Competition between frontal lobe functions and implicit sequence learning: evidence from the long-term effects of alcohol.

Implicit sequence learning is a fundamental mechanism that underlies the acquisition of motor, cognitive and social skills. The relationship between implicit learning and executive functions is still debated due to the overlapping fronto-striatal networks. According to the framework of competitive neurocognitive networks, disrupting specific frontal lobe functions, such as executive functions, increases performance on implicit learning tasks. The aim of our study was to explore the nature of such a relationship by investigating the effect of long-term regular alcohol intake on implicit sequence learning. Since alcohol dependency impairs executive functions, we expected intact or even better implicit learning in patient group compared to the healthy controls based on the competitive relationship between these neurocognitive networks. To our knowledge, this is the first study to examine the long-term effects of alcohol dependency both on implicit learning and on executive functions requiring different but partly overlapping neurocognitive networks. Here, we show weaker executive functions but intact implicit learning in the alcohol-dependent group compared to the controls. Moreover, we found negative correlation between these functions in both groups. Our results confirm the competitive relationship between the fronto-striatal networks underlying implicit sequence learning and executive functions and suggest that the functional integrity of this relationship is unaltered in the alcohol-dependent group despite the weaker frontal lobe functions.