Functional magnetic resonance imaging of tics and tic suppression in Gilles de la Tourette syndrome.

Tics are defined as involuntary, quick, sudden, and stereotypical movements or phonic productions. Despite the fact that tic suppression plays an important role for the patient's ability to cope with tic disorders, investigations of the underlying neural correlates using functional imaging focused on tic generation rather than tic suppression. We examined a patient with Gilles de la Tourette syndrome with regard to neural mechanisms of tic generation and tic suppression using fMRI. Three different conditions were compared: "tics", "tics suppressed", and "tics imitated". The comparisons of "tics" to tics suppressed" and of "tics" to "tics imitated" showed similar activation in the anterior cingulate cortex. This leads to distinct suggestions concerning the neural network involved in tic suppression. Similar mechanisms may be involved in tic suppression via mental efforts or active movements.