Attractor models of working memory and their modulation by reward

  • Authors:
  • Justin R. Chumbley;Raymond J. Dolan;Karl J. Friston

  • Affiliations:
  • Institute of Neurology, UCL, The Wellcome Trust Centre for Neuroimaging, 12 Queen Square, WC1N 3BG, London, UK;Institute of Neurology, UCL, The Wellcome Trust Centre for Neuroimaging, 12 Queen Square, WC1N 3BG, London, UK;Institute of Neurology, UCL, The Wellcome Trust Centre for Neuroimaging, 12 Queen Square, WC1N 3BG, London, UK

  • Venue:
  • Biological Cybernetics
  • Year:
  • 2008

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Abstract

This work reports an empirical examination of two key issues in theoretical neuroscience: distractibility in the context of working memory (WM) and its reward dependence. While these issues have been examined fruitfully in isolation (e.g. Macoveanu et al. in Biol Cybern 96(4): 407–19, 2007), we address them here in tandem, with a focus on how distractibility and reward interact. In particular, we parameterise an observation model that embodies the nonlinear form of such interactions, as described in a recent neuronal network model (Gruber et al. in J Comput Neurosci 20:153–166, 2006). We observe that memory for a target stimulus can be corrupted by distracters in the delay period. Interestingly, in contrast to our theoretical predictions, this corruption was only partial. Distracters do not simply overwrite target; rather, a compromise is reached between target and distracter. Finally, we observed a trend towards a reduced distractibility under conditions of high reward. We discuss the implications of these findings for theoretical formulations of basal and dopamine (DA)-modulated neural bump- attractor networks of working memory.