Procedural memory, which is rooted in the basal ganglia, underlies the learning and processing of numerous automatized motor and cognitive skills, including in language. Not surprisingly, disorders with basal ganglia abnormalities have been found to show impairments of procedural memory. However, brain abnormalities could also lead to atypically enhanced function. Tourette syndrome (TS) is a candidate for enhanced procedural memory, given previous findings of enhanced TS processing of grammar, which likely depends on procedural memory. We comprehensively examined procedural learning, from memory formation to retention, in children with TS and typically developing (TD) children, who performed an implicit sequence learning task over two days. The children with TS showed sequence learning advantages on both days, despite a regression of sequence knowledge overnight to the level of the TD children. This is the first demonstration of procedural learning advantages in any disorder. The findings may further our understanding of procedural memory and its enhancement. The evidence presented here, together with previous findings suggesting enhanced grammar processing in TS, underscore the dependence of language on a system that also subserves visuomotor sequencing.

Children with autism spectrum disorder (ASD) show altered learning and memory. A number of recent studies have debated whether procedural learning in ASD is intact or not. Our aim was to further assess the question of whether the implicit, non-conscious form of procedural learning in ASD children is intact or not, furthermore, how shifts towards a more explicit, attention-demanding task setting can alter this performance. We administered a modified version of the Alternating Serial Reaction Time (ASRT) Task to children with ASD and IQ- and age-matched typically developing (TD) children. The task consisted of alternating blocks of cued (explicit) and uncued (implicit probe) blocks, and was repeated after a 16-hour delay. We found that ASD and TD children showed similar sequence-specific learning in cued explicit blocks, however, on the uncued probe blocks ASD children performed better compared to TD children. After the 16-hour delay both groups showed retention of the previously acquired knowledge. Finally, when we investigated the performance in different parts of the blocks, we found that ASD children did not show an effect of fatigue by the second part of the blocks. Our results suggest that children with ASD have increased implicit procedural learning skills compared to TD children. Differences in cued (explicit) and uncued (implicit) settings indicate that children with ASD are not affected by the lack of explicit instructions in probe blocks, suggesting a resistance for changes in task settings. These findings can help in a more thorough planning of cognitive therapeutic setups for ASD children.