title: Reward value-contingent changes of visual responses in the primate caudate tail associated with a visuomotor skill.
abstract: A goal-directed action aiming at an incentive outcome, if repeated, becomes a skill that may be initiated automatically. We now report that the tail of the caudate nucleus (CDt) may serve to control a visuomotor skill. Monkeys looked at many fractal objects, half of which were always associated with a large reward (high-valued objects) and the other half with a small reward (low-valued objects). After several daily sessions, they developed a gaze bias, looking at high-valued objects even when no reward was associated. CDt neurons developed a response bias, typically showing stronger responses to high-valued objects. In contrast, their responses showed no change when object values were reversed frequently, although monkeys showed a strong gaze bias, looking at high-valued objects in a goal-directed manner. The biased activity of CDt neurons may be transmitted to the oculomotor region so that animals can choose high-valued objects automatically based on stable reward experiences.
authors.affiliation: Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA. yamamoto-s@aist.go.jp
authors.forename: Shinya
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Hyoung F
authors.initials: HF
authors.lastname: Kim
authors.forename: Okihide
authors.initials: O
authors.lastname: Hikosaka
mesh_terms: D000818:Animals; D002421:Caudate Nucleus / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology*; D006040:Goals; D008253:Macaca mulatta; D008297:Male; D010775:Photic Stimulation / Q000379:methods*; D011323:Primates; D011597:Psychomotor Performance / Q000502:physiology*; D011897:Random Allocation; D012201:Reward