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Ventral pallidal neurons code incentive motivation: amplification by mesolimbic sensitization and amphetamine
Author(s) -
Tindell Amy J.,
Berridge Kent C.,
Zhang Jun,
Peciña Susana,
Aldridge J. Wayne
Publication year - 2005
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2005.04411.x
Subject(s) - incentive salience , neuroscience , psychology , ventral pallidum , amphetamine , sensitization , classical conditioning , stimulus (psychology) , neural coding , addiction , conditioning , dopamine , basal ganglia , globus pallidus , central nervous system , cognitive psychology , statistics , mathematics
Neurons in ventral pallidum fire to reward and its predictive cues. We tested mesolimbic activation effects on neural reward coding. Rats learned that a Pavlovian conditioned stimulus (CS+1 tone) predicted a second conditioned stimulus (CS+2 feeder click) followed by an unconditioned stimulus (UCS sucrose reward). Some rats were sensitized to amphetamine after training. Electrophysiological activity of ventral pallidal neurons to stimuli was later recorded under the influence of vehicle or acute amphetamine injection. Both sensitization and acute amphetamine increased ventral pallidum firing at CS+2 (population code and rate code). There were no changes at CS+1 and minimal changes to UCS. With a new ‘ Profile Analysis ’, we show that mesolimbic activation by sensitization/amphetamine incrementally shifted neuronal firing profiles away from prediction signal coding (maximal at CS+1) and toward incentive coding (maximal at CS+2), without changing hedonic impact coding (maximal at UCS). This pattern suggests mesolimbic activation specifically amplifies a motivational transform of CS+ predictive information into incentive salience coded by ventral pallidal neurons. Our results support incentive‐sensitization predictions and suggest why cues temporally proximal to drug presentation may precipitate cue‐triggered relapse in human addicts.