Concurrent TMS and EEG Pilot Study
Condition: Healthy
Study type: Interventional

Summary: 
      This study will investigate the test-retest reliability of transcranial magnetic stimulation
      (TMS) -evoked potentials (TEPs) as measured by electroencephalography (EEG), using three
      different TMS protocols over five different brain regions in healthy volunteers. The goal is
      to compare the test-retest reliability of single pulse, inhibitory and excitatory TMS
      protocols as well as two distinct targeting approaches. The main questions to answer are:

        1. This study will investigate whether the test-retest reliability of TEPs differ across
           TMS protocols.

        2. This study will investigate whether the test-retest reliability of TEPs differ between
           individualized and non-individualized targeting approaches.
    

Detailed description: 
      Participants will first undergo functional magnetic resonance imaging (fMRI) scanning where
      structural and resting-state functional images will be obtained. In two separate sessions,
      participants will attend two concurrent TMS/EEG session with one week in between.

      During the TMS/EEG sessions, an EEG cap will be placed on the participant's head and the
      resting motor threshold will be obtained to calibrate the TMS intensity required for the
      stimulation of target regions. Once setup procedures are complete, eleven total blocks of TMS
      with simultaneous EEG recording will take place. Among eleven blocks, five of will use
      single-pulse stimulation (to stimulate cortical excitation), three will use paired-pulse
      stimulation with 3ms between pulses (to stimulate cortical inhibition), and three will use
      paired-pulse stimulation with 11ms between pulses (to stimulate greater cortical excitation).
      Five different brain regions will be targeted: three individualized targets either derived
      anatomically (motor cortex) or based on the individual's resting-state functional
      connectivity (dorsolateral prefrontal cortex and angular gryus) and two regions that are
      based on the literature (dorsolateral prefrontal cortex and angular gryus).
    

Intervention name(s): Concurrent transcranial magnetic stimulation and electroencephalogram
Intervention type(s): Device
Intervention description(s): Single and paired-pulse TMS will be applied to 5 different brain regions during simultaneous recording of EEG. Paired-pulse stimulations will have either 3 ms or 11 ms between pulses, to stimulate cortical inhibition and excitation respectively. Stimulation intensity for single-pulse stimulation blocks will be 120% of the resting motor threshold (RMT). For paired-pulse blocks, the conditioning (first) pulse will be delivered at a stimulation intensity of 80% RMT, and the test (second) pulse will be delivered at 120% RMT. Each test block will consist of 60 TMS trials and will last for 5 minutes. Order of test blocks will be pseudo-randomized across participants. Out of 5 stimulation sites, 3 will be determined based on individual's own brain anatomy and resting state connectivity. These 3 regions will be stimulated using all 3 TMS protocols. The other two regions will be determined based on the literature and only be targeted using the single pulse TMS protocol.
Intervention model: Single Group Assignment
Intervention model description: Within-subject design. Each participant will undergo the same TMS/EEG procedures twice with one week in between sessions.
Masking: None (Open Label)
Primary purpose: Basic Science