In conditional discriminative choice learning, one learns the relations between discriminative/cue stimuli, associated choices, and their outcomes. When each correct cue-choice occurrence is followed by a cue-unique trial outcome (differential outcomes, DO, procedure), learning is faster and more accurate than when all correct cue-choice occurrences are followed by a common outcome (CO procedure)-differential outcomes effect (DOE). Superior DO performance is theorized to be mediated by the additional learning of cue-unique outcome expectations that "enrich" the prospective code available over the delay between cue and choice. We anticipated that such learned expectations comprise representations of expected outcomes. Here, we conducted an event-related functional MR imaging (fMRI) analysis of healthy adults who trained concurrently in two difficult but similar perceptual discrimination tasks under DO and CO procedures, respectively, and displayed the DOE. Control participants performed related tasks that differentially biased them towards delay-period retrospection versus prospection. Indeed, when differential outcomes were sensory-perceptual events (visual vs. auditory), delay-period expectations were experienced as sensory-specific imagery of the respectively expected outcome content, generated by sensory-specific cortices. Visual-specific imagery additionally activated stimulus-specific representations in prefrontal, lateral and medial frontal, fusiform and cerebellar regions, whereas auditory-specific imagery recruited claustrum/insula. Posterior parietal cortex (PPC), BA 39, was non-modality specific in mediating delay-period cue-unique outcome expectations. Greater hippocampal involvement in retrospection than prospection contrasted against the PPC's role in prospection. Time course analyses of hippocampal versus PPC responses suggest the DOE derives from an earlier transition from retrospection to prospection, which taps into long-term associative memory-more enduring.
|Original language||English (US)|
|Number of pages||17|
|State||Published - Apr 10 2009|
Bibliographical noteFunding Information:
This paper is based on L.W.M.'s doctoral dissertation. The research was supported by the Sigma Xi Grants-In-Aid of Research, APAGS Scott Mesh Honorary Scholarship for Research in Psychology, APF/COGDOP Graduate Research Scholarship in Psychology, and APA Dissertation Research Award, made to L.W.M.; L.W.M. was supported by the Overseas Graduate Scholarship, Nanyang Technological Univ., Singapore; the 3T scanner at the Center for Magnetic Resonance Research, Univ. of Minnesota, was supported by the MIND Institute and BTRR P41 008079; the Brain Voyager computing and MR simulator facilities were supported by the Center for Cognitive Sciences, Univ. of Minnesota. We thank Dr. Wilma Koutstaal for her invaluable comments. L.W.M. is now at Nanyang Technological University, Singapore; O.V.L. is now at Université de Montréal, Canada.
- Angular gyrus
- Differential outcomes
- Long-term memory
- Posterior parietal
- Prospective processing
- Retrospective processing
- Working memory