Action inhibition in Tourette syndrome

Abstract

Tourette syndrome is a neuropsychiatric disorder characterized by tics. Tic generation is often linked to dysfunction of inhibitory brain networks. Some previous behavioral studies found deficiencies in inhibitory motor control in Tourette syndrome, but others suggested normal or even better-than-normal performance. Furthermore, neural correlates of action inhibition in these patients are poorly understood. We performed event-related functional magnetic resonance imaging during a stop-signal reaction-time task in 14 uncomplicated adult Tourette patients and 15 healthy controls. In patients, we correlated activations in stop-signal reaction-time task with their individual motor tic frequency. Task performance was similar in both groups. Activation of dorsal premotor cortex was stronger in the StopSuccess than in the Go condition in healthy controls. This pattern was reversed in Tourette patients. A significant positive correlation was present between motor tic frequency and activations in the supplementary motor area during StopSuccess versus Go in patients. Inhibitory brain networks differ between healthy controls and Tourette patients. In the latter the supplementary motor area is probably a key relay of inhibitory processes mediating both suppression of tics and inhibition of voluntary action.

Increased beta rhythm as an indicator of inhibitory mechanisms in tourette syndrome

“…Less sensorimotor beta desynchronization shown by TS patients contralaterally to the responding hand is in keeping with the assumption of increased tonic inhibition in these patients, probably to suppress tics. 5 Beta upregulation in the motor cortex was associated with improved behavioral outcome in a holding contraction task in healthy subjects. 20 The beta FIG.…”

Functional neuroimaging in Tourette syndrome: recent perspectives

“…Another study showed a reduced activation in the dorsal premotor cortex for the StopSuccess trial. 21 The conflicting results might be caused by a difference in study design: in Ganos et al's study, 21 the procedure was adapted to ensure a fifty-fifty successful performance in the no-go trials in both patients and controls, whereas in Thomalla et al's study, 22 there were behavioral differences between patients and controls. The patients with TS were slower and and made more mistakes in no-go trials than the healthy controls.…”

“…21,22 Go/ no-go test is a test of behavioral control in which an appropriate reaction must be performed and an inappropriate reaction must be inhibited. Results are contradictory.…”

“…With regard to the fMRI studies, for example, one study has used resting state networks, 12 while another has used regional homogeneity. 19 The fMRI tasks themselves can have had different paradigms, 21,22 but also the same tasks can have been performed in different ways -eg, finger tapping with preferred or nonpreferred hand or imaginary finger …”

Stopping Manual and Vocal Actions in Tourette’s Syndrome

“…These cortical regions, along with their connections to the basal ganglia, comprise the brain's inhibitory control network, a network that is variably impacted in adults with persistent TS. 10,35 Moreover, Ganos et al 36 identified functional changes in this network between TS and controls performing a stop-signal task. It should be recognized that several measures of inhibitory control used in the TS literature are not entirely interchangeable, but capture distinct forms of inhibitory control associated with dissociable neural mechanisms.…”