Exploring the Relationship Between Brain Asymmetry and Attention
Condition: Normal Physiology
Study type: Interventional

Summary: 
      Background:

      People tend to pay more attention to one side of space than the other and this may be due to
      differences in the structure and function of the two sides of the brain. We are interested in
      whether we can detect those difference with magnetic resonance imaging (MRI), transcranial
      magnetic stimulation (TMS), and electroencephalography (EEG).

      Objective:

      The purpose of the study is to understand how differences in brain structure may cause people
      to pay more attention to one side than the other.

      Eligibility:

      Healthy adults ages 18-35

      Design:

      Participants will be screened with a neurological exam.

      Participants will have 2-3 visits for a total duration of about 7/8 hours.

      Women of childbearing age must have a negative pregnancy test before each MRI scan.

      Visits may include:

      Physical exam

      Tests of attention, and thinking

      TMS. A brief electrical current will pass through a wire coil on the scalp. Participants will
      hear a click and may feel a pull. They may be asked to tense muscles or do tasks.

      Magnetic resonance imaging (MRI) scan for a maximum of 1 hour. Participants will lie on a
      table that slides into a cylinder in a strong magnetic field. They will do tasks on a
      computer screen or lie still. They will get earplugs for loud noise.

      EEG for no longer than 5 hours, with most lasting 3 hours. Gel and a cap with electrodes will
      be placed on the scalp. They will record brain waves while the participant gets TMS or does
      nothing.

      Questions about participants dominant hand and about the MRI.
    

Detailed description: 
      Objective

      The goal of this protocol to explore correlations between lateralized individual differences
      in visual attentional preference and hemispheric asymmetries in functional connectivity
      between the frontal and parietal visual attention areas. To measure functional connectivity,
      resting state functional MRI and electroencephalographic (EEG) potentials evoked with
      transcranial magnetic stimulation (TMS) will be used. Protocol research will also attempt to
      validate the TMS-evoked EEG potentials against fMRI resting state functional connectivity.

      Study Population

      Up to 80 right-handed and right-eyed healthy volunteers, aged 18-35

      Design

      TMS evoked EEG potentials (TEPs) and fMRI will be used to measure functional connectivity
      between the posterior parietal cortex and the frontal visual attention area. Various tasks
      will be used to quantify attention and explore their relationship with asymmetries in
      functional connectivity. A qualitative comparison between the value of fMRI and TEPs for
      predicting attentional bias will be made.

      Outcome Measures

        -  Behavioral measures of attention

        -  TEP measures of functional connectivity

        -  fMRI measures of functional connectivity
    

Intervention name(s): TMS EEG; TMS fMRI
Intervention type(s): Device; Device
Intervention description(s): attempt to use TMS EEG to measure connectivity between cortical areas; compare measurements to established functional connectivity measures; e.g., EEG coherence and fMRI
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: TMS-Evoked Potential; TMS; fMRI; Behavior; Electroencephalogram (EEG)