to quantitatively assess trigemino-facial function in these populations.
