Saleem M Nicola1. 1. Ernest Gallo Clinic and Research Center, University of California, San Francisco, 5858 Horton St., Ste. 200, Emeryville, CA 94608, USA. nicola@phy.ucsf.edu
Abstract
BACKGROUND: The nucleus accumbens is the ventral extent of the striatum, the main input nucleus of the basal ganglia. Recent hypotheses propose that the accumbens and its dopamine projection from the midbrain contribute to appetitive behaviors required to obtain reward. However, the specific nature of this contribution is unclear. In contrast, significant advances have been made in understanding the role of the dorsal striatum in action selection and decision making. OBJECTIVE: In order to develop a hypothesis of the role of nucleus accumbens dopamine in action selection, the physiology and behavioral pharmacology of the nucleus accumbens are compared to those of the dorsal striatum. HYPOTHESES: Three hypotheses concerning the role of dopamine in these structures are proposed: (1) that dopamine release in the dorsal striatum serves to facilitate the ability to respond appropriately to temporally predictable stimuli (that is, stimuli that are so predictable that animals engage in anticipatory behavior just prior to the stimulus); (2) that dopamine in the nucleus accumbens facilitates the ability to respond to temporally unpredictable stimuli (which require interruption of ongoing behavior); and (3) that accumbens neurons participate in action selection in response to such stimuli by virtue of their direct (monosynaptic inhibitory) and indirect (polysynaptic excitatory) projections to basal ganglia output nuclei.
BACKGROUND: The nucleus accumbens is the ventral extent of the striatum, the main input nucleus of the basal ganglia. Recent hypotheses propose that the accumbens and its dopamine projection from the midbrain contribute to appetitive behaviors required to obtain reward. However, the specific nature of this contribution is unclear. In contrast, significant advances have been made in understanding the role of the dorsal striatum in action selection and decision making. OBJECTIVE: In order to develop a hypothesis of the role of nucleus accumbens dopamine in action selection, the physiology and behavioral pharmacology of the nucleus accumbens are compared to those of the dorsal striatum. HYPOTHESES: Three hypotheses concerning the role of dopamine in these structures are proposed: (1) that dopamine release in the dorsal striatum serves to facilitate the ability to respond appropriately to temporally predictable stimuli (that is, stimuli that are so predictable that animals engage in anticipatory behavior just prior to the stimulus); (2) that dopamine in the nucleus accumbens facilitates the ability to respond to temporally unpredictable stimuli (which require interruption of ongoing behavior); and (3) that accumbens neurons participate in action selection in response to such stimuli by virtue of their direct (monosynaptic inhibitory) and indirect (polysynaptic excitatory) projections to basal ganglia output nuclei.
Authors: Jun Wang; Sebastien Carnicella; Somayeh Ahmadiantehrani; Dao-Yao He; Segev Barak; Viktor Kharazia; Sami Ben Hamida; Agustin Zapata; Toni S Shippenberg; Dorit Ron Journal: J Neurosci Date: 2010-10-27 Impact factor: 6.167