Brain Dynamics Involved in Generating Tics and Controlling Voluntary Movement
Condition: Tourette Syndrome; Tic Disorders
MeSH terms: Tourette Syndrome; Tics; Tic Disorders; Syndrome
Study type: Observational

Summary: 
      This study will use electroencephalography (EEG) and electromyography (EMG) to examine how
      the brain generates tics and controls voluntary movement in patients with Tourette's syndrome
      and chronic motor tic disorder. EEG records the electrical activity of the brain. For this
      test, a cap with built-in electrodes is placed on the subject's head, and the electrodes are
      connected to a monitor that records the brain activity. EMG records muscle activity using
      electrodes placed on the skin over muscles on the fingers or above the outer corner of the
      eyes.

      Healthy normal volunteers and patients with Tourette's syndrome and chronic motor tic
      disorder between 21 and 65 years of age may be eligible for this 2- to 3-hour study. Each
      candidate will be screened with a medical history, physical and neurological examinations,
      and a questionnaire that screens for psychiatric disorders.

      During EEG and EMG recordings, participants undergo the following tasks while seated
      comfortably in a sound-shielded room:

      Patients

        -  Finger task: Patients raise their index finger once every 10 seconds for about 25
           minutes.

        -  Tic evaluation and mimicking: Patients allow their tics to occur as they do naturally.
           After each tic, they report whether the tic was voluntary and whether it was preceded by
           a sensation of urge. They then mimic tics that they normally have, at a rate of about
           once every 10 seconds.

        -  Tic suppression task: Patients suppress tics they normally have for several minutes.
           They then allow the tics to occur naturally, without attempting to suppress them.

      Normal Volunteers

        -  Finger task: Volunteers raise their index finger once every 10 seconds for about 25
           minutes.

        -  Open eye task: Volunteers keep their eyes open for a minute or so, and then resume
           blinking as often as feels comfortable. The process is repeated several times.
    

Detailed description: 
      This study examines the spatiotemporal dynamics of cortical functional interconnectivity
      involved tics and voluntary movement in patients with Tourette's syndrome or chronic motor
      tic disorder. By employing a combination of EEG methods that utilize analyses in the domains
      of both frequency (e.g., event-related desynchronization/synchronization (ERD/ERS),
      event-related partial coherence, phase coherence) and time (e.g., event-related partial
      correlation), we intend to determine

        1. Whether the cortical neurocircuitry involved in the performance of a simple, voluntary
           motor task differs in patients with tic disorders from that of healthy volunteers;

        2. Whether the network involved in the generation of unwanted tics differs from that of
           normal voluntary movement (i.e., mimicked tics); and

        3. What role, if any, premonitory urge and/or tic suppression plays in the modulation of
           this neurocircuitry.
    

Keywords: Tourette's Syndrome; Tic Disorder; (EEG) Electroencephalography; Event-Related Desynchronization/Synchronization; Coherence; Tourette's; Tourette Syndrome; Healthy Volunteer; HV