Hiroaki Masaki

Affective-motivational influences on feedback-related ERPs in a gambling task

Theories have proposed that both the stimulus-preceding negativity (SPN) and the medial frontal negativity (MFN) reflect affective/motivational processing. We examined the effect of the motivational impact of feedback stimuli on these ERPs using a simple gambling task, focusing on the influence of prior losses and gains on ERPs and choice behavior. Choices were riskier following large losses than following small losses or large gains. The MFN, however, was larger following larger gains. The SPN preceding the outcome was also larger after a greater gain. Thus, we confirmed that both the MFN and the SPN respond to the motivational properties of the feedback. A dissociation between risk-taking behavior and these ERPs suggests that there could be two monitoring systems: one that leads to riskier responses following losses and a second that leads to heightened expectancy.

An electrophysiological study of the locus of the interference effect in a stimulus-response compatibility paradigm

This study investigated the locus of the interference effect in a stimulus-response compatibility task using event-related potentials (ERPs). Ten participants were instructed to respond to stimulus color with the left or right middle finger. Red or blue arrows pointed in the same direction as the response hand on congruent trials and pointed in the opposite direction on incongruent trials. Neutral trials were red or blue horizontal bars. Reaction times (RTs) to incongruent stimuli were significantly longer than RTs to congruent stimuli. The peak latency of the P300 for incongruent stimuli was significantly longer than that for congruent stimuli. In addition, onset of stimulus-locked lateralized readiness potential (LRPs) was significantly later for incongruent stimuli than for congruent stimuli. However, electromyogram (EMG)-locked LRPs for incongruent stimuli showed incorrect preparation. These results suggest that the interference effect might occur at the stage in which stimulus evaluation processes and response-related processes overlap.

Error-related brain potentials elicited by vocal errors.

Error-related negativity (ERN) is observed immediately after an error in choice reaction time tasks performed by hand response. We examined whether the ERN occurs in relation to slips of vocalization in the Stroop color word task. In one condition, the subjects vocal responses were masked by continuous pink noise in order to prevent vocalization-related cortical potentials from contaminating the ERN time window. This masking procedure was successful in inhibiting the vocalization-related cortical potential. More importantly, vocalization errors elicited a frontocentral negative-going deflection followed by a positive component immediately after the error response regardless of the masking condition. The present results suggest that the error detection mechanism may also elicit an ERN-like component in response to vocal slips.

The effect of sleepiness on performance monitoring : I know what I am doing, but do I care?

The behavioral, cognitive, and psychophysiological effects of extended wakefulness are well known. As time awake increases, errors become more common and are often attributed to lapses in attention. Such lapses can be reflected in the error‐related negativity (Ne/ERN), a negative electroencephalogram deflection occurring after errors and is thought to be related to error detection or response conflict. Following the Ne/ERN, a positive deflection (error positivity, Pe) is also observed and is thought to reflect further evaluation of the error. To elicit Ne/ERNs, the Eriksen Flanker Task was administered to 17 women (aged 19–45 years) at two levels of alertness (4 and 20 h awake). After extended wakefulness, participants reported being subjectively sleepier and performing worse, but showed no significant difference in subjective effort. Across alertness conditions, they reported a similar number of subjective errors which closely matched an objective analysis of the errors. The Ne/ERN was not significantly reduced by sleepiness in contrast to the Pe which was reduced. Behavioral slowing after errors was larger in the alert than in the sleepy condition. These results show that after 20 h of wakefulness, individuals are reacting to their errors. However, further evaluation of the error, and remediation of these errors may be impaired despite continued effort.

Stimulus-preceding negativity is modulated by action-outcome contingency

We investigated the relationship between action-outcome contingency and stimulus-preceding negativity (SPN), a motivationally sensitive event-related potential. Neuroimaging studies have shown that insular cortex (a known source of the SPN) is more activated prior to rewards that are contingent on prior correct action than rewards that are given gratuitously. We compared two gambling tasks, one in which the participant attempted to guess the profitable key-press option (choice) and one in which rewards were simply given at random (no-choice). The SPN that developed in anticipation of feedback was larger in the choice condition, especially at right anterolateral sites. These findings suggest that the SPN specifically reflects the expectation of response reinforcement, rather than anticipatory attention toward emotionally salient stimuli.

