Electromyographic (EMG) studies of thelip and jaw muscles in individuals with IPDhave provided some evidence for increasedlevels of tonic resting and background activity as well as for loss of reciprocitybetween agonist and antagonistic musclegroups in these individuals.These findings are consistent with evidence for abnormalsensorimotor gating in the orofacial and limbsystems, which are presumably related to basalganglia dysfunction.Whether or not theseabnormal sensorimotor findings are indicativeof excess stiffness or rigidity in the speechmusculature is not clear.