Deconstructing the functional significance of the error-related negativity (ERN) and midline frontal theta oscillations using stepwise time-locking and single-trial response dynamics.

Error-related electroencephalographic potentials have been used for decades to develop theoretical models of response monitoring processes, study altered cognitive functioning in clinical populations, and more recently, to improve the performance of brain-computer interfaces. However, the vast majority of this research relies on discrete behavioral responses that confound error detection, response cancelation, error correction, and post-error cognitive and affective processes. By contrast, the present study demonstrates a novel, complementary method for isolating the functional correlates of error-related electroencephalographic responses using single-trial kinematic analyses of cursor trajectories and a stepwise time-locking analysis. The results reveal that the latency of the ERN, Pe, and medial-frontal theta oscillations are all strongly positively correlated with the latency at which an initiated error response is canceled, as indicated by the peak deceleration of the initiated movement prior to a corrective response. Results are discussed with respect to current theoretical models of error-related brain potentials and potential relevance to clinical applications.

Electrophysiological correlates of error initiation and response correction.

Adaptive, goal-directed behavior requires the ability to monitor the perception-action cycle, detect errors, and make adjustments to restore volitional action. One limiting factor in gaining a clearer understanding of the functional significance of the neural correlates of error detection has been the predominant use of discrete responses (e.g., a button press) as measures of behavior that do not easily afford an assessment of online error correction. This limitation was addressed in the current study by examining the neural correlates of error initiation and correction with respect to dynamic cursor movements that permitted measurement of the initiation and correction of errant responses within individual trials. Results indicate that the ERN may reflect a general error alarm following the initiation of an error but that the Pe component may be more closely related to the initiation of corrective action. The data also reveal that the amplitude and latency of frontal midline Theta oscillations may be more closely related to corrective action, suggesting that error detection and corrective action are mediated by an overlapping neural network.

Beyond the FN: A spatio-temporal analysis of the neural correlates of feedback processing in a virtual Blackjack game.

Studies using event-related brain potentials (ERPs) to examine feedback processing in gambling tasks have focused almost exclusively on components elicited between 200 and 500ms after feedback over the frontal-central region of the scalp (i.e., P2, feedback negativity (FN), and P3a). In contrast, studies examining the functional neuroanatomy of feedback processing reveal activation in a distributed network that includes the anterior and posterior cingulate, the lateral and medial orbitofrontal cortex, the occipital cortex, and the basal ganglia. In the current study, we used ERPs in combination with spatial principal components-massive univariate analysis and distributed source analysis to examine the time course, topography, and neural generators of ERPs elicited in a virtual Blackjack game from 0 to 2000ms after feedback was delivered. The ERP data revealed the P2-FN-P3a complex, as well as, broadly distributed transient and slow wave activity that was sensitive to the magnitude and valence of an outcome. The ERPs reflected activation in the anterior and posterior cingulate, in addition to the occipital, temporal and medial frontal cortices. These data demonstrate that ERPs can provide valuable insight into the timing of neural recruitment within a distributed cortical network during the first two seconds of feedback processing.

Event-related theta and gamma band oscillatory dynamics during visuo-spatial sequence memory in younger and older adults.

Visuo-spatial working memory (VSWM) for sequences is thought to be crucial for daily behaviors. Decades of research indicate that oscillations in the gamma and theta bands play important functional roles in the support of visuo-spatial working memory, but the vast majority of that research emphasizes measures of neural activity during memory retention. The primary aims of the present study were (1) to determine whether oscillatory dynamics in the Theta and Gamma ranges would reflect item-level sequence encoding during a computerized spatial span task, (2) to determine whether item-level sequence recall is also related to these neural oscillations, and (3) to determine the nature of potential changes to these processes in healthy cognitive aging. Results indicate that VSWM sequence encoding is related to later (∼700 ms) gamma band oscillatory dynamics and may be preserved in healthy older adults; high gamma power over midline frontal and posterior sites increased monotonically as items were added to the spatial sequence in both age groups. Item-level oscillatory dynamics during the recall of VSWM sequences were related only to theta-gamma phase amplitude coupling (PAC), which increased monotonically with serial position in both age groups. Results suggest that, despite a general decrease in frontal theta power during VSWM sequence recall in older adults, gamma band dynamics during encoding and theta-gamma PAC during retrieval play unique roles in VSWM and that the processes they reflect may be spared in healthy aging.

