Decision making in the Balloon Analogue Risk Task (BART): anterior cingulate cortex signals loss aversion but not the infrequency of risky choices

Abstract

The inferior frontal gyrus/anterior insula (IFG/AI) and anterior cingulate cortex (ACC) are key regions involved in risk appraisal during decision making, but accounts of how these regions contribute to decision making under risk remain contested. To help clarify the roles of these and other related regions, we used a modified version of the Balloon Analogue Risk Task (Lejuez et al., Journal of Experimental Psychology: Applied, 8, 75-84, 2002) to distinguish between decision-making and feedback-related processes when participants decided to pursue a gain as the probability of loss increased parametrically. Specifically, we set out to test whether the ACC and IFG/AI regions correspond to loss aversion at the time of decision making in a way that is not confounded with either reward-seeking or infrequency effects. When participants chose to discontinue inflating the balloon (win option), we observed greater ACC and mainly bilateral IFG/AI activity at the time of decision as the probability of explosion increased, consistent with increased loss aversion but inconsistent with an infrequency effect. In contrast, we found robust vmPFC activity when participants chose to continue inflating the balloon (risky option), consistent with reward seeking. However, in the cingulate and in mainly bilateral IFG regions, blood-oxygenation-level-dependent activation decreased when participants chose to inflate the balloon as the probability of explosion increased, findings that are consistent with a reduced loss aversion signal. Our results highlight the existence of distinct reward-seeking and loss-averse signals during decision making, as well as the importance of distinguishing between decision and feedback signals.

Figure 1

Competing hypotheses regarding decision-making signals. Parametric modulators were used to identify brain regions where activation was positively or negatively correlated with the probability of explosion. We focused on two main parametrically-modulated regressors (indicated by the label *P(explode). In all panels, the vertical axis represents a neural ‘risk’ signal,’ i.e. an MR signal effect in which activation increases as inflation (ChooseInflate*P(explode)) is chosen with increasing probability of explosion. The horizontal axis represents the pre-determined probabilities of balloon explosion. A, B, C These three panels depict competing hypotheses about the role of the inferior frontal gyrus/anterior insula (IFG/AI) and anterior cingulate cortex (ACC) in choice behavior. The bold line represents the selection of the risky option (ChooseInflate*P(explode)), in which the participant chooses to inflate the balloon. The dotted line represents the selection of the safe option (ChooseWin*P(explode)), in which the participants chooses to stop inflating the balloon and take the sure win. If the IFG/AI activity reflects loss-aversion signals as we hypothesize, then the correlation between the probability of explosion and neural risk signal should look like (A), showing a negative relationship for the risky option and positive relationship for the safe option. Alternatively, if the IFG/AI generates reward-seeking signals, then the correlation for the risky option should be positive (B); and if ACC signals infrequency effects then the correlation for the sure option should be negative (C).

Figure 2

Overview of Balloon Analogue Risk Task (BART) procedure and presentation.

Figure 3

Decision phase parametric modulators. We focused on two main parametrically-modulated regressors (indicated by the label *P(explode). Panels (A) and (B) show ROI analyses of brain regions showing a negative correlation between the neural risk effect and the increasing probability of explosion during the decision phase. (A) Shown in red is a sagittal slice of ACC (peak voxel: MNI 6, 26, 24) and (B) shown in yellow and blue is a transverse slice of bilateral IFG/AI (peak voxel: MNI −44, 16, −8 and 48, 20, −6) for the ChooseInflate*P(explode) (risky option) regressor. Panels (C) and (D) shows ROI analysis of brain regions showing a positive correlation between the neural risk effect and the increasing probability of explosion during the decision phase. (C) Shown in green is a sagittal slice of left vmPFC (peak voxel: MNI −12, 36, −18) for the ChooseInflate*P(explode) (risky option) regressor. (D) Shown in violet and cyan is a transverse slice of bilateral IFG/INS for the ChooseWin*P(explode) (sure option) regressor.