This study will examine how the two sides of the brain interact when learning precision hand movements. Both sides of the brain are active when a person performs an accurate hand movement. This study will look at the extent to which the two brain hemispheres interact when learning accurate hand movements.
Healthy, right-handed normal volunteers 18 - 40 years of age may be eligible for this study. Candidates are screened with a clinical and neurological examination.
Participants are randomly assigned to one of two groups - precision or non-precision hand movements. All participants undergo the following procedures:
- Force precision task: Subjects are press a small device between the thumb and index finger. The force produced with the fingertips is translated onto a computer screen. Subjects track a white line passing on the screen with their fingertips.
- Paired-pulse transcranial magnetic stimulation (TMS): A wire coil is held to the subject's scalp. A brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the brain. During the stimulation, the subject may be asked to tense certain muscles slightly or perform other simple actions. The stimulation may cause a twitch in muscles of the face, arm, or leg, and the subject may hear a click and feel a pulling sensation on the skin under the coil. The effect of paired-pulse TMS on the muscles is detected with electrodes taped to the skin on the arms or legs.
- Surface electromyography (EMG): This test measures the electrical activity of muscles. For this test, electrodes are filled with a gel and taped to the skin over the muscle to be tested.
The study involves six sessions. Sessions 1-5 are on consecutive days; session 6 is one week after session 5.
- Session 1: Familiarization with the motor task and baseline measurements, including error rate, EMG, and paired-pulse TMS
- Session 2: Training in the motor task and repeat measurements as in session 1
- Session 3: Training and measurements as in session 2
- Session 4: Training and measurements as in session 2
- Session 5: Training and measurements as in session 2
- Session 6: Measurements only