Neural Correlates of Observation of Tactile Stimulation in Healthy Subjects
Condition: Healthy
Study type: Observational

Summary: 
      This study will examine activity in the brain during the observation of touch. Studies with
      animals have shown that mirror neurons, or nerve cells, are active during the observation and
      performance of an action. The researchers for this study hypothesize that a similar system
      pertains to observing and experiencing touch.

      Patients ages 18 to 75 years old who are in good health, are right handed, and who are able
      to perform simple tasks that require attention may be eligible for this study. Pregnant women
      are not eligible.

      Patients who have not had a health screening at NIH will undergo a clinical and neurological
      exam. Women of childbearing potential will also have a pregnancy test. The screening will
      take about 2 to 3 hours. A diagnostic magnetic resonance imaging (MRI) scan will be performed
      if patients have not undergone one in the previous 12 months. During the procedure, patients
      will lie still on a table that will slide into the enclosed tunnel of the scanner. They will
      be asked to lie as still as possible for up to a few minutes at a time. As the scanner takes
      pictures, patients will hear knocking or beeping sounds, and they will wear earplugs to
      reduce the noise. Patients will be able to communicate with the MRI staff at all times during
      the scan, and they may ask to be moved out of the machine at any time. This scan will take
      about 2 hours.

      Two sessions are involved in the study. The first one is intended to familiarize patients
      with the procedure. During it, they will learn about hand stimulus, through watching a video
      showing the index finger of a hand being touched by a stick repeatedly. Then the activity
      will be repeated, but this time, a researcher will also touch the patient's index finger
      while he or she is watching the video. This session will take about 1 hour.

      The second session consists of a functional MRI scan, or fMRI. During it, pictures of the
      brain will be taken while patients perform tasks. All tasks will be explained in advance, and
      patients will have an opportunity to practice them before entering the scanner. The fMRI scan
      will take 1 to 2 hours.

      The researchers will discuss the results of the tests with the participants. There is not a
      direct benefit to those who take part in the study. However, it is hoped that resulting
      information will enhance researchers' understanding about how the brain processes observed
      information.
    

Detailed description: 
      Objective:

      There is growing evidence that a mirror system for action observation exists. Neurons in the
      monkey premotor cortex discharge with performance of goal directed actions and also with
      observation of another individual performing a similar action. This mirror neuron system for
      action observation seems to be important for the recognition and understanding of actions.
      Recently, bimodal neurons, sensitive both for tactile stimulation and for visual stimuli,
      were found in the parietal cortex. This suggests the idea that there might be a similar
      mirror neuron system for observing and receiving (or experiencing) tactile stimulation. The
      neuronal correlates of observing tactile stimulation are mainly unknown. The purpose of this
      protocol is to determine the pattern of brain activation related to the observation of a
      tactile stimulated hand.

      Study Population:

      We will test our hypothesis by means of a functional MRI (fMRI) experiment in a group of
      healthy subjects.

      Design:

      We hypothesize that observation of touch will rely on the activation of a cortical network
      that is different form the observation of non-touch and is in part overlapping with cortical
      structures active during real tactile stimulation (i.e., somatosensory cortex). Further, we
      hypothesize that the observation of touch enhances activation in the somatosensory cortex
      during real tactile stimulation.

      Outcome Measures:

      Our outcome measure will be an increase in the number of activated voxels in the
      somatosensory cortex during the touch observation (for both hypothesis). This would give an
      important hint for a mirror system for observed and received touch. A mirror neuron system
      for observed touch may become an important tool in rehabilitative treatment for patients with
      somatosensory impairments.
    

Keywords: fMRI; Mirror Neuron System; Bimodal Neurons; Somatosensory Cortex; Rehabilitation; Healthy Volunteer; HV