Response-locked Event-related Potentials Research Articles

Different methods to define utility functions yield similar results but engage different neural processes

Although the concept of utility is fundamental to many economic theories, up to now a generally accepted method determining a subject's utility function is not available. We investigated two methods that are used in economic sciences for describing utility functions by using response-locked event-related potentials in order to assess their neural underpinnings. For determining the certainty equivalent, we used a lottery game with probabilities to win p = 0.5, for identifying the subjects’ utility functions directly a standard bisection task was applied. Although the lottery tasks’ payoffs were only hypothetical, a pronounced negativity was observed resembling the error related negativity (ERN) previously described in action monitoring research, but this occurred only for choices far away from the indifference point between money and lottery. By contrast, the bisection task failed to evoke an remarkable ERN irrespective of the responses’ correctness. Based on these findings we are reasoning that only decisions made in the lottery task achieved a level of subjective relevance that activates cognitive-emotional monitoring. In terms of economic sciences, our findings support the view that the bisection method is unaffected by any kind of probability valuation or other parameters related to risk and in combination with the lottery task can, therefore, be used to differentiate between payoff and probability valuation.

Flanker-Task in Children

Response processing may comprise multiple systems working in parallel at different functional levels of performance monitoring. In time-frequency decompositions of response-locked event-related potentials from adults, a subprocess operating in the delta frequency band was interpreted as an index of cognitive error monitoring, distinguishable from a process with theta frequency probably related to motor control. However, it remains unclear whether such subprocesses can also be distinguished in children. In the current study, error processing was assessed in 22 normal boys aged 8 to 15 years using an Erikson Flanker task. Performance data revealed the expected indices of conflicting task demands, such as increased reaction times and error rates. A clear error-negativity was found in the response-locked event-related potentials after incompatible stimuli, and correct responses show a slow negative deflection immediately preceding the button-press, which is absent in errors. Time-frequency decompositions disclosed that a subprocess in the lower delta band preceding correct responses may reflect a more general action monitoring process sensitive to conflicting task demands that, moreover, may prevent one from making an error if it is active early enough. Processes in the delta and theta bands are modulated specifically by errors and may index motor-related monitoring in children. Moreover, these processes occurred considerably earlier for correct responses compared to errors, suggesting that their timing reflects some performance capacity. These considerations may help to clarify response processing in tasks with conflicting demands.

Brain potentials reveal the role of conflict in human errorful and errorless learning

The avoidance of errors during learning, so-called errorless learning, results in increased memory performance. In the present study subjects had to learn items in an errorful and an errorless manner. After each learning session learned items were presented again, but now intermixed with items not learned before. Response-locked event-related potentials were used to investigate the neural underpinnings of cognitive control mechanisms during recognition of items learned under errorless and errorful conditions. Irrespective of the response's correctness a typical error-related negativity (ERN) was observed for items classified as learned before. In contrast to the apparent difference in memory performance between learning modes, ERN amplitudes to hits and false alarms were not different. The present pattern of results can be explained neither in terms of error detection nor the conflict monitoring account. Instead we are trying to argue that the findings add support to a theoretical proposal which posits that variations of the ERN amplitude can be best explained by the subjects' perceived likelihood of making an error.

Alterations in the Cognitive Control of Action Monitoring with a History of Concussion