Temporal and Spectral Properties of the Auditory Mismatch Negativity and P3a Responses in Schizophrenia.

The mismatch negativity (MMN) event-related potential (ERP) indexes relatively automatic detection of changes in sensory stimuli and is typically attenuated in individuals with schizophrenia. However, contributions of different frequencies of electroencephalographic (EEG) activity to the MMN and the later P3a attentional orienting response in schizophrenia are poorly understood and were the focus of the present study. Participants with a schizophrenia-spectrum disorder (n = 85) and non-psychiatric control participants (n = 74) completed a passive auditory oddball task containing 10% 50 ms "deviant" tones and 90% 100 ms "standard" tones. EEG data were analyzed using spatial principal component analysis (PCA) applied to wavelet-based time-frequency analysis and MMN and P3a ERPs. The schizophrenia group compared to the control group had smaller MMN amplitudes and lower deviant-minus-standard theta but not alpha event-related spectral perturbation (ERSP) after accounting for participant age and sex. Larger MMN and P3a amplitudes but not latencies were correlated with greater theta and alpha time-frequency activity. Multiple linear regression analyses revealed that control participants showed robust relationships between larger MMN amplitudes and greater deviant-minus-standard theta inter-trial coherence (ITC) and between larger P3a amplitudes and greater deviant-minus-standard theta ERSP, whereas these dynamic neural processes were less tightly coupled in participants with a schizophrenia-spectrum disorder. Study results help clarify frequency-based contributions of time-domain (ie, ERP) responses and indicate a potential disturbance in the neural dynamics of detecting change in sensory stimuli in schizophrenia. Overall, findings add to the growing body of evidence that psychotic illness is associated with widespread neural dysfunction in the theta frequency band.

Behavioral and electrophysiological correlates of Simon and flanker conflict interference in younger and older adults.

Conflict processing and interference control have been popular topics of research in the study of pathological brain aging. However, there remains much to be learned about how these cognitive processes are altered in the course of healthy brain aging. Moreover, few studies have combined multiple measures of interference control using factorial designs. The aim of this study was to determine the nature of age-related changes in behavioral and electroencephalographic correlates of interference control using a factorial combination of the Simon and flanker interference conditions. Data were collected from a group of younger and high-functioning older adults. Behavioral results indicated the presence of conflict interference effects in both groups, that both Simon and flanker conflict effects are increased in high-functioning older adults, that the two types of conflict interference interact superadditively, and that older adults are more susceptible to the superadditive costs of multiple conflict types. ERP analyses revealed that early perceptual and response-selection processes are differentially modulated by flanker and Simon conflict respectively, however, there was no evidence that these early processes were impaired in older adults. Later components of the ERP in the P3 time range mirrored behavioral results, reflecting the increased susceptibility to flanker and Simon conflict in older adults.

Induced cortical gamma-band oscillations reflect cognitive control elicited by implicit probability cues in the preparing-to-overcome-prepotency (POP) task.

Previous research suggests that synchronous cortical gamma-band oscillations reflect the implementation of cognitive control in anticipation of the need to overcome prepotent responses. These studies often require participants to link task instructions with task cues signaling the need (or lack thereof) for cognitive control. Thus, the oscillatory response elicited by these cues may also reflect the implementation of explicit task instructions. The aim of this research was to determine whether gamma-band oscillations would also be increased in preparation for cognitive control when the need for that control was only made implicitly available to the participant. Using a task-ambiguous cue to indicate the position of a subsequent probe stimulus, we manipulated the need for cognitive control by varying the probability of high- and low-control probes appearing in each of two positions. Results show that participants developed the anticipated expectancies regarding probe identity in the two positions and that the anticipation of a high-control probe was associated with an increase in the power of induced cortical gamma band over frontal scalp recording sites.

Knowing we know before we know: ERP correlates of initial feeling-of-knowing.

