Asymmetric activation of motor cortex controlling human anterior digastric muscles during speech and target-directed jaw movements.

Like most of the cranial muscles involved in speech, the trigeminally innervated anterior digastric muscles are controlled by descending corticobulbar projections from the primary motor cortex (M1) of each hemisphere. We hypothesized that changes in corticobulbar M1 excitability during speech production would show a hemispheric asymmetry favoring the left side, which is the dominant hemisphere for language processing in most strongly right handed subjects. Fifteen volunteers aged 24.

Transcranial magnetic stimulation reduces masseter motoneuron pool excitability throughout the cortical silent period.

Objective: To evaluate the time-course of changes in masseter motoneuron pool excitability following transcranial magnetic stimulation of motor cortex, and relate this to the duration of the masseter cortical silent period (CSP).

Methods: Surface EMG was recorded bilaterally from masseter and digastric muscles in 13 subjects. Focal TMS was applied at 1.