Metaplasticity Experimental Design and Comparison of Motor Outcome Measure Sensitivity to Change

Not Applicable

Completed

Brief Summary: The overall objective is to validate the methodology of a metaplasticity experimental design by assessing change in motor excitability after administration of priming transcranial direct current stimulation (tDCS) followed by repetitive transcranial magnetic stimulation (rTMS) in healthy human participants.

Detailed Description: The overall objective is to validate the methodology of a metaplasticity experimental design by assessing change in motor excitability after administration of priming transcranial direct current stimulation (tDCS) followed by repetitive transcranial magnetic stimulation (rTMS) in healthy human participants. Our primary objective is to compare pre- and post-measures of cortical excitability before priming tDCS (anodal, cathodal or sham) \[M1\], directly after priming tDCS \[M2\], directly after inhibitory rTMS \[M3\], and 10 minutes after inhibitory rTMS \[M4\]. Our secondary objective is to evaluate the sensitivity of motor excitability outcome measures response to the noninvasive neurostimulation (e.g. rTMS and tDCS). We also aim to compare pre- and post- measures of cortical excitability after inhibitory and excitatory priming of the motor cortex, and to evaluate the sensitivity of motor outcome measures to changes in cortical plasticity.

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

History of major psychiatric illness
Actively using neuropsychoactive medication
Legal or mental incompetency
Substance use disorder, abuse or dependence, with active use within the last three months
Significant medical or neurological illness
Prior neurosurgical illness
Prior neurosurgical procedure
History of seizure
History of ECT or TMS treatment within the past there months
Presence of a pacemaker, implanted medical pump or device, metal plate, or metal object in skull or eye (including shunts, dental implants, facial tattoos with metallic ink)
Pregnant women

Arm && Interventions

Group	Intervention	Description
Anodal tDCS + rTMS then Sham tDCS + rTMS then Cathodal tDCS + rTMS	rTMS	Participant will receive 10 minutes of anodal tDCS between M1 and M2 timepoints, and rTMS for 900 1Hz pulses at 0.85 of Resting Motor Threshold at M2. After 1 week washout, participant will receive 10 minutes of sham tDCS and rTMS for 900 1 Hz pulses at 0.85 RMT. After 1 week washout, participant will receive 10 minutes of cathodal tDCS and rTMS for 900 1 Hz pulses at 0.85 RMT.
Cathodal tDCS + rTMS then Anodal tDCS + rTMS then Sham tDCS + rTMS	rTMS	Participant will receive 10 minutes of cathodal tDCS between M1 and M2 timepoints, and rTMS for 900 1Hz pulses at 0.85 of Resting Motor Threshold at M2. After 1 week washout, participant will receive 10 minutes of anodal tDCS and rTMS for 900 1Hz pulses at 0.85 RMT. After 1 week washout, participant will receive 10 minutes of sham tDCS and rTMS for 900 1 Hz pulses at 0.85 RMT.
Sham tDCS + rTMS then Cathodal tDCS + rTMS then Anodal tDCS + rTMS	rTMS	Participant will receive 10 minutes of sham tDCS between M1 and M2 timepoints, and rTMS for 900 1Hz pulses at 0.85 of Resting Motor Threshold at M2. After 1 week washout, participant will receive 10 minutes of cathodal tDCS and rTMS for 900 1 Hz pulses at 0.85 RMT. After 1 week washout, participant will receive 10 minutes of anodal tDCS and rTMS for 900 1 Hz pulses at 0.85 RMT.

Primary Outcome Measures

Name	Time	Method
Percent Change in MEP Amplitude	assessed and reported throughout study completion pre- and post- intervention approximately 30 minutes	Percent Change in MEP amplitude over the first dorsal interosseous (FDI) muscle of the right hand

Secondary Outcome Measures

Name	Time	Method
Cortical Silent Period	tDCS + rTMS assessed and reported pre and post (approximately 10 minutes)	Change in length of CSP
Simple Reaction Time	The final outcome will be percent change in the reaction time from pre- to post- intervention.	Participants will perform a simple reaction time task. This will be measured in seconds of response after a stimulus. The final outcome will be percent change in the reaction time from pre- to post- intervention.