Inhibitory control and voluntary tic suppression.

Tics, such as those seen in Tourette syndrome (TS), are brief, sudden, and involuntary movements or vocalizations. Although tics are involuntary, most individuals with TS can suppress them on command for short periods of time. This capacity, which is called voluntary tic suppression, is a hallmark feature of TS and differentiates it from most other movement disorders. Several studies have investigated inhibitory control of voluntary actions in TS, given its potential associations with both tic expression and voluntary tic suppression. However, studies on response inhibition in TS have produced quite mixed results. Furthermore, the mechanisms of voluntary tic suppression remain poorly understood. The current chapter offers an overview of the evidence related to inhibitory control of voluntary actions and voluntary tic suppression in TS. It reviews evidence from clinical, behavioral, neuropsychologic, and neurobiologic studies in order to understand to what extent these processes may be similar or different.