How do alterations of the basal ganglia affect procedural memory in Tourette syndrome?*

Tourette syndrome (TS) is a childhood-onset neurodevelopmental disorder characterized by repetitive movements and vocalizations called tics, which are linked to alterations in the cortico-basal ganglia-thalamo-cortical (CBGTC) circuits. CBGTC circuits also play a key role in procedural memory, which is a fundamental human ability that enables us to extract repeating patterns from the environment and underlies skill-based and habitual behavior. The present review summarizes findings on procedural memory in TS, with a focus on more recent studies probing the acquisition and consolidation of procedural knowledge in TS. The review reveals mixed findings; some aspects of procedural memory seem to be impaired in TS, whereas other aspects appear intact or even enhanced. We discuss these results in relation to alterations in the CBGTC circuits in TS, suggest reasons for potential inconsistencies across studies, and propose directions for future research.