Subjects performed a rapid feeling-of-knowing task developed by (Reder, L. M., & Ritter, F. (1992). What determines initial feeling of knowing? Familiarity with question terms, not with the answer. Journal of Experimental Psychology: Learning, Memory, and Cognition, 18, 435-451), while event-related potentials (ERPs) were recorded to identify the time course of "feeling-of-knowing" signals. Subjects were shown a series of math problems, some of which were repeated multiple times during the course of the experiment, and subjects had to rapidly decide whether the answer to a given problem could be quickly retrieved from memory (retrieval trials) or had to be calculated on scrap paper (calculate trials). Behavioral results replicated the 1992 study, showing that subjects can estimate whether the answer is known much faster than the answer can be retrieved. ERPs time-locked to the onset of the math problem showed that accurate retrieval trials were associated with greater positivity for an early frontal P2 component (epoched from 180 to 280ms) and a frontal-central P3 component (epoched from 300 to 550ms). Moreover, this feeling-of-knowing signal was not found for subjects who never obtained a successful on-time retrieval. We interpret these findings as suggesting that initial feeling-of-knowing relies on a rapid assessment of the "perceptual fluency" with which the stimulus is processed. If a stimulus is deemed sufficiently familiar, the activation level of an internal problem representation is used to arrive at a decision of whether to search for the answer or to calculate it.

Memory systems do not divide on consciousness: Reinterpreting memory in terms of activation and binding.

There is a popular hypothesis that performance on implicit and explicit memory tasks reflects 2 distinct memory systems. Explicit memory is said to store those experiences that can be consciously recollected, and implicit memory is said to store experiences and affect subsequent behavior but to be unavailable to conscious awareness. Although this division based on awareness is a useful taxonomy for memory tasks, the authors review the evidence that the unconscious character of implicit memory does not necessitate that it be treated as a separate system of human memory. They also argue that some implicit and explicit memory tasks share the same memory representations and that the important distinction is whether the task (implicit or explicit) requires the formation of a new association. The authors review and critique dissociations from the behavioral, amnesia, and neuroimaging literatures that have been advanced in support of separate explicit and implicit memory systems by highlighting contradictory evidence and by illustrating how the data can be accounted for using a simple computational memory model that assumes the same memory representation for those disparate tasks.

Contributions of spectral frequency analyses to the study of P50 ERP amplitude and suppression in bipolar disorder with or without a history of psychosis.

OBJECTIVE: The present study investigated event-related brain potential (ERP) indices of auditory processing and sensory gating in bipolar disorder and subgroups of bipolar patients with or without a history of psychosis using the P50 dual-click procedure. Auditory-evoked activity in two discrete frequency bands also was explored to distinguish between sensory registration and selective attention deficits. METHODS: Thirty-one individuals with bipolar disorder and 28 non-psychiatric controls were compared on ERP indices of auditory processing using a dual-click procedure. In addition to conventional P50 ERP peak-picking techniques, quantitative frequency analyses were applied to the ERP data to isolate stages of information processing associated with sensory registration (20-50 Hz; gamma band) and selective attention (0-20 Hz; low-frequency band). RESULTS: Compared to the non-psychiatric control group, patients with bipolar disorder exhibited reduced S1 response magnitudes for the conventional P50 peak-picking and low-frequency response analyses. A bipolar subgroup effect suggested that the attenuated S1 magnitudes from the P50 peak-picking and low-frequency analyses were largely attributable to patients without a history of psychosis. CONCLUSIONS: The analysis of distinct frequency bands of the auditory-evoked response elicited during the dual-click procedure allowed further specification of the nature of auditory sensory processing and gating deficits in bipolar disorder with or without a history of psychosis. The observed S1 effects in the low-frequency band suggest selective attention deficits in bipolar patients, especially those patients without a history of psychosis, which may reflect a diminished capacity to selectively attend to salient stimuli as opposed to impairments of inhibitory sensory processes.

Visual event-related potentials in schizotypal personality disorder and schizophrenia.

Schizophrenia (SZ) occurs among a spectrum of disorders with similar characteristics, including schizotypal personality disorder (SPD). Visual processing disturbances have been reported in both disorders, but it is not yet clear which processes are disturbed in both SZ and SPD, suggestive of a common endophenotype, and which appear only in SZ. In order to address this question, the authors evaluated visual event-related potentials (ERPs) elicited during a line-orientation discrimination task in control, SPD, and SZ participants. Visual ERPs allow specification of both the time course and physiological correlates of visual perception and cognition. SZ patients had smaller P100 and P300a amplitudes and prolonged P300b latency compared to the control group. SZ patients also had smaller N160, N200, P300a, and P300b amplitudes compared to the SPD group. SPD participants did not differ from control participants on any ERP measure. These data documented pervasive abnormalities in visual perception and attention in SZ but not in SPD, suggesting that these visual ERP disturbances may not represent a common endophenotype.

Event related brain potential evidence for preserved attentional set switching in schizophrenia.

