title: Lesions of dorsal striatum eliminate lose-switch responding but not mixed-response strategies in rats.
abstract: We used focal brain lesions in rats to examine how dorsomedial (DMS) and dorsolateral (DLS) regions of the striatum differently contribute to response adaptation driven by the delivery or omission of rewards. Rats performed a binary choice task under two modes: one in which responses were rewarded on half of the trials regardless of choice; and another 'competitive' one in which only unpredictable choices were rewarded. In both modes, control animals were more likely to use a predictable lose-switch strategy than animals with lesions of either DMS or DLS. Animals with lesions of DMS presumably relied more on DLS for behavioural control, and generated repetitive responses in the first mode. These animals then shifted to a random response strategy in the competitive mode, thereby performing better than controls or animals with DLS lesions. Analysis using computational models of reinforcement learning indicated that animals with striatal lesions, particularly of the DLS, had blunted reward sensitivity and less stochasticity in the choice mechanism. These results provide further evidence that the rodent DLS is involved in rapid response adaptation that is more sophisticated than that embodied by the classic notion of habit formation driven by gradual stimulus-response learning.
authors.affiliation: Department of Neuroscience, Canadian Centre for Behavioural Neuroscience, University of Lethbridge, 4401 University Dr. W., T1K 3M4, Lethbridge, AB, Canada.
authors.forename: Ivan
authors.initials: I
authors.lastname: Skelin
authors.forename: Rhys
authors.initials: R
authors.lastname: Hakstol
authors.forename: Jenn
authors.initials: J
authors.lastname: VanOyen
authors.forename: Dominic
authors.initials: D
authors.lastname: Mudiayi
authors.forename: Leonardo A
authors.initials: LA
authors.lastname: Molina
authors.forename: Victoria
authors.initials: V
authors.lastname: Holec
authors.forename: Nancy S
authors.initials: NS
authors.lastname: Hong
authors.forename: David R
authors.initials: DR
authors.lastname: Euston
authors.forename: Robert J
authors.initials: RJ
authors.lastname: McDonald
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Gruber
mesh_terms: D000223:Adaptation, Psychological / Q000502:physiology; D000818:Animals; D002755:Choice Behavior / Q000502:physiology*; D003198:Computer Simulation; D003342:Corpus Striatum / Q000502:physiology* / Q000503:physiopathology; D056344:Executive Function / Q000502:physiology*; D007858:Learning / Q000502:physiology; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008959:Models, Neurological; D009483:Neuropsychological Tests; D020318:Rats, Long-Evans; D012054:Reinforcement, Psychology; D012201:Reward; D013269:Stochastic Processes; D013647:Task Performance and Analysis; D035501:Uncertainty
keywords: decision-making; dorsolateral striatum; dorsomedial striatum; matching pennies; win-stay lose-switch