Presentation Details
| Online integration of associatively activated odor memories in the human brain Xiaolin Qiao, Lauren A.Wolters, Liam P.McMahon, Jared G.Newell, James D.Howard. Department of Psychology, Brandeis University, Waltham, MA, USA |
Abstract
Adaptive decision making requires both directly observable information and inferences made on past experience with other related stimuli and situations. One potential inference mechanism is known as online integration, in which latent representations are associatively linked to relevant stimuli prospectively, prior to the point of a later decision. Recent experiments in humans and non-human animals point to medial temporal lobe and ventral prefrontal cortex as key substrates supporting inference-based decision making. However, whether these regions specifically support online integration in humans is not known. We recently implemented a representation-mediated learning task (RML) in conjunction with fMRI (N=30) to test this hypothesis. In this task, participants first learned associations between visual symbols and two distinct appetitive food odors. We then acquired pleasantness ratings for symbols and odors before and after one of the symbols was paired with an aversive sound. Behaviorally, participants showed a selective decrease in the pleasantness rating for the odor previously paired with the aversively conditioned symbol. Using multivoxel pattern analysis, we first identified brain activity patterns reflecting expected odor identity from the appetitive learning phase in orbitofrontal cortex (OFC) and parahippocampal gyrus (PHG). Critically, we found that these odor identity expectations were reactivated in the OFC and PHG when the visual cue was presented during aversive conditioning. These preliminary findings provide a potential neural mechanism by which previously learned odor associations are prospectively linked to the aversive sound, despite the odors never being directly paired with the sound.
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