Decision-making studies across different domains suggest that decisions can arise from multiple, parallel systems in the brain: a flexible system utilizing action-outcome expectancies and a more rigid system based on situation-action associations. The hippocampus, ventral striatum, and dorsal striatum make unique contributions to each system, but how information processing in each of these structures supports these systems is unknown. Recent work has shown covert representations of future paths in hippocampus and of future rewards in ventral striatum. We developed analyses in order to use a comparative methodology and apply the same analyses to all three structures. Covert representations of future paths and reward were both absent from the dorsal striatum. In contrast, dorsal striatum slowly developed situation representations that selectively represented action-rich parts of the task. This triple dissociation suggests that the different roles these structures play are due to differences in information-processing mechanisms.
Bibliographical noteFunding Information:
We thank Anoopum Gupta, Jadin Jackson, and Paul Schrater for discussion, and David Crowe and Geoffrey Schoenbaum for comments on a previous version of the manuscript. Supported by NIH grants MH068029, MH080318, T32HD007151 (Center for Cognitive Sciences, University of Minnesota), IGERT training grant 9870633, graduate student NSF fellowships, Dissertation Fellowships, and the Land Grant Professorship program at the University of Minnesota. This work has been published in abstract form (Frontiers in Systems Neuroscience, conference abstract: CoSyNe 2009); we are grateful to the conference participants for their suggestions.