Pervasive deficits of attention and set switching have been reported in schizophrenia, prompting efforts to identify the information processing mechanisms associated with these deficits. Recent evidence suggests that set switching may be intact in schizophrenia when the task switch requires only a change in the relevance of perceptual dimensions (e.g., attentional set switches) but decision-to-response mappings (intentional set) are maintained across trials in a cued task switching procedure. The goal of the present research was to replicate this finding and to test its direct corollary, which is the unconventional prediction that individuals with schizophrenia will evidence an intact, switch-sensitive P3(b) brain response to cued switches of attentional set. This prediction was tested in a group of 20 individuals with schizophrenia and 20 healthy comparison participants using event-related brain potential methodology and a cued task-switching task. Attentional set switching costs were equivalent between the two groups despite a set maintenance deficit in schizophrenia. Moreover, a posterior-parietal P3(b) component of the ERP was found to be equally sensitive to attentional set switching in schizophrenia and comparison groups, indicating a "healthy" brain response to switches of attentional set in schizophrenia. These results suggest that the dynamic control of attentional set may be preserved in schizophrenia and that previously reported executive deficits may be specific to the control of intentional task set and to deficits of task set maintenance.

Switch and maintenance of task set in schizophrenia.

Task set maintenance and switching deficits are robust in schizophrenia. However, little is known about how these constructs are related to one another. The development of an improved understanding of set switching and maintenance deficits in schizophrenia requires that these constructs be explicated in terms of elementary cognitive processes rather than grouped into broad psychological concepts like executive functioning. A relevant dichotomy has been proposed in which sensory and perceptual ("attentional") processes are distinguished from decisional ("intentional") processes in task maintenance and switching; however, the contributions these processes make to performance deficits in schizophrenia is not known. In the present study, 30 participants with schizophrenia and 27 healthy comparisons completed a cued attentional set switching task. In addition to analyses of mean response times, the contributions of attentional and intentional processes to task performance were estimated using an ex-Gaussian distributional analysis. Schizophrenia was associated with a set maintenance deficit that was accounted for by an attentional, rather than intentional, dysfunction. Both groups showed significant switch costs that could be attributed to attentional processes, but there was no evidence for an attentional set switching deficit in schizophrenia. The findings suggest that set switching and set maintenance may reflect distinct cognitive deficits in schizophrenia and that they may be associated with unique information processing mechanisms.

Evaluation of a clinically practical, ERP-based neurometric battery: Application to age-related changes in brain function.

OBJECTIVE: Event-related potentials (ERPs) show promise as markers of neurocognitive dysfunction, but conventional recording procedures render measurement of many ERP-based neurometrics clinically impractical. The purpose of this work was (a) to develop a brief neurometric battery capable of eliciting a broad profile of ERPs in a single, clinically practical recording session, and (b) to evaluate the sensitivity of this neurometric profile to age-related changes in brain function. METHODS: Nested auditory stimuli were interleaved with visual stimuli to create a 20-min battery designed to elicit at least eight ERP components representing multiple sensory, perceptual, and cognitive processes (Frequency & Gap MMN, P50, P3, vMMN, C1, N2pc, and ERN). Data were recorded from 21 younger and 21 high-functioning older adults. RESULTS: Significant multivariate differences were observed between ERP profiles of younger and older adults. Metrics derived from ERP profiles could be used to classify individuals into age groups with a jackknifed classification accuracy of 78.6%. CONCLUSIONS: Results support the utility of this design for neurometric profiling in clinical settings. SIGNIFICANCE: This study demonstrates a method for measuring a broad profile of ERP-based neurometrics in a single, brief recording session. These markers may be used individually or in combination to characterize/classify patterns of sensory and/or perceptual brain function in clinical populations.

Contributions of subtype and spectral frequency analyses to the study of P50 ERP amplitude and suppression in schizophrenia.

