title: Neural mechanisms of the nucleus accumbens circuit in reward and aversive learning.
abstract: The basal ganglia are key neural substrates not only for motor function, but also cognitive functions including reward and aversive learning. Critical for these processes are the functional role played by two projection neurons within nucleus accumbens (NAc); the D1- and D2-expressing neurons. Recently, we have developed a novel reversible neurotransmission blocking technique that specifically blocks neurotransmission from NAc D1- and D2-expressing neurons, allowing for in vivo analysis. In this review, we outline the functional dissociation of NAc D1- and D2-expressing neurons of the basal ganglia in reward and aversive learning, as well as drug addiction. These studies have revealed the importance of activation of NAc D1 receptors for reward learning and drug addiction, and inactivation of NAc D2 receptors for aversive learning and flexibility. Based on these findings, we propose a neural mechanism, in which dopamine neurons in the ventral tegmental area that send inputs to the NAc work as a switch between D1- and D2-expressing neurons. These basal ganglia neural mechanisms will give us new insights into the pathophysiology of neuropsychiatric diseases.
authors.affiliation: Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan. Electronic address: hikida@tk.med.kyoto-u.ac.jp.
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Hikida
authors.affiliation: Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.
authors.forename: Makiko
authors.initials: M
authors.lastname: Morita
authors.affiliation: Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.
authors.forename: Tom
authors.initials: T
authors.lastname: Macpherson
mesh_terms: D000818:Animals; D001362:Avoidance Learning; D006801:Humans; D009474:Neurons / Q000378:metabolism; D009714:Nucleus Accumbens / Q000502:physiology*; D017447:Receptors, Dopamine D1 / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000378:metabolism; D012201:Reward; D019966:Substance-Related Disorders / Q000378:metabolism / Q000503:physiopathology
chemical_list: D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2
keywords: Basal ganglia; Dopamine; Dopamine receptor; Drug addiction; Plasticity; Reversible neurotransmission blocking