Study: NCT00715520

Intervention type: OTHER
Group type: EXPERIMENTAL
Intervention: Transcranial Magnetic Stimulation (TMS)
Description: Each TMS training session will begin with a baseline measurement lasting about 30 minutes in which brief magnetic pulses will be generated by the single-pulse and paired pulse TMS stimulator and the responses are recorded with surface EMG electrodes. Participants will be instructed to move their wrist for up to ½ hour. After these measures, rTMS will be applied to the scalp during training. Stimulation will occur at a low rate of different frequencies and different times with respect to the training movement depending on the experimental condition. In the last phase of the session post-training measurements will be done using single TMS pulses. TMS pulses and intensity with be given in random order.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Carbidopa-Levodopa
Description: Participants will receive one oral dose of carbidopa-levodopa 25mg one hour prior to measuring wrist extension movements.~The order in which Carbidopa-Levodopa is given will be randomized per participant.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Carbidopa-Levodopa
Description: Participants will receive one oral dose of carbidopa-levodopa 25mg one hour prior to measuring wrist extension movements.~The order in which Carbidopa-Levodopa is given will be randomized per participant.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Methylphenidate
Description: Participants will receive one oral dose of methylphenidate 40mg 2 hours prior to measuring wrist extension movements.~The order in which Methylphenidate is given will be randomized per participant.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Methylphenidate
Description: Participants will receive one oral dose of methylphenidate 40mg 2 hours prior to measuring wrist extension movements.~The order in which Methylphenidate is given will be randomized per participant.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Amphetamine Sulfate
Description: Participants will receive one oral dose of amphetamine sulfate 10mg 2 hours prior to measuring wrist extension movements.~The order in which Amphetamine Sulfate is given will be randomized per participant.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Amphetamine Sulfate
Description: Participants will receive one oral dose of amphetamine sulfate 10mg 2 hours prior to measuring wrist extension movements.~The order in which Amphetamine Sulfate is given will be randomized per participant.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Placebo
Description: Participants will receive one oral tablet of placebo 2 hours prior to measuring wrist extension movements.~The order in which Placebo is given will be randomized per participant.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Placebo
Description: Participants will receive one oral tablet of placebo 2 hours prior to measuring wrist extension movements.~The order in which Placebo is given will be randomized per participant.

Intervention type: OTHER
Group type: EXPERIMENTAL
Intervention: Sham Transcranial Magnetic Stimulation (TMS)
Description: Sham TMS pulses will be randomly administered during TMS sessions.

Intervention type: OTHER
Group type: EXPERIMENTAL
Intervention: Sham Transcranial Magnetic Stimulation (TMS)
Description: Sham TMS pulses will be randomly administered during TMS sessions.

Intervention type: OTHER
Group type: EXPERIMENTAL
Intervention: Transcranial Magnetic Stimulation (TMS) Training
Description: TMS surface electromyographic activity will be recorded with surface electrodes mounted on the skin overlaying a forearm muscle. Single pulses of TMS at increasing intensity will be delivered to measure motor cortex excitability. Peak acceleration and TMS evoked responses in the muscle will be measured prior to the training, after completion of the training and again one hour after completion of the training.

Intervention type: OTHER
Group type: EXPERIMENTAL
Intervention: Transcranial Magnetic Stimulation (TMS) Training
Description: TMS surface electromyographic activity will be recorded with surface electrodes mounted on the skin overlaying a forearm muscle. Single pulses of TMS at increasing intensity will be delivered to measure motor cortex excitability. Peak acceleration and TMS evoked responses in the muscle will be measured prior to the training, after completion of the training and again one hour after completion of the training.