Task-dependent Effects of TMS on the Neural Biomarkers of Episodic Memory
Condition: Normal Physiology
Study type: Interventional

Summary: 
      Background:

      Transcranial magnetic stimulation (TMS) of the brain has been used to change the activity and

      connections in the brain to improve memory. Researchers are interested in how these brain
      changes cause memory improvements and how activity at the time of stimulation may change the
      effects of TMS.

      Objective:

      To learn how brain stimulation can be used to improve memory.

      Eligibility:

      Healthy adults ages 18-40

      Design:

      Participants will be screened with a medical record review.

      Participants will have 3 study visits.

      At visit 1, participants will have a physical exam and will talk about their health. They
      will have magnetic resonance imaging (MRI). The MRI scanner is a metal cylinder surrounded by
      a strong magnetic field. During the MRI, participants will lie on a table that can slide in
      and out of the scanner. A coil will be placed over the head. Participants will be asked to
      keep their eyes focused on a small cross on a computer screen inside the scanner. The scanner
      makes loud noises. Participants will get earplugs.

      At visits 2 and 3, participants will have TMS and perform tasks. For TMS, a wire coil encased
      in plastic is held on the scalp. When the coil is triggered, a brief electrical current
      passes through the coil and creates a magnetic pulse that stimulates the brain. During TMS,
      an electroencephalogram (EEG) will record brain activity. For the EEG, a cloth cap with
      electrodes is fitted on the participant s head. Participants will complete a memory task and
      a spatial processing task. They will also complete surveys about their mental state.

      Participation will last 2-3 weeks.

      ...
    

Detailed description: 
      Study Description:

      The Behavioral Neurology Unit studies the human brain systems underlying learning and
      adaptation with the goal of finding interventions to make these processes more efficient. In
      this study, we are interested in examining how the task state of the episodic memory network
      influences the effect of faciliatory TMS on memory and its EEG neural correlates. It is
      hypothesized that Network-targeted parietal-TMS will improve memory performance and enhance
      EEG biomarkers of successful memory performance, but that these changes will be modulated by
      the ongoing task activity

      during stimulation.

      Objectives:

      Primary Objectives:

        -  Investigate how TMS modulates EEG neural measures of successful memory and the
           association of this modulation with behavioral performance

        -  Examine how memory task state influences susceptibility to plasticity via TMS and
           determine the optimal neural state for improving memory

      Exploratory Objectives:

      -Search for MRI predictors of the effects of TMS

      Endpoints:

        -  Primary Endpoints: Memory performance, Late Positive Posterior ERP, evoked theta/alpha
           power (secondary), EEG functional connectivity (secondary)

        -  Exploratory Endpoints: fMRI resting state functional connectivity, fractional anisotropy
    

Intervention name(s): TMS
Intervention type(s): Device
Intervention description(s): The intervention of interest will be TMS delivered to the region of the left posterior parietal cortex with the greatest connectivity with the left hippocampus derived from the baseline resting-state fMRI session. This region was chosen because of its dense connections with the hippocampus, allowing stimulation of this location to modulate function of the hippocampal-cortical network. The control intervention target will be vertex, a commonly used active control site which does not influence neural or behavioral activity.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Memory performance; Neural Biomarkers; EEG; Noninvasive transcranial magnetic stimulation