title: A test of the reward-value hypothesis.
abstract: Rats retain source memory (memory for the origin of information) over a retention interval of at least 1 week, whereas their spatial working memory (radial maze locations) decays within approximately 1 day. We have argued that different forgetting functions dissociate memory systems. However, the two tasks, in our previous work, used different reward values. The source memory task used multiple pellets of a preferred food flavor (chocolate), whereas the spatial working memory task provided access to a single pellet of standard chow-flavored food at each location. Thus, according to the reward-value hypothesis, enhanced performance in the source memory task stems from enhanced encoding/memory of a preferred reward. We tested the reward-value hypothesis by using a standard 8-arm radial maze task to compare spatial working memory accuracy of rats rewarded with either multiple chocolate or chow pellets at each location using a between-subjects design. The reward-value hypothesis predicts superior accuracy for high-valued rewards. We documented equivalent spatial memory accuracy for high- and low-value rewards. Importantly, a 24-h retention interval produced equivalent spatial working memory accuracy for both flavors. These data are inconsistent with the reward-value hypothesis and suggest that reward value does not explain our earlier findings that source memory survives unusually long retention intervals.
authors.affiliation: Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405-7007, USA.
authors.forename: Alexandra E
authors.initials: AE
authors.lastname: Smith
authors.affiliation: Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405-7007, USA.
authors.forename: Stefan J
authors.initials: SJ
authors.lastname: Dalecki
authors.affiliation: Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405-7007, USA. jcrystal@indiana.edu.
authors.forename: Jonathon D
authors.initials: JD
authors.lastname: Crystal
mesh_terms: D000818:Animals; D018782:Maze Learning; D008570:Memory, Short-Term; D051381:Rats; D012201:Reward; D065852:Spatial Memory
keywords: Episodic memory; Rats; Reward value; Source memory; Spatial memory