Performance monitoring during sleep inertia after a 1‐h daytime nap

Performance monitoring is an essential function involved in the correction of errors. Deterioration of this function may result in serious accidents. This function is reflected in two event‐related potential (ERP) components that occur after erroneous responses, specifically the error‐related negativity/error negativity (ERN/Ne) and error positivity (Pe). The ERN/Ne is thought to be associated with error detection, while the Pe is thought to reflect motivational significance or recognition of errors. Using these ERP components, some studies have shown that sleepiness resulting from extended wakefulness may cause a decline in error‐monitoring function. However, the effects of sleep inertia have not yet been explored. In this study, we examined the effects of sleep inertia immediately after a 1‐h daytime nap on error‐monitoring function as expressed through the ERN/Ne and Pe. Nine healthy young adults participated in two different experimental conditions (nap and rest). Participants performed the arrow‐orientation task before and immediately after a 1‐h nap or rest period. Immediately after the nap, participants reported an increased effort to perform the task and tended to estimate their performance as better, despite no objective difference in actual performance between the two conditions. ERN/Ne amplitude showed no difference between the conditions; however, the amplitude of the Pe was reduced following the nap. These results suggest that individuals can detect their own error responses, but the motivational significance ascribed to these errors might be diminished during the sleep inertia experienced after a 1‐h nap. This decline might lead to overestimation of their performance.

The error-related negativity associated with different strength of stimulus–response interference

OBJECTIVE The present study was aimed at clarifying the effect of stimulus-response compatibility (SRC) interference on the ERN. METHODS We compared ERNs in two tasks differing in the level of interference, an arrow (AR) task classified as a Simon task and a more complex arrow-orientation (AO) task classified as a spatial-Stroop task. We also compared ERNs between partial errors (with initial incorrect movement corrected by a proper full response) and overt (uncorrected) errors. RESULTS Behavioral response time and error rate indicated that both interference and ERN amplitude were larger for the AO task than for the AR task. There was no significant difference in the ERN amplitude between the partial and overt errors. CONCLUSIONS The ERN becomes larger as a function of the SRC interference. SIGNIFICANCE Our study presented evidence that the ERN may represent response-monitoring associated with the SRC interference.

Gray matter volume and rapid decision-making in major depressive disorder

BACKGROUND Reduced motivation and blunted decision-making are key features of major depressive disorder (MDD). Patients with MDD show abnormal decision-making when given negative feedback regarding a reward. The brain mechanisms underpinning this behavior remain unclear. In the present study, we examined the association between rapid decision-making with negative feedback and brain volume in MDD. METHODS Thirty-six patients with MDD and 54 age-, sex- and IQ-matched healthy subjects were studied. Subjects performed a rapid decision-making monetary task in which participants could make high- or low-risk choices. We compared between the 2 groups the probability that a high-risk choice followed negative feedback. In addition, we used voxel-based morphometry (VBM) to compare between group differences in gray matter volume, and the correlation between the probability for high-risk choices and brain volume. RESULTS Compared to the healthy group, the MDD group showed significantly lower probabilities for high-risk choices following negative feedback. VBM analysis revealed that the MDD group had less gray matter volume in the right medial prefrontal cortex and orbitofrontal cortex (OFC) compared to the healthy group. The right OFC volume was negatively correlated with the probability that a high-risk choice followed negative feedback in patients with MDD. We did not observe these trends in healthy subjects. CONCLUSIONS Patients with MDD show reduced motivation for monetary incentives when they were required to make rapid decisions following negative feedback. We observed a correlation between this reduced motivation and gray matter volume in the medial and ventral prefrontal cortex, which suggests that these brain regions are likely involved in the pathophysiology of aberrant decision-making in MDD.

The influence of emotions due to verbal admonishment and encouragement on performance monitoring

This study investigated the relationship between emotion and performance monitoring as reflected in the error negativity/error-related negativity (Ne/ERN). Data were collected by using a spatial Stroop task from 15 female students of a university tennis club. After errors, participants received verbal feedback-recorded admonishments or encouragements spoken by their team captain. In a control condition no feedback was given after errors. Verbal admonishment decreased the ERN relative to the control condition, indicating impaired performance monitoring in line with somewhat larger compatibility effects in this condition. Source localization indicated a shift of the ERN toward more rostral zones within the anterior cingulate cortex indicating the involvement of affective processes.

Neural mechanisms of timing control in a coincident timing task

Many ball sports such as tennis or baseball require precise temporal anticipation of both sensory input and motor output (i.e., receptor anticipation and effector anticipation, respectively) and close performance monitoring. We investigated the neural mechanisms underlying timing control and performance monitoring in a coincident timing task involving both types of anticipations. Peak force for two time-to-peak force (TTP) conditions—recorded with a force-sensitive key—was required to coincide with a specific position of a stimulus rotating either slow or fast on a clock face while the contingent negative variation (CNV) and the motor-elicited negativity were recorded. Absolute timing error was generally smaller for short TTP (high velocity) conditions. CNV amplitudes increased with both faster stimulus velocity and longer TTPs possibly reflecting increased motor programming efforts. In addition, the motor-elicited negativity was largest in the slow stimulus/short TTP condition, probably representing some forms of performance monitoring as well as shorter response duration. Our findings indicate that the coincident timing task is a good model for real-life situations of tool use.