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Computational Intelligence and Neuroscience
Volume 2014 (2014), Article ID 383790, 12 pages
Research Article

A Two-Layered Diffusion Model Traces the Dynamics of Information Processing in the Valuation-and-Choice Circuit of Decision Making

1Department of Medicine, Surgery & Neurosciences, University of Siena, Viale Bracci 2, 53100 Siena, Italy
2Eye-Tracking & Visual Application Lab, University of Siena, Viale Bracci 2, 53100 Siena, Italy
3Department of Social, Political and Cognitive Sciences, University of Siena, Via Roma 56, 53100 Siena, Italy

Received 29 October 2013; Revised 18 July 2014; Accepted 7 August 2014; Published 31 August 2014

Academic Editor: Pablo Varona

Copyright © 2014 Pietro Piu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A circuit of evaluation and selection of the alternatives is considered a reliable model in neurobiology. The prominent contributions of the literature to this topic are reported. In this study, valuation and choice of a decisional process during Two-Alternative Forced-Choice (TAFC) task are represented as a two-layered network of computational cells, where information accrual and processing progress in nonlinear diffusion dynamics. The evolution of the response-to-stimulus map is thus modeled by two linked diffusive modules (2LDM) representing the neuronal populations involved in the valuation-and-decision circuit of decision making. Diffusion models are naturally appropriate for describing accumulation of evidence over the time. This allows the computation of the response times (RTs) in valuation and choice, under the hypothesis of ex-Wald distribution. A nonlinear transfer function integrates the activities of the two layers. The input-output map based on the infomax principle makes the 2LDM consistent with the reinforcement learning approach. Results from simulated likelihood time series indicate that 2LDM may account for the activity-dependent modulatory component of effective connectivity between the neuronal populations. Rhythmic fluctuations of the estimate gain functions in the delta-beta bands also support the compatibility of 2LDM with the neurobiology of DM.