Metaplasticity in the Human Motor Cortex 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. 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.

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