title: Basal ganglia circuit loops, dopamine and motivation: A review and enquiry.
abstract: Dopamine neurons located in the midbrain play a role in motivation that regulates approach behavior (approach motivation). In addition, activation and inactivation of dopamine neurons regulate mood and induce reward and aversion, respectively. Accumulating evidence suggests that such motivational role of dopamine neurons is not limited to those located in the ventral tegmental area, but also in the substantia nigra. The present paper reviews previous rodent work concerning dopamine's role in approach motivation and the connectivity of dopamine neurons, and proposes two working models: One concerns the relationship between extracellular dopamine concentration and approach motivation. High, moderate and low concentrations of extracellular dopamine induce euphoric, seeking and aversive states, respectively. The other concerns circuit loops involving the cerebral cortex, basal ganglia, thalamus, epithalamus, and midbrain through which dopaminergic activity alters approach motivation. These models should help to generate hypothesis-driven research and provide insights for understanding altered states associated with drugs of abuse and affective disorders.
authors.affiliation: Behavioral Neuroscience Branch, National Institute on Drug Abuse, National Institutes of Health, 251 Bayview Blvd., Suite 200, Baltimore, MD 21224, USA. Electronic address: sikemoto@mail.nih.gov.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ikemoto
authors.affiliation: Behavioral Neuroscience Branch, National Institute on Drug Abuse, National Institutes of Health, 251 Bayview Blvd., Suite 200, Baltimore, MD 21224, USA.
authors.forename: Chen
authors.initials: C
authors.lastname: Yang
authors.affiliation: Behavioral Neuroscience Branch, National Institute on Drug Abuse, National Institutes of Health, 251 Bayview Blvd., Suite 200, Baltimore, MD 21224, USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Tan
mesh_terms: D000818:Animals; D001479:Basal Ganglia / Q000502:physiology*; D059290:Dopaminergic Neurons / Q000502:physiology*; D009042:Motivation / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D012201:Reward
keywords: Depression; Dorsal striatum; Euphoria; Global pallidus; Mania; Mediodorsal thalamic nucleus