Timing of Voluntary Movement in Patients With Tourette Syndrome and Chronic Tic Disorder
Condition: Tourette Syndrome; Tic Disorders
MeSH terms: Tourette Syndrome; Tics; Tic Disorders; Syndrome
Study type: Observational

Summary: 
      This study will examine how the brain controls movement in people with Tourette syndrome and
      chronic tic disorder to determine if the timing of movement is important in whether someone
      feels "in control" of their movements. Although movements in tic disorders are often
      characterized as "involuntary," some patients claim that these movements are made
      voluntarily, or they are unable to decide if they are voluntary or involuntary. Previous
      experiments have shown that when people are asked to look at a clock and report the time they
      first decide to make a movement they report times later than the first brain waves associated
      with movement appear. When they are asked to report the time they first initiate the
      movement, they report times before the muscles actually begin to move. This study may help
      determine how the sense of willing and initiating an action is altered in patients with
      Tourette syndrome and chronic tic disorder, and how people may feel more or less "in control"
      of their movements.

      Normal volunteers and patients with Tourette syndrome or chronic tic disorder between 18 and
      65 years of age may be eligible for this study. Control subjects must not have any
      neurological or psychological disorders, and patients with Tourette syndrome of chronic tic
      disorder must not have any other neurological disorders. Patients with attention deficit
      hyperactivity disorder (ADHD) may not enroll in this study.

      All participants will have a medical history, physical examination, and a test to determine
      their level of attention. Patients will be interviewed about their symptoms and complete
      psychiatric rating scales. In addition, all participants will undergo the following
      procedures:

      Electric shock

      Participants look at a clock on a computer screen, the hands of which revolves quickly. While
      looking at the clock, each participant will be given small, non-painful electric shocks and
      asked, according to the clock, to say when they received the shocks. The shocks are repeated
      40 times.

      Arm movement

      Participants are asked to lift their arms off a table repeatedly, at random times, while they
      look at the computer clock. This exercise is repeated 80 times. Of these 80, participants are
      asked 10 times consecutively to say the time they first had the desire to move their arm, and
      then 10 consecutively the time they first felt that they were moving their arm.

      Electroencephalography (EEG) and Electromyography (EMG)

      Participants undergo EEG and EMG durin...
    

Detailed description: 
      OBJECTIVES: The purpose of this study is to determine how the subjective sense of willing and
      initiating an action is altered in patients with Tourette Syndrome and Chronic Tic Disorder.
      Although many definitions of the disease include the characterization of tics as
      'involuntary', some patients claim that these movements are voluntarily made, or are unable
      to decide if they are voluntary or involuntary. Recent studies have shown that the time order
      in which someone wills a voluntary movement and begins that movement is central to the
      subjective sense of causality. We propose to examine tics as well as normal, voluntary
      movements in patients with Tourette Syndrome and Chronic Tic Disorder to identify the time
      course between the decision to move and the onset of movement. Using Libet's paradigm, we
      intend to have subjects watch a fast-rotating clock to report the times associated with
      willing (time W) and initiating (time M) movement; we will also determine
      electroencephalographic/electromyographic (EEG/EMG) measures of movement.

      STUDY POPULATION: We intend to study adult patients with a Diagnostic and Statistical Manual
      of Mental Disorders diagnosis of a tic disorder and frequent tics as well as normal, healthy
      volunteers as controls.

      DESIGN: We will ask tic patients to rate the "voluntariness" of their tics using a rating
      scale. We will ask tics patients to look at a fast-rotating clock on a computer screen and
      note when their movements were willed (time W) and were initiated (time M), for tics as well
      as normal voluntary movements. Patients will also report the time of a somatosensory
      stimulus. Surface EMG will determine the time of actual movement, and EEG will record brain
      potentials associated with movement. The design will be the same for the normal volunteers
      with the exception that the volunteers will not complete rating scales and will not be
      experiencing tics.

      OUTCOME MEASURES: The primary outcome measure of this study is the latency of times W and M
      (before EMG onset) in tics patients as correlated with the voluntariness the patients
      associate with their tics, compared to the time W and M reported for normal voluntary
      movements in the normal volunteers.
    

Keywords: Bereitschaftspotential; Timing of Volition; Urge; Conscious Will; Libet's Clock; Tourette Syndrome; Tic Disorder; Healthy Volunteer; HV