title: [Value representation in the striatum and prefrontal cortex].
abstract: To survive under changing circumstances, we have to make appropriate decisions on our behavior. For this purpose, the brain should recognize reward information from objects under a given circumstances. Recent experimental and theoretical studies have suggested that primates, including human beings, have at least 2 brain processes that calculate the reward value of objects. One is the process coding a specific reward value of a stimulus or response, depending on direct experience (e.g., classical conditioning and TD learning). The other enables us to predict reward based on the internal model of given circumstances without direct experience (e.g., categorization and inference). To clarify the neuronal correlates of the multiple processes on reward prediction, we have conducted 4 experiments: (1) single-unit recording from the caudate and lateral prefrontal cortex of a monkey, while it performed a memory-guided saccade task with asymmetric reward schedule; (2) human fMRI imaging during random-dot discrimination with asymmetric reward condition; (3) single-unit recording from the monkey dopamine neuron in the random-dot discrimination task with asymmetric reward schedule; and (4) simultaneous single-unit recording from the striatum and lateral prefrontal cortex of monkeys performing a reward inference task. Results suggest that the nigro striatal network and the prefrontal network have different functional roles for reward prediction (value generation). The former applies the model-free method (temporal-difference learning), while the latter uses the model-based method (category-based learning).
authors.affiliation: Brain Science Research Center, Tamagawa University, Tokyo, Japan.
authors.forename: Masamichi
authors.initials: M
authors.lastname: Sakagami
authors.forename: Manami
authors.initials: M
authors.lastname: Yamamoto
mesh_terms: D000818:Animals; D001931:Brain Mapping; D003342:Corpus Striatum / Q000502:physiology*; D003657:Decision Making / Q000502:physiology*; D059290:Dopaminergic Neurons / Q000502:physiology*; D006801:Humans; D017397:Prefrontal Cortex / Q000502:physiology*; D012201:Reward