title: Inactivation of the putamen selectively impairs reward history-based action selection.
abstract: Behavioral decisions and actions are directed to achieve specific goals and to obtain rewards and escape punishments. Previous studies involving the recording of neuronal activity suggest the involvement of the cerebral cortex, basal ganglia, and midbrain dopamine system in these processes. The value signal of the action options is represented in the striatum, updated by reward prediction errors, and used for selecting higher-value actions. However, it remains unclear whether dysfunction of the striatum leads to impairment of value-based action selection. The present study examined the effect of inactivation of the putamen via local injection of the GABA(A) receptor agonist muscimol in monkeys engaged in a manual reward-based multi-step choice task. The monkeys first searched a reward target from three alternatives, based on the previous one or two choices and their outcomes, and obtained a large reward; they then earned an additional reward by choosing the last rewarded target. Inactivation of the putamen impaired the ability of monkeys to make optimal choices during third trial in which they were required to choose a target different from those selected in the two previous trials by updating the values of the three options. The monkeys normally changed options if the last choice resulted in small reward (lose-shift) and stayed with the last choice if it resulted in large reward (win-stay). Task start time and movement time during individual trials became longer after putamen inactivation. But monkeys could control the motivation level depending on the reward value of individual trial types before and after putamen inactivation. These results support a view that the putamen is involved selectively and critically in neuronal circuits for reward history-based action selection.
authors.affiliation: Department of Neurophysiology, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. muranishi.manabu@jp.panasonic.com
authors.forename: Manabu
authors.initials: M
authors.lastname: Muranishi
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Inokawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamada
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Ueda
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Matsumoto
authors.forename: Masanori
authors.initials: M
authors.lastname: Nakagawa
authors.forename: Minoru
authors.initials: M
authors.lastname: Kimura
mesh_terms: D000818:Animals; D003657:Decision Making / Q000502:physiology*; D005260:Female; D006040:Goals; D008251:Macaca; D009118:Muscimol; D009474:Neurons / Q000502:physiology*; D011699:Putamen / Q000503:physiopathology*; D012201:Reward
chemical_list: D009118:Muscimol