Retired athletes reporting multiple sport-related concussions evidence increased rates and severity of neurodegenerative diseases. Yet, younger athletes with multiple sport-related concussions perform normally on standard clinical assessments of cognitive functioning. More sensitive measures of cognitive functioning may clarify the foundation for performance differences between these two groups. PURPOSE: This investigation sought to evaluate the effect of multiple concussions on neuroelectric and task performance indices of the cognitive control of action monitoring. METHODS: Sixty-three athletes (19 female; 19.6 ± 1.2 yrs) with variable concussion histories completed a clinical neurocognitive assessment and a modified flanker task. The Error-related Negativity (ERN) of the response-locked event-related brain potential was recorded during performance of the flanker task. Participants were divided into groups according to the self-report number of physician-diagnosed concussions (0, 1+). RESULTS: Analyses revealed no significant differences between groups on the clinical neurocognitive assessment. However, increased ERN amplitude and a more diffuse topography were observed in individuals reporting one or more concussions, relative to those without a history of concussion. CONCLUSION: These findings demonstrate that those individuals with a history of concussion have an inefficient action monitoring system as indexed by ERN amplitude, which reflects the evaluation of conflict and signals for alterations in topdown cognitive control. Further, increased diffusion of the ERN signal may indicate the recruitment of compensatory processes due to decrements in areas of the brain that mediate the evaluation of conflict. Given that the neuroelectric differences exist in the absence of disparities in standard clinical assessment, the findings indicate that measures of the neuroelectric system may be more sensitive to signs of chronic cognitive dysfunction due to concussion. Supported by the Mary Jane Neer Research Fund:

Error and Deviance Processing in Implicit and Explicit Sequence Learning

In this experiment, we examined the extent to which error-driven learning may operate under implicit learning conditions. We compared error monitoring in a sequence learning task in which stimuli consisted of regular, irregular, or random sequences. Subjects were either informed (explicit condition) or not informed (implicit condition) about the existence of the sequence. For both conditions, reaction times were faster to stimuli from regular sequences than from random sequences, thus supporting the view that sequence learning occurs irrespective of learning condition. Response-locked event-related potentials (ERPs) showed a pronounced ERN/Ne, thereby signaling the detection of committed errors. Deviant stimuli from irregular sequences elicited an N2b component that developed in the course of the experiment, albeit faster for explicit than implicit learners. This observation supports the view that deviant events acquire the status of perceived errors during explicit and implicit learning, and thus, an N2b is generated resembling the ERN/Ne to committed errors. While performing the task, expectations about upcoming events are generated, compared to the actual events, and evaluated on the dimension "better or worse than expected." The accuracy of this process improves with learning, as shown by a gradual increase in N2b amplitude as a function of learning. Additionally, a P3b, which is thought to mirror conscious processing of deviant stimuli and is related to updating of working memory representations, was found for explicit learners only.

The interaction of task-relevant and task-irrelevant stimulus features in the number/size congruency paradigm: An ERP study

We studied whether task-relevant numerical information and task-irrelevant physical size information interact during perceptual and/or response processing in the number/size congruency paradigm (NSCP). Participants decided which of two simultaneously presented numbers was larger numerically. The physical size of numbers delivered neutral, congruent, or incongruent information with numerical magnitude. Both stimulus- and response-locked event-related brain potentials (ERPs) were analyzed. The lateralized readiness potential (LRP) was used for indexing motor preparation. Similar early facilitation and interference effects appeared in the amplitude of ERPs between 150 and 250 ms after stimulus presentation, focused over parieto-occipital electrode-sites. We conclude that these effects reflected a similar process in both facilitation and interference, related to a general increase of processing load and/or conflict detection. Further, we have replicated our former findings demonstrating late facilitation and interference effects between 300 and 430 ms. These effects may be related to the conflict monitoring and response-selection activity of the anterior cingulate cortex, or may be related to higher level contextual analysis. Our findings suggest that facilitation and interference effects appear at multiple levels of stimulus and response processing. We have also demonstrated ERP amplitude effects as a function of numerical difference between the to-be-compared numbers both in stimulus- and response-locked ERPs.

