Reward expectation modulates feedback-related negativity and EEG spectra

Abstract

The ability to evaluate outcomes of previous decisions is critical to adaptive decision-making. The feedback-related negativity (FRN) is an event-related potential (ERP) modulation that distinguishes losses from wins, but little is known about the effects of outcome probability on these ERP responses. Further, little is known about the frequency characteristics of feedback processing, for example, event-related oscillations and phase synchronizations. Here, we report an EEG experiment designed to address these issues. Subjects engaged in a probabilistic reinforcement learning task in which we manipulated, across blocks, the probability of winning and losing to each of two possible decision options. Behaviorally, all subjects quickly adapted their decision-making to maximize rewards. ERP analyses revealed that the probability of reward modulated neural responses to wins, but not to losses. This was seen both across blocks as well as within blocks, as learning progressed. Frequency decomposition via complex wavelets revealed that EEG responses to losses, compared to wins, were associated with enhanced power and phase coherence in the theta frequency band. As in the ERP analyses, power and phase coherence values following wins but not losses were modulated by reward probability. Some findings between ERP and frequency analyses diverged, suggesting that these analytic approaches provide complementary insights into neural processing. These findings suggest that the neural mechanisms of feedback processing may differ between wins and losses.

Frontal Feedback-Related Potentials in Nonhuman Primates: Modulation during Learning and under Haloperidol

“…The FRPs that we describe in monkeys are in many ways comparable to the medial frontal event-related potentials described in humans (Donkers et al, 2005;Cohen et al, 2007). Like human Figure 5.…”

“…The two signals, ERN and fERN, might reflect the same underlying mechanism (for review see Holroyd and Coles, 2002). These signals have since been correlated with subsequent behavioral adaptation suggesting a role in adjusting performance and in reinforcement learning (Gehring et al, 1993;Debener et al, 2005;Frank et al, 2005;Cohen et al, 2007;Taylor et al, 2007). The brain potential is sensitive to pharmacological challenges in particular when aminergic transmission is concerned.…”

The Processing of Unexpected Positive Response Outcomes in the Mediofrontal Cortex

“…As a consequence, feedback valence and expectancy in most studies are confounded. In studies investigating feedback processing in learning tasks, positive feedback is unexpected and negative feedback is expected in the beginning, and vice versa after learning has taken place Nieuwenhuis et al, 2002;Cohen et al, 2007;Holroyd et al, 2008;Opitz et al, 2011). This general criticism is not always applicable to studies using gambling tasks because this confound is easy to avoid in those paradigms.…”

EEG error-related potentials detection with a Bayesian filter

“…A wealth of experimental studies have shown electrophysiological signals elicited by erroneous actions [1]. Moreover, similar potentials have also been reported during Human-Machine interaction, including the operation of BrainComputer interfaces [2], [3].…”

“…These signals, elicited during user monitoring of the system performance, are similar to other error-related signals, i.e. feedback-related negativity [1], or interaction error-potential [2]. The waveform is characterized by a small positive peak near 200ms after delivery of feedback, followed by a negative deflection around 250ms.…”