Separating value from choice: delay discounting activity in the lateral intraparietal area.
The mathematical formulations used to study the neurophysiological signals governing choice behavior fall under one of two major theoretical frameworks: "choice probability" or "subjective value." These two formulations represent behavioral quantities closely tied to the decision process, but it is unknown whether one of these variables, or both, dominates the neural mechanisms that mediate choice. Value and choice probability are difficult to distinguish in practice, because higher-valued options are chosen more frequently in free-choice tasks. This distinction is particularly relevant for sensorimotor areas such as parietal cortex, where both value information and motor signals related to choice have been observed. We recorded the activity of neurons in the lateral intraparietal area while monkeys performed an intertemporal choice task for rewards differing in delay to reinforcement. Here we show that the activity of parietal neurons is precisely correlated with the individual-specific discounted value of delayed rewards, with peak subjective value modulation occurring early in task trials. In contrast, late in the decision process these same neurons transition to encode the selected action. When directly compared, the strong delay-related modulation early during decision making is driven by subjective value rather than the monkey's probability of choice. These findings show that in addition to information about gains, parietal cortex also incorporates information about delay into a precise physiological correlate of economic value functions, independent of the probability of choice.
Louie
Kenway
K
Center for Neural Science, New York University, New York, New York 10003, USA. klouie@cns.nyu.edu
Glimcher
Paul W
PW
D000818:Animals; D002755:Choice Behavior / Q000502:physiology*; D008253:Macaca mulatta; D008297:Male; D009474:Neurons / Q000502:physiology; D010296:Parietal Lobe / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D012201:Reward; D013997:Time Factors
Games Econ Behav. 2005 Aug;52(2):213-256
16845435
Neuron. 2008 May 8;58(3):451-63
18466754
J Neurophysiol. 2001 Oct;86(4):1916-36
11600651
Neuron. 2003 Apr 24;38(2):317-27
12718864
Nature. 2006 Sep 7;443(7107):85-8
16936716
Neuron. 2008 Jul 10;59(1):161-72
18614037
Neuron. 2004 Jun 24;42(6):1003-12
15207244
Q J Exp Psychol. 1980 Feb;32(1):3-25
7367577
Nature. 2006 May 11;441(7090):223-6
16633341
J Exp Anal Behav. 1991 Mar;55(2):233-44
2037827
Nature. 2002 Jan 10;415(6868):165-8
11805833
Trends Cogn Sci. 2004 Jun;8(6):261-5
15165551
Neuron. 2004 Oct 14;44(2):365-78
15473973
Nature. 1997 Mar 13;386(6621):167-70
9062187
Ann N Y Acad Sci. 2002 Apr;956:205-15
11960805
Annu Rev Neurosci. 2002;25:189-220
12052908
Nature. 1989 Sep 7;341(6237):52-4
2770878
Nature. 1998 Oct 1;395(6701):500-3
9774105
Nat Neurosci. 2008 Jan;11(1):95-102
18066060
Nat Rev Neurosci. 2005 May;6(5):363-75
15832198
J Neurosci. 2002 Nov 1;22(21):9475-89
12417672
Nat Neurosci. 2005 Feb;8(2):234-41
15657597
Exp Brain Res. 1988;70(1):216-20
3402565
J Appl Physiol. 1966 May;21(3):1068-70
4958032
J Exp Anal Behav. 1995 Nov;64(3):263-76
16812772
J Neurophysiol. 2005 Oct;94(4):2457-71
15958600
Nature. 2007 Jun 28;447(7148):1075-80
17546027
J Neurosci. 2006 Aug 9;26(32):8310-9
16899726
Curr Opin Neurobiol. 2004 Apr;14(2):139-47
15082317
J Neurosci. 1992 Dec;12(12):4745-65
1464765
Annu Rev Neurosci. 2007;30:535-74
17600525
Science. 2004 Jun 18;304(5678):1782-7
15205529
Nature. 1998 Jan 29;391(6666):481-4
9461214
Science. 1997 Mar 14;275(5306):1593-9
9054347
Nature. 1999 Jul 15;400(6741):233-8
10421364