Out-of-Synch and Out-of-Sorts: Dysfunction of Motor-Sensory Communication in Schizophrenia

Phase synchronization of neural activity preceding a motor act may reflect an efference copy of the motor plan and its expected sensory consequences (corollary discharge), which is sent to sensory cortex to herald the arrival of self-generated sensations and dampen the resulting sensory experience. We performed time-frequency decomposition of response-locked electroencephalogram (EEG) to examine phase synchronization of oscillations across trials (phase-locking factor [PLF]) to self-paced button presses. If prepress PLF reflects the activity in motor cortex, it should be contralateralized. If it reflects the action of the efference copy, it should be related to subsequent sensory suppression. If efference copy/corollary discharge mechanisms are abnormal in schizophrenia, it should be reduced in patients with schizophrenia. Electroencephalogram was collected while 23 patients (20 schizophrenia; 3 schizoaffective) and 25 age-matched control subjects pressed a button, at will, every 1 to 2 sec. Phase-locking factor preceding and following button presses was calculated from single-trial EEG; averaging single trials yielded response-locked event-related potentials (ERPs) to the tactile response associated with button pressing. Consistent with its hypothesized reflection of efference copy/corollary discharge signals, prepress gamma band neural synchrony was 1) maximal over the contralateral sensory-motor cortex in healthy subjects, 2) correlated with the ipsilateralized somatosensory ERP amplitude evoked by the press, and 3) reduced in patients. Prepress neural synchrony in the beta band was also reduced in patients, especially those with avolition/apathy. These data are consistent with dysfunction of forward model circuitry in schizophrenia and suggest that the specific motor-sensory system affected is selectively linked to symptoms involving that system.

The Development of Control Processes Supporting Source Memory Discrimination as Revealed by Event-related Potentials

Improvement in source memory performance throughout childhood is thought to be mediated by the development of executive control. As postretrieval control processes may be better time-locked to the recognition response rather than the retrieval cue, the development of processes underlying source memory was investigated with both stimulus- and response-locked event-related potentials (ERPs). These were recorded in children, adolescents, and adults during a recognition memory exclusion task. Green- and red-outlined pictures were studied, but were tested in black outline. The test requirement was to endorse old items shown in one study color ("targets") and to reject new items along with old items shown in the alternative study color ("nontargets"). Source memory improved with age. All age groups retrieved target and nontarget memories as reflected by reliable parietal episodic memory (EM) effects, a stimulus-locked ERP correlate of recollection. Response-locked ERPs to targets and nontargets diverged in all groups prior to the response, although this occurred at an increasingly earlier time point with age. We suggest these findings reflect the implementation of attentional control mechanisms to enhance target memories and facilitate response selection with the greatest and least success, respectively, in adults and children. In adults only, response-locked ERPs revealed an early-onsetting parietal negativity for nontargets, but not for targets. This was suggested to reflect adults' ability to consistently inhibit prepotent target responses for nontargets. The findings support the notion that the development of source memory relies on the maturation of control processes that serve to enhance accurate selection of task-relevant memories.

Cue- versus response-locked processes in backward inhibition: Evidence from ERPs

A task set may need to be inhibited to facilitate the switch to another task. This event-related potential (ERP) study determined (1) whether backward inhibition (BI) is exerted preferentially in high interference environments, and (2) whether ERPs locked to critical time points reflect BI during cue preparation and/or response stages. High interference (HI) and low interference (LI) were created by manipulating task difficulty. A reaction time (RT) BI effect (i.e., BI>control trials) was shown only during HI tasks. Cue-locked ERPs on LI tasks suggest increased attentional resources were allocated during the reactivation of a recently inhibited task. For HI tasks, BI versus control trial differences were reflected in a response-locked ERP negativity only after response selection (indexed by the response-locked lateralized readiness potential), indicating that BI is a lateral inhibition mechanism exerted during response preparation.

