Brain structural substrates of cognitive procedural learning in alcoholic patients early in abstinence.

BACKGROUND: Procedural learning allows for the acquisition of new behavioral skills. Previous studies have shown that chronic alcoholism is characterized by impaired cognitive procedural learning and brain abnormalities affecting regions that are involved in the automation of new cognitive procedures in healthy individuals. The goal of the present study was to investigate the brain structural substrates of cognitive procedural learning in alcoholic patients (ALs) early in abstinence.

METHODS: Thirty-one ALs and 31 control participants (NCs) performed the Tower of Toronto task (4 daily learning sessions, each comprising 10 trials) to assess cognitive procedural learning. We also assessed episodic and working memory, executive functions, and visuospatial abilities. ALs underwent 1.5T structural magnetic resonance imaging.

RESULTS: The initial cognitive phase was longer in the AL group than in the NC group, whereas the autonomous phase was shorter. In ALs, the longer cognitive phase was predicted by poorer planning and visuospatial working memory abilities, and by smaller gray matter (GM) volumes in the angular gyrus and caudate nucleus. ALs' planning abilities correlated with smaller GM volume in the angular gyrus.

CONCLUSIONS: Cognitive procedural learning was impaired in ALs, with a delayed transition from the cognitive to the autonomous phase. This slowdown in the automation of the cognitive procedure was related to lower planning abilities, which may have hampered the initial generation of the procedure to be learned. In agreement with this neuropsychological finding, a persistent relationship was found between learning performance and the GM volumes of the angular gyrus and caudate nucleus, which are usually regarded as markers of planning and initial learning of the cognitive procedure.