title: Morphological elucidation of basal ganglia circuits contributing reward prediction.
abstract: Electrophysiological studies in monkeys have shown that dopaminergic neurons respond to the reward prediction error. In addition, striatal neurons alter their responsiveness to cortical or thalamic inputs in response to the dopamine signal, via the mechanism of dopamine-regulated synaptic plasticity. These findings have led to the hypothesis that the striatum exhibits synaptic plasticity under the influence of the reward prediction error and conduct reinforcement learning throughout the basal ganglia circuits. The reinforcement learning model is useful; however, the mechanism by which such a process emerges in the basal ganglia needs to be anatomically explained. The actor-critic model has been previously proposed and extended by the existence of role sharing within the striatum, focusing on the striosome/matrix compartments. However, this hypothesis has been difficult to confirm morphologically, partly because of the complex structure of the striosome/matrix compartments. Here, we review recent morphological studies that elucidate the input/output organization of the striatal compartments.
authors.affiliation: Laboratory of Neural Circuitry, Department of Systems Neuroscience, Graduate School of Brain Science, Doshisha University Kyoto, Japan ; Core Research for Evolutional Science and Technology, Japan Science and Technology Agency Tokyo, Japan.
authors.forename: Fumino
authors.initials: F
authors.lastname: Fujiyama
authors.affiliation: Laboratory of Neural Circuitry, Department of Systems Neuroscience, Graduate School of Brain Science, Doshisha University Kyoto, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Takahashi
authors.affiliation: Laboratory of Neural Circuitry, Department of Systems Neuroscience, Graduate School of Brain Science, Doshisha University Kyoto, Japan.
authors.forename: Fuyuki
authors.initials: F
authors.lastname: Karube
keywords: actor-critic; cortex; dopamine; reinforcement learning; striatum; striosome/matrix compartments; thalamus