Association of degree of loss aversion and grey matter volume in superior frontal gyrus by voxel-based morphometry

Posterior fronto-medial atrophy reflects decreased loss aversion, but not executive impairment, in alcohol use disorder

Decreased punishment sensitivity in alcohol use disorder (AUD) might reflect a reduction in the typical human tendency to overweigh negative choice outcomes compared with equivalent positive ones, that is, 'loss aversion.' While this hypothesis is supported by previous reports of reduced loss aversion in AUD, it is still unknown whether such decreased sensitivity to prospective losses represents a specific facet of altered decision-making or a secondary effect of executive/working-memory impairments. We addressed this issue by assessing whether lower loss aversion in 22 AUD patients compared with 19 healthy controls is explained by their differential executive or working-memory performance and by investigating its neural basis in terms of grey matter density and cortical thickness via voxel- and surface-based morphometry, respectively. A significant decrease of loss aversion in patients, unrelated to their impaired executive/working-memory performance, reflected the reduction of posterior fronto-medial grey matter density and right frontopolar cortical thickness. Rather than their executive deficits, patients' reduced loss aversion reflects the structural damage of the posterior fronto-medial cortex previously associated with solving conflicts at the response level, where earlier functional magnetic resonance imaging (fMRI) studies have shown a 'neural loss aversion' pattern of steeper deactivation for losses than activation for gains, and of the frontopolar cortex in charge of managing competing goals. These findings highlight possible directions for addressing AUD patients' high relapse rate, for example, cognitive-behavioural rehabilitative interventions enhancing the awareness of the adverse outcomes of addiction or neurostimulation protocols targeting the regions processing their salience.

Framing and self-responsibility modulate brain activities in decision escalation

Background

Escalation of commitment is a common bias in human decision making. The present study examined (1) differences in neural recruitment for escalation and de-escalation decisions of prior investments, and (2) how the activations of these brain networks are affected by two factors that can arguably modulate escalation decisions: (i) self-responsibility, and (ii) framing of the success probabilities.

Results

Imaging data were obtained from functional magnetic resonance imaging (fMRI) applied to 29 participants. A whole-brain analysis was conducted to compare brain activations between conditions. ROI analysis, then, was used to examine if these significant activations were modulated by two contextual factors. Finally, mediation analysis was applied to explore how the contextual factors affect escalation decisions through brain activations. The findings showed that (1) escalation decisions are faster than de-escalation decisions, (2) the corresponding network of brain regions recruited for escalation (anterior cingulate cortex, insula and precuneus) decisions differs from this recruited for de-escalation decisions (inferior and superior frontal gyri), (3) the switch from escalation to de-escalation is primarily frontal gyri dependent, and (4) activation in the anterior cingulate cortex, insula and precuneus were further increased in escalation decisions, when the outcome probabilities of the follow-up investment were positively framed; and activation in the inferior and superior frontal gyri in de-escalation decisions were increased when the outcome probabilities were negatively framed.

Conclusions

Escalation and de-escalation decisions recruit different brain regions. Framing of possible outcomes as negative leads to escalation decisions through recruitment of the inferior frontal gyrus. Responsibility for decisions affects escalation decisions through recruitment of the superior (inferior) gyrus, when the decision is framed positively (negatively).