Study: NCT01019343

Intervention type: PROCEDURE
Group type: ACTIVE_COMPARATOR
Intervention: MRI techniques
Description: MRI sub-studies will be conducted on 3.0 T or 7T units in the NMR Research Center. All volunteers will comply with the yearly requirement of a standard clinical diagnostic MRI scan of the head performed at 3.0T, to be submitted to the Diagnostic Radiology Department of the Clinical Center for interpretation. If the subject does not have a clinical scan performed within 12 month of the exam, a standard clinical MRI will be performed and reviewed before the research MR. The standard examination takes approximately 15 minutes to complete; after that, the research MR scans will be performed. Standard clinical MRI of the head will be repeated on an annual basis and read by the Diagnostic Radiology Department of the Clinical Center.

Intervention type: PROCEDURE
Group type: PLACEBO_COMPARATOR
Intervention: Peripheral Nerve Stimulation
Description: Constant-current, 0.1 to 0.5 ms square-wave single pulses of electrical stimulation will be delivered through standard bar electrodes to nerves of the upper limb or of the lower limb. To study somatosensory evoked potentials, for example, the stimulus intensity will be set at just above the motor threshold for evoking a slight limb movement. Location of the electrical stimulation will depend on the specific objective of the sub-study. Peripheral nerve stimulation might be delivered during other types of experiments as well.

Intervention type: PROCEDURE
Group type: ACTIVE_COMPARATOR
Intervention: Peripheral Nerve Stimulation
Description: Constant-current, 0.1 to 0.5 ms square-wave single pulses of electrical stimulation will be delivered through standard bar electrodes to nerves of the upper limb or of the lower limb. To study somatosensory evoked potentials, for example, the stimulus intensity will be set at just above the motor threshold for evoking a slight limb movement. Location of the electrical stimulation will depend on the specific objective of the sub-study. Peripheral nerve stimulation might be delivered during other types of experiments as well.

Intervention type: PROCEDURE
Group type: PLACEBO_COMPARATOR
Intervention: EMG
Description: EMG measures the electrical activity of muscles. For our research purposes, only surface EMG will be used to measure the effects of central and peripheral nervous system stimulation. For surface EMG, electrodes will be coated with a conductive gel and taped to the skin. For motor evoked potential (MEP) acquisition during TMS, electrodes will be placed over the belly and the tendon of the distal muscles of the hand or foot and/or proximal muscles.

Intervention type: PROCEDURE
Group type: ACTIVE_COMPARATOR
Intervention: EMG
Description: EMG measures the electrical activity of muscles. For our research purposes, only surface EMG will be used to measure the effects of central and peripheral nervous system stimulation. For surface EMG, electrodes will be coated with a conductive gel and taped to the skin. For motor evoked potential (MEP) acquisition during TMS, electrodes will be placed over the belly and the tendon of the distal muscles of the hand or foot and/or proximal muscles.

Intervention type: PROCEDURE
Group type: PLACEBO_COMPARATOR
Intervention: Trancutaneous spinal direct current stimulation (tsDCS)
Description: Direct current (DC) stimulation is a non invasive tool used to promote plasticity of the central nervous system. Recently, DC stimulation has been applied to the human spinal cord, and known as transcutaneous spinal direct current stimulation (tsDCS).

Intervention type: PROCEDURE
Group type: ACTIVE_COMPARATOR
Intervention: Trancutaneous spinal direct current stimulation (tsDCS)
Description: Direct current (DC) stimulation is a non invasive tool used to promote plasticity of the central nervous system. Recently, DC stimulation has been applied to the human spinal cord, and known as transcutaneous spinal direct current stimulation (tsDCS).