Objective
To investigate the optimal condition for activation of motor cortex by electrical stimulation of forelimb in rat.

Method
Eleven adult rats (Sprague-Dawley rat) were studied, each of which was anesthetized and craniotomized. While the electrical stinulation was given on the contralateral forelimb of the fixed rat at stereotaxic frame, the evoked potential (EP) was obtained at the motor cortex of rat brain. The conditions of electrical stimulation were changed with 5 kinds of frequencies (1, 3, 5, 10, 15 Hz), 4 kinds of stimulus intensities (1, 3, 5, 7 mA) and 3 kinds of pulse widths (100, 200, 300μsec).

Results
The peak latencies of EPs in the motor cortex were significantly decreased and the amplitudes were significantly increased along with the decrement of stimulus frequency and the increment of stimulus intensity. The peak latencies and amplitudes of EPs were not significantly changed by stimulus pulse widths.

Conclusion
The motor cortex of rat was more activated with lower frequency and higher intensity regardless of pulse width in the given condition of electrical stimulation in this study. Key_words: 전기적 자극, 운동 피질, 유발전위, Electrical stimulation, Motor cortex, Evoked potential