Cardiorespiratory Fitness, Acute Aerobic Exercise, and Action Monitoring

The study of physical activity and cardiorespiratory fitness influences on cognitive and behavioral functioning has grown in interest over recent decades. The beneficial effect of exercise and fitness on cognition appears to be a robust phenomenon, with a stronger relationship to selective aspects of cognitive function involving extensive amounts of executive control. However, to date, the influences of an acute bout of exercise and cardiorespiratory fitness on indices of action monitoring have not been examined. PURPOSE: To study the influences of cardiorespiratory fitness and acute aerobic exercise on the behavioral and neuroelectric indices of action monitoring using a flanker task paradigm. METHOD: Twenty-eight (14 female) adults (18–22 years) were recruited based on maximal oxygen uptake (VO max) achieved during a graded maximal exercise test (GXT) such that an equal number of participants were placed into gender-balanced higher- and lower-fit groups. The error-related negativity (ERN) component of a response-locked event-related brain potential and behavioral measures of response speed, accuracy, and post-error slowing were measured during the completion of a flanker task following a 30-minute acute bout of aerobic exercise on a treadmill and following a 30-minute rest period for all participants. RESULTS: Results indicated that higher-fit adults exhibited increased post-error response slowing compared to lower-fit adults. No such group effects were observed for response accuracy. ERN findings replicated previous action monitoring studies with larger amplitude following error, relative to correct, trials at the FCz electrode site. Further, higher-fit adults exhibited reduced ERN amplitude compared to lower-fit adults. No such effects of acute aerobic exercise were evident for ERN amplitude or behavioral measures of action monitoring. CONCLUSION: These findings suggest that cardiorespiratory fitness exerts a beneficial influence on both behavioral and neuroelectric indices of action monitoring by increasing top-down executive control while acute aerobic exercise does not produce a meaningful effect on these measures. Supported by: NIH/NIAAG21188 (PI: Hillman)

Reduced punishment sensitivity in neural systems of behavior monitoring in impulsive individuals

This study measured the response-locked event-related potential during a flanker task with performance-based monetarily rewarding and punishing trials in 37 undergraduate students separated into high- and low-impulsive groups based on a median split on self-reported Barrett Impulsiveness Scale. The high-impulsive group had a smaller medial frontal error-related negativity (ERN) on punishment trials than the low-impulsive group. The medial prefrontal neural system of behavior monitoring, indexed by the ERN, appears less sensitive to punishment signals in normal impulsivity. This reduced punishment sensitivity in impulsivity, a personality variation associated with several mental and personality disorders including ADHD and substance abuse may be related to the tendency to select short-term rewards despite potential long-term negative consequences in these individuals.

Affective and cognitive modulation of performance monitoring: Behavioral and ERP evidence

This study investigates the effects of negative affect on performance monitoring. EEG was acquired during a lateralized, numeric Stroop working memory task that featured task-irrelevant aversive and neutral pictures between stimuli. Performance accuracy showed a right-hemisphere advantage for stimuli that followed aversive pictures. Response-locked event-related potentials (ERPs) from accurate trials showed an early negative component (CRN; correct response/conflict-related negativity) followed by a positive wave comparable to the Pe (error positivity). The CRN was bi-peaked with an earlier peak that was sensitive to aversive pictures during early portions of the experiment and a later peak that increased with error likelihood later in the experiment. Pe amplitude was increased with aversive pictures early in the experiment and was sensitive to picture type, Stroop interference, and hemisphere of stimulus delivery during later trials. This suggests that ERP indices of performance monitoring, the CRN and Pe, are dynamically modulated by both affective and cognitive demands.

Exploration des troubles attentionnels des traumatisés crâniens avec les potentiels évoqués cognitifs

Objective. – To specify, in cognitive processing leading to an action, the localization of difficulties in attention following severe, traumatic brain injury. Method. – Stimulus-locked and response-locked event-related potentials were recorded during a Stroop task in 25 patients with traumatic brain injury and 25 control subjects approximately 4 months after the accident. The latency and amplitude of the waves were compared between the two groups and correlated with clinical data. Results. – The reaction times of brain-injured patients were significantly longer than those of the control group, but neither the number of errors nor the interference differed between the groups. Electrophysiological recordings showed early abnormalities between 100 and 200 ms after stimulus onset. The key area could be the medial occipitotemporal side connected with frontal regions. Recordings also showed disruptions in motor program monitoring, which implied frontomedial areas. Conclusion. – This protocol allows for precisely dating cognitive abnormalities. Future studies should relate cognitive with neuropsychological abnormalities and examine the possibilities of later regression.

