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Lorenz Deserno

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RLDM Conference 2013 Conference Abstract

Modeling of Cognitive Impairment in Reversal Learning after Chronic Alcohol Use

  • Sinem Balta Beylergil
  • Lorenz Deserno
  • Anne Beck
  • Klaus Obermayer
  • Andreas Heinz

Reversal learning paradigm, where subjects must learn to respond to formerly irrelevant stimulus- reward pairing, has been used in many studies to explore the adverse effects of addiction on decision making and learning. However, the focus has been more on error pattern analyses and the underlying computational principles have not been analyzed in depth as far as alcohol addiction is concerned. In this study, we used behavioral computational modeling to shed light on the impaired mechanisms of decision making in alcohol addiction. 35 abstinent alcohol-dependent and 26 control subjects (age, sex and IQ matched) performed a probabilistic reversal task. We considered three computational learning models: (1) a simple reinforcement learning (RL) model, (2) a variant of the RL model and (3) a Hidden Markov model (HMM). Additionally, each model had two variants: the first with equal and the second with unequal free parameters assigned to positive and negative outcomes. The results showed that AG scores worse overall than CG and needed more trials to reach the reversal criteria. At the time of reversals, AG shifted their response later than CG, showing difficulty in inhibitory control. The equally best fitting models (2) and (3) both illustrated that subjects generally assigned lower values to rewards than punishments. Furthermore, according to the model (2), AG had significantly lower degree of aversion to punishments. Likewise, according to the model (3), AG expected punishments from incorrect responses less than CG. Our results, showed impaired salience attribution, difficulties in suppression of prepotent responses and heightened perseveration. These suggest that ”punishment” secondary to an incorrect response might not yield enough salience to evoke attention and/or working memory in alcohol addiction to create the necessary shift in the response and this might underpin the perseveration in reward-based learning.

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