Prediction of economic choice by primate amygdala neurons

Abstract

The amygdala is a key structure of the brain's reward system. Existing theories view its role in decision-making as restricted to an early valuation stage that provides input to decision mechanisms in downstream brain structures. However, the extent to which the amygdala itself codes information about economic choices is unclear. Here, we report that individual neurons in the primate amygdala predict behavioral choices in an economic decision task. We recorded the activity of amygdala neurons while monkeys chose between saving liquid reward with interest and spending the accumulated reward. In addition to known value-related responses, we found that activity in a group of amygdala neurons predicted the monkeys' upcoming save-spend choices with an average accuracy of 78%. This choicepredictive activity occurred early in trials, even before information about specific actions associated with save-spend choices was available. For a substantial number of neurons, choice-differential activity was specific for free, internally generated economic choices and not observed in a control task involving forced imperative choices. A subgroup of choice-predictive neurons did not show relationships to value, movement direction, or visual stimulus features. Choicepredictive activity in some amygdala neurons was preceded by transient periods of value coding, suggesting value-to-choice transitions and resembling decision processes in other brain systems. These findings suggest that the amygdala might play an active role in economic decisions. Current views of amygdala function should be extended to incorporate a role in decision-making beyond valuation.neurophysiology | abstract representation | subjective value | emotion

A neuro-computational model of economic decisions

“…Furthermore, chosen value cells have no known correspondent in perceptual decision tasks. In contrast, chosen value signals have been observed in numerous studies of value-based decisions and in multiple brain regions (Amemori and Graybiel 2012;Cai et al 2011;Padoa-Schioppa 2012, 2014;Grabenhorst et al 2012;Lau and Glimcher 2008;Lee et al 2012;Padoa-Schioppa and Assad 2006;Roesch et al 2009;Strait et al 2014;Sul et al 2010;Wunderlich et al 2010). While it is clear that chosen value signals could inform a variety of mental functions including associative learning, visual attention, emotion, and others, the possible contributions of chosen value signals to economic decisions have remained mysterious.…”

Neuronal Reward and Decision Signals: From Theories to Data

“…Abstract decision signals occur also in specific neurons in the amygdala that show graded reward value coding early during the trial and transition to later binary abstract decision coding (FIGURE 42B) (188). The decision signal from 1-50 pooled neurons predicts the upcoming choice correctly in 75-90% of trials, respectively, and remained predictive even with identical reward between the two options.…”

“…The activities concern the initial accumulation of evidence, implemented by gradually increasing ramping activity in perceptual decisions (FIGURES 35, top, and 36, A AND B), and the subsequent valuation of the options. The central competitive process and its outputs (FIGURES 35, middle and bottom, and 36C) are reflected in distinct neuronal activities coding the input decision variables of object value (405) and action value (500), the abstract decision output (188), and the chosen value (405), chosen object (38), and chosen action (543). Updating of decision variables via prediction errors occurs globally via dopamine neurons and locally through specific groups of non-dopamine reward neurons (FIGURE 35, right).…”

Amygdala signals subjective appetitiveness and aversiveness of mixed gambles

“…The classical view that the amygdala are mainly geared to negative events has been recently challenged by neuroimaging studies showing that the amygdala computes both negative and positive stimulus values during value-based decisionmaking (Baxter & Murray, 2002;Bermudez, Gobel, & Schultz, 2012;Grabenhorst, Hernadi, & Schultz, 2012;Jenison, Rangel, Oya, Kawasaki, & Howard, 2011). The "bivalent" coding of value in the amygdala, which is not specific to negativity or positivity of a stimulus, per se, suggests that the amygdala may track other properties of these value stimuli such as task relevance, the impact or consequence of a choice, or the biological salience of a stimulus.…”