Age and physical activity influences on action monitoring during task switching

Behavioral and neuroelectric indices of action monitoring were compared for 53 high and low physically active older (60–71 years) and younger (18–21 years) adults during a task-switching paradigm in which they performed a task repeatedly or switched between two different tasks. The error-related negativity (ERN) of a response-locked event-related brain potential (ERP) and behavioral measures of response speed and accuracy were measured during the heterogeneous condition (switching randomly between two tasks) of the switch task. Results indicated that older adults exhibited a greater relative slowing in RT during heterogeneous blocks and smaller ERN amplitude compared to younger adults. Additionally, physical activity differences revealed a relatively smaller global switch cost for physically active older adults and decreased ERN amplitude, as well as increased post-error response slowing for older and younger physically active participants, compared to their less physically active counterparts. The findings suggest that both age and physical activity participation influence behavioral and neuroelectric indices of action monitoring and provide further evidence for the beneficial effects of physical activity on executive control.

Age differences in attentional control: An event‐related potential approach

We examined age differences in event-related potentials (ERPs) associated with attentional control of task-set selection and response interference by means of a cue-based switching paradigm in which participants performed the color or word Stroop task. The results of ERPs in the cue interval indicated that P3 latencies were slowed for older adults, suggesting age-related slowing in updating currently relevant task sets. Older adults also showed a larger CNV under switching than nonswitching conditions, indicating age differences in maintaining task sets over longer periods of time. The results of target-locked ERPs revealed a negativity to incompatible Stroop trials (Ni) that was prolonged for older adults, suggesting age differences in early conflict processing. Response-locked ERPs showed a negative deflection to incompatible Stroop trials (CRN) only for younger adults, suggesting age differences also in response-related conflict processing.

Decomposing ERP time–frequency energy using PCA

Objective Time–frequency transforms (TFTs) offer rich representations of event-related potential (ERP) activity, and thus add complexity. Data reduction techniques for TFTs have been slow to develop beyond time analysis of detail functions from wavelet transforms. Cohen's class of TFTs based on the reduced interference distribution (RID) offer some benefits over wavelet TFTs, but do not offer the simplicity of detail functions from wavelet decomposition. The objective of the current approach is a data reduction method to extract succinct and meaningful events from both RID and wavelet TFTs. Methods A general energy-based principal components analysis (PCA) approach to reducing TFTs is detailed. TFT surfaces are first restructured into vectors, recasting the data as a two-dimensional matrix amenable to PCA. PCA decomposition is performed on the two-dimensional matrix, and surfaces are then reconstructed. The PCA decomposition method is conducted with RID and Morlet wavelet TFTs, as well as with PCA for time and frequency domains separately. Results Three simulated datasets were decomposed. These included Gabor logons and chirped signals. All simulated events were appropriately extracted from the TFTs using both wavelet and RID TFTs. Varying levels of noise were then added to the simulated data, as well as a simulated condition difference. The PCA-TFT method, particularly when used with RID TFTs, appropriately extracted the components and detected condition differences for signals where time or frequency domain analysis alone failed. Response-locked ERP data from a reaction time experiment was also decomposed. Meaningful components representing distinct neurophysiological activity were extracted from the ERP TFT data, including the error-related negativity (ERN). Conclusions Effective TFT data reduction was achieved. Activity that overlapped in time, frequency, and topography were effectively separated and extracted. Methodological issues involved in the application of PCA to TFTs are detailed, and directions for further development are discussed. Significance The reported decomposition method represents a natural but significant extension of PCA into the TFT domain from the time and frequency domains alone. Evaluation of many aspects of this extension could now be conducted, using the PCA-TFT decomposition as a basis.

