Connectionists: Model of Orbitofrontal and Basal Ganglia Contributions to Decision Making

[Michael J Frank]

The following paper is available for download from
http://www.u.arizona.edu/~mfrank/pubs-online.html

Frank, M.J. & Claus, E.D. (in press). Anatomy of a decision:
Striato-orbitofrontal interactions in reinforcement learning, decision
making and reversal. Psychological Review.

Abstract:
We explore the division of labor between the basal ganglia (BG) /
dopamine (DA) system and orbitofrontal cortex (OFC) in reinforcement
learning and decision making. We show that a "primitive" neural
network model of the BG/DA system learns to make decisions based on
their relative likelihood of reinforcement, but that the same model
fails when the magnitude of gains and losses is more relevant than
their frequency of occurence. An augmented model including OFC and
amygdalar interactions with the BG system is more successful at
estimating the true expected value of decisions, and is faster at
learning to switch behavior when decision-outcome contingencies
change. In our combined model, "Go" and "NoGo" BG pathways modulate
the selection of premotor responses based on their probability of
reinforcement, whereas medial and lateral OFC areas exert top-down
control by representing reinforcement magnitudes in working memory.
The model successfully captures patterns of behavior resulting from
OFC damage in decision making, reversal learning, and devaluation
paradigms, and makes additional predictions for the underlying source
of these deficits.

Michael J Frank, PhD
Assistant Professor
Laboratory for Neural Computation and Cognition
University of Arizona
1503 E University Blvd, Bldg#68, Tucson, AZ 85721
mfrank at u.arizona.edu
http://www.u.arizona.edu/~mfrank/