Modulation of stimulus-induced 20-Hz activity for the tongue and hard palate during tongue movement in humans.

OBJECTIVE

Modulation of 20-Hz activity in the primary sensorimotor cortex (SM1) may be important for oral functions. Here, we show that 20-Hz event-related desynchronization/synchronization (20-Hz ERD/ERS) is modulated by sensory input and motor output in the oral region.

METHODS

Magnetic 20-Hz activity was recorded following right-sided tongue stimulation during rest (Rest) and self-paced repetitive tongue movement (Move). To exclude proprioception effects, 20-Hz activity induced by right-sided hard palate stimulation was also recorded. The 20-Hz activity in the two conditions was compared via temporal spectral evolution analyses.

RESULTS

20-Hz ERD/ERS was detected over bilateral temporoparietal areas in the Rest condition for both regions. Moreover, 20-Hz ERS was significantly suppressed in the Move condition for both regions.

CONCLUSIONS

Detection of 20-Hz ERD/ERS during the Rest condition for both regions suggests that the SM1 functional state may be modulated by oral stimulation, with or without proprioceptive effects. Moreover, the suppression of 20-Hz ERS for the hard palate during the Move condition suggests that the stimulation-induced functional state of SM1 may have been modulated by the movement, even though the movement and stimulation areas were different.

SIGNIFICANCE: Sensorimotor function of the general oral region may be finely coordinated through 20-Hz cortical oscillation.