Error-preceding brain activity: Robustness, temporal dynamics, and boundary conditions

A recent study reported a positive modulation of the response-locked event-related brain potential (ERP) on trials preceding errors (i.e., error − 1 trials). It was proposed that this error-preceding positivity (EPP) reflects the disengagement of the response monitoring system prior to errors. In three studies, we sought to replicate the EPP, and to delineate the conditions under which it can be observed. Study 1 replicated the finding of a positive modulation of the ERP on error-preceding compared to RT-matched correct-preceding trials. This enhanced positivity was not due to differences in stimulus-related processing, and a similar modulation was not observed on error − 2 or error + 1 trials. Studies 2 and 3 indicated that similar EPP-like phenomena could be observed across a variety of tasks, and using much longer inter-trial intervals. The onset and duration of the modulation, however, did vary between studies. These results are discussed in terms of response-locked ERPs and action monitoring.

Psychophysiological evidence that the SNARC effect has its functional locus in a response selection stage

When participants judge the parity of visually presented digits, left-hand responses are faster for numerically small numbers, whereas right-hand responses are faster for large numbers [SNARC effect; S. Dehaene, S. Bossini, P. Giraux, The mental representation of parity and number magnitude. J. Exp. Psychol. Gen., 122, (1993) 371–396]. The present study aimed to find more direct evidence for the functional locus of this effect by recording brain waves while participants performed speeded parity judgments giving manual responses. Our results show clear and robust SNARC effects in the response-locked event-related potentials (ERPs) compared to the stimulus-locked ERPs, confirming that the SNARC effect arises during response-related rather than stimulus-related processing stages. Further analyses of lateralized readiness potentials strongly suggest that the SNARC effect begins to emerge in a response-related stage prior to response preparation and execution, more specifically, in a response selection stage.

Analyzing a complex visuomotor tracking task with brain-electrical event related potentials

Non-invasive techniques such as neuroimaging and event-related potential (ERP) methods have dramatically enhanced our understanding of the human brain. According to the requirements of the applied method, it is useful to simplify tasks for methodological reasons. In the present study we tested whether ERP measures are also suitable for analyzing complex tasks. In order to do this, we developed an analysis strategy based on the post hoc analysis of the behavioural data. We applied this method to a pursuit-tracking task of 25 s trial duration, consisting of repeated and non-repeated waveforms, where subjects had to track a target cross with a mouse-controlled cursor cross. An EEG was recorded from 62 channels. Response-locked ERPs were computed for two types of error correction: the correction of errors induced externally by the change of target direction and of internal errors generated by the subject itself. We found several ERP components that could be assigned to different feedback and feedforward controlled processing steps in the frontoparietal circuitry underlying visuomotor control, such as movement planning, movement execution (motor potential), reafferent activity, visuospatial analysis, and attentional (P300) processes. Our results support newer models that propose a role for the posterior parietal cortex in integrating multimodal sensory information. In addition, fast (about 180 ms and probably facilitated by anticipation) and slow (about 230–260 ms) error corrections could be differentiated by the time course of ERP activity. Our results show that complex (motor) tasks can be investigated with ERPs. This opens fruitful perspectives for future research on motor control in an ecological setting.

Event-Related Potentials in a Decision-Making Task with Delayed and Immediate Reward Conditions

Abstract: We investigated performance monitoring of a group of healthy normal subjects in a delay of gratification paradigm. Focusing on response-locked event-related brain potentials we observed an Ne-Pe-like complex in all conditions. While there was no modulation of the Ne-like component, the subsequent Pe-like positivity was largest in conditions in which subjects went for the largest immediate reward, regardless of whether this was disadvantageous (i.e., foreclosed a larger delayed reward) or not. We interpreted the positivity as mainly reflecting the size of the immediate reward.