Abnormalities of Neural Microcircuits in Tourette Syndrome

Abstract

Abstract Transcranial magnetic stimulation (TMS) coupled with electromyography allows for extensive study of the motor system and related microcircuits. By varying TMS intensity and interval between pulses, it is possible to probe a number of physiological mechanisms. In contrast to magnetic resonance imaging approaches, TMS is less sensitive to motion. However, although data loss due to movement can be minimized in TMS studies, the impact of potential tic suppression should be considered while interpreting this work, as should the challenges of attempting to define what constitutes a rest state in TS. Complex interactions across numerous circuits, between causal and consequential adaptations and states of activation and rest, are likely and require much additional research to disentangle. In addition to being a useful tool for understanding microcircuits, forms of TMS have been explored as potential therapeutic interventions, as has transcranial direct current stimulation. The evidence for effectiveness of these treatments is mixed, and they are currently not recommended outside of experimental trails. Larger scale studies with appropriate controls are needed to better understand if and how these approaches can help reduce tics.