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

Metaplasticity in the Human Motor Cortex: Validation of an Experimental Design and Comparison of Motor Outcome Measure Sensitivity to Change

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.

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.

Participants will be blinded to treatment group, investigator administering tDCS will be blinded to which treatment arm subject is assigned to, and the data analyst will be conducting analysis off site and is different than investigator applying stimulation.

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.

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.

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.

Between time point M2 and M3, participant will receive 900 pulses of rTMS at 1Hz at 0.85 of M2 resting motor threshold.

assessed and reported throughout study completion pre- and post- intervention approximately 30 minutes

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.

Inclusion Criteria: Must be at least 18 years of age (all genders, races, ethnicity) Must have no current psychiatric or neurologic issues Must not have any conditions listed in exclusion criteria Must be fluent in English 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