Activity in human reward-sensitive brain areas is strongly context dependent

Abstract

Functional neuroimaging research in humans has identified a number of brain areas that are activated by the delivery of primary and secondary reinforcers. The present study investigated how activity in these reward-sensitive regions is modulated by the context in which rewards and punishments are experienced. Fourteen healthy volunteers were scanned during the performance of a simple monetary gambling task that involved a bwinQ condition (in which the possible outcomes were a large monetary gain, a small gain, or no gain of money) and a bloseQ condition (in which the possible outcomes were a large monetary loss, a small loss, or no loss of money). We observed reward-sensitive activity in a number of brain areas previously implicated in reward processing, including the striatum, prefrontal cortex, posterior cingulate, and inferior parietal lobule. Critically, activity in these reward-sensitive areas was highly sensitive to the range of possible outcomes from which an outcome was selected. In particular, these regions were activated to a comparable degree by the best outcomes in each condition-a large gain in the win condition and no loss of money in the lose condition-despite the large difference in the objective value of these outcomes. In addition, some rewardsensitive brain areas showed a binary instead of graded sensitivity to the magnitude of the outcomes from each distribution. These results provide important evidence regarding the way in which the brain scales the motivational value of events by the context in which these events occur. D

Valence and salience contribute to nucleus accumbens activation

“…Accordingly, replications of the MID task have found the difference for large but not small incentives (i.e., $5.00, but not $1.00). Alternatively, this study's novel mixture of certain and uncertain trials may have induced a framing effect in which participants considered both the chance to obtain gains and the chance to avoid losses in uncertain trials to be rewarding relative to certain losses (Ikemoto and Panksepp, 1999;Nieuwenhuis et al, 2005). Consistent with this possibility, participants' positivity ratings were more negative for certain-loss than uncertainloss trials and distinguished between gain and loss better in certain than uncertain trials.…”

Does the brain calculate value?

“…Neurophysiological recordings in monkeys and humans have shown evidence that comparative reward coding in neural substrates (e.g., via dopamine projections to the striatum and the orbitofrontal cortex) is strongly implicated in simple choice behaviour [71][72][73] (see Figure II).…”

“…(a) The macaque orbitofrontal cortex responds to a reward only when it is the preferred outcome in a pair [73]. (b) fMRI BOLD signals from the human ventral striatum exhibit similar response patterns, i.e., the activity is based only on the ordinal ranking of a monetary outcome in the present context (highest activity when the best option and lowest activity for the worst option), irrespectively of whether outcomes are losses or gains [71]. …”

The Neurobiology of Reference-Dependent Value Computation

“…We report results in a priori regions of interest (striatum, insula, and orbital and medial prefrontal cortex) motivated by the fact that these are regions typically identified in neuroimaging studies financial gain evaluation (O'Doherty, 2004;Nieuwenhuis et al, 2005;Seymour et al, 2007;Tom et al, 2007) at p Ͻ 0.001 uncorrected for multiple comparisons (Z Ͻ 3.1) (unless otherwise stated) and/or at p Ͻ 0.05 small volume correction for multiple comparison (SVC) using a 8 mm sphere centered on the peak activity for the a priori regions of interest as reported by previous studies. Activations in other regions are reported if they survive whole-brain correction for multiple comparisons at p Ͻ 0.05.…”