Neural correlates of individual differences in aversion to risk and choice inconsistencies

Most people tend to prefer smaller certain gains to large uncertain gains when making financial choices (risk aversion). However, attitudes toward risk vary greatly between individuals, and over time within individuals. Consistent behavior may reflect the adoption by the individual of a simple or automatized heuristic which reduces the subject's uncertainty about the outcome of a behavioral choice. In contrast inconsistent behavior may reflect the adoption of a "fuzzy" logic, likely leaving high levels of uncertainty in the participant making the choice. Therefore, inconsistent behavior may often be associated with greater risk aversion. The use of simple/automatized heuristics may also lead to increased reliance on fast brain processes, whereas fuzzy heuristic may lead to lingering uncertainty. These two modes of processing may therefore lead to different brain dynamics. To examine these dynamics we recorded event-related brain potentials (ERPs) from 22 adults participants engaged in a task requiring choices between certain (but often smaller) gains and an uncertain (but often bigger) gains. Behavioral analyses allowed us to quantify choice consistency and risk aversion for each individual. Choice consistency was related to the amplitude of P200; risk aversion was related to modulation of the medial frontal negativity (MFN) as a function of choice uncertainty, to the amplitude of a late positive potential (LPP). These findings are consistent with the idea that differences in individuals' behavior when making financial choices may reflect variations in the type of heuristics they adopt, which in turn may may be reflected in differences in brain dynamics.

Dissociation of Proactive and Reactive Cognitive Control in Individuals with Schizotypy: An Event-Related Potential Study

Objective: Patients with schizophrenia and individuals with schizotypy, a subclinical group at risk for schizophrenia, have been found to have impairments in cognitive control. The Dual Mechanisms of Cognitive Control (DMC) framework hypothesises that cognitive control can be divided into proactive and reactive control. However, it is unclear whether individuals with schizotypy have differential behavioural impairments and neural correlates underlying these two types of cognitive control. Method: Twenty-five individuals with schizotypy and 26 matched healthy controls (HCs) completed both reactive and proactive control tasks with electroencephalographic data recorded. The proportion of congruent and incongruent trials was manipulated in a classic colour-word Stroop task to induce proactive or reactive control. Proactive control was induced in a context with mostly incongruent (MI) trials and reactive control in a context with mostly congruent (MC) trials. Two event-related potential (ERP) components, medial frontal negativity (MFN, associated with conflict detection) and conflict sustained potential (conflict SP, associated with conflict resolution) were examined. Results: There was no significant difference between the two groups in terms of behavioural results. In terms of ERP results, in the MC context, HC exhibited significantly larger MFN (360–530 ms) and conflict SP (600–1000 ms) amplitudes than individuals with schizotypy. The two groups did not show any significant difference in MFN or conflict SP in the MI context. Conclusions: The present findings provide initial evidence for dissociation of neural activation between proactive and reactive cognitive control in individuals with schizotypy. These findings help us understand cognitive control deficits in the schizophrenia spectrum.

I’ll make you an offer you can refuse: How socially sensitive is the MFN?

Medial frontal negativity (MFN) is an event-related potential thought to originate in the anterior cingulate cortex. It is evoked by outcomes being worse than expected, such as when presented with unfair economic proposals during the Ultimatum Game (UG). This could mean the MFN indexes a social-emotional response, as commonly suggested in accounts that relate it to a violation of a social norm of fairness. To examine the link between MFN and norm violation, we designed an EEG experiment with participants acting as representatives in an UG. Participants responded either as themselves, or as representatives of two charities. Of these, a norm-compatible charity conformed to the participant’s values, while the norm-incompatible charity contrasted to them. The behavioural results showed that norm-incompatible representation reversed behaviour, with almost all fair offers being declined. The MFN, however, was unaffected by the norm representation, with unfair offers consistently evoking MFNs across conditions. We furthermore replicated the curious finding that unexpectedly generous offers evoke as much MFN as unfair offers. Thus, the MFN is not nearly as sensitive to higher-order social-emotional processes as commonly assumed. Instead, the perceived inequality that drives the MFN is likely due to a rational, probabilistic process.