title: Reward value-based gain control: divisive normalization in parietal cortex.
abstract: The representation of value is a critical component of decision making. Rational choice theory assumes that options are assigned absolute values, independent of the value or existence of other alternatives. However, context-dependent choice behavior in both animals and humans violates this assumption, suggesting that biological decision processes rely on comparative evaluation. Here we show that neurons in the monkey lateral intraparietal cortex encode a relative form of saccadic value, explicitly dependent on the values of the other available alternatives. Analogous to extra-classical receptive field effects in visual cortex, this relative representation incorporates target values outside the response field and is observed in both stimulus-driven activity and baseline firing rates. This context-dependent modulation is precisely described by divisive normalization, indicating that this standard form of sensory gain control may be a general mechanism of cortical computation. Such normalization in decision circuits effectively implements an adaptive gain control for value coding and provides a possible mechanistic basis for behavioral context-dependent violations of rationality.
authors.affiliation: Center for Neural Science and Center for Neuroeconomics, New York University, New York, New York 10003, USA. klouie@cns.nyu.edu
authors.forename: Kenway
authors.initials: K
authors.lastname: Louie
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Grattan
authors.forename: Paul W
authors.initials: PW
authors.lastname: Glimcher
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D016009:Chi-Square Distribution; D002755:Choice Behavior / Q000502:physiology*; D008253:Macaca mulatta; D008297:Male; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology*; D010296:Parietal Lobe / Q000166:cytology / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011237:Predictive Value of Tests; D012016:Reference Values; D012201:Reward; D013997:Time Factors