BACKGROUND: Poor suppression of P50 event-related potential (ERP) amplitudes to paired-click stimuli may indicate genetic liability for schizophrenia and weak "sensory gating." Evidence suggests, however, that P50 amplitude is selectively impaired in nonparanoid, but not paranoid, schizophrenia subtypes. Furthermore, paired-click suppression can appear deficient in schizophrenia due to smaller evoked responses to the first stimulus (S1), rather than larger, less effectively "gated" responses to the second (S2). Finally, the P50 ERP is comprised of activity from at least two frequency components that may be distinctly impaired: the gamma band, associated with sensory registration, and the low frequency response, associated with attention/encoding processes. P50 and related frequency subcomponents were examined as a function of illness subtype to further integrate these concepts. METHOD: The standard paired-click paradigm was administered to 38 schizophrenia (27 paranoid, 11 nonparanoid) and 38 age-matched healthy control participants. P50 amplitudes and spectral power of gamma band (GBR; 20-50 Hz) and low frequency (LFR; 1-20 Hz) responses were analyzed. RESULTS: P50 analyses revealed smaller S1 amplitude and normal S2 in schizophrenia participants collectively, but no differentiation of schizophrenia subtypes. Spectral analyses revealed smaller magnitude S1 and normal S2 responses in schizophrenia across both the GBR and LFR. The LFR, but not GBR, was found to distinguish nonparanoid from control groups, while paranoid participants evidenced no impairment in either frequency domain. LFR amplitude values correlated with clinical ratings of cognitive symptomatology. CONCLUSIONS: ERP deficits in the dual-click paradigm were specific to S1 amplitudes and most prominent in the low frequency response. These results replicate previous findings and extend their relevance to schizophrenia subtype distinctions. Implications for the recurrent inhibition model of sensory gating are discussed.

The effects of age on the neural correlates of feedback processing in a naturalistic gambling game.

We examined age-related differences in the spatiotemporal distribution of event-related brain potentials (ERPs) related to feedback processing in a virtual blackjack game. The behavioral data revealed that older adults were less risk seeking than younger adults both within and across trials. Age-related differences were observed in the amplitude of several ERP components (P2-FN-P3a, P3a, slow wave activity) related to feedback processing. These components were localized to the anterior and posterior cingulate, the occipital cortex, and the inferior and medial frontal cortices. The effects of aging on the ERPs ranged from 200-2,000 ms after feedback onset. Our findings indicate that aging affects the activity of a distributed neural network that underpins processing the valence and motivational significance of feedback related to risky decisions.

The role of encoding and attention in facial emotion memory: an EEG investigation.

Facial expressions are encoded via sensory mechanisms, but meaning extraction and salience of these expressions involve cognitive functions. We investigated the time course of sensory encoding and subsequent maintenance in memory via EEG. Twenty-nine healthy participants completed a facial emotion delayed match-to-sample task. P100, N170 and N250 ERPs were measured in response to the first stimulus, and evoked theta power (4-7Hz) was measured during the delay interval. Negative facial expressions produced larger N170 amplitudes and greater theta power early in the delay. N170 amplitude correlated with theta power, however larger N170 amplitude coupled with greater theta power only predicted behavioural performance for one emotion condition (very happy) out of six tested (see Supplemental Data). These findings indicate that the N170 ERP may be sensitive to emotional facial expressions when task demands require encoding and retention of this information. Furthermore, sustained theta activity may represent continued attentional processing that supports short-term memory, especially of negative facial stimuli. Further study is needed to investigate the potential influence of these measures, and their interaction, on behavioural performance.

The scientific study of inspiration in the creative process: challenges and opportunities.

Inspiration is a motivational state that compels individuals to bring ideas into fruition. Creators have long argued that inspiration is important to the creative process, but until recently, scientists have not investigated this claim. In this article, we review challenges to the study of creative inspiration, as well as solutions to these challenges afforded by theoretical and empirical work on inspiration over the past decade. First, we discuss the problem of definitional ambiguity, which has been addressed through an integrative process of construct conceptualization. Second, we discuss the challenge of how to operationalize inspiration. This challenge has been overcome by the development and validation of the Inspiration Scale (IS), which may be used to assess trait or state inspiration. Third, we address ambiguity regarding how inspiration differs from related concepts (creativity, insight, positive affect) by discussing discriminant validity. Next, we discuss the preconception that inspiration is less important than "perspiration" (effort), and we review empirical evidence that inspiration and effort both play important-but different-roles in the creative process. Finally, with many challenges overcome, we argue that the foundation is now set for a new generation of research focused on neural underpinnings. We discuss potential challenges to and opportunities for the neuroscientific study of inspiration. A better understanding of the biological basis of inspiration will illuminate the process through which creative ideas "fire the soul," such that individuals are compelled to transform ideas into products and solutions that may benefit society.

The neural correlates of temporal judgments in the duration bisection task.

Decision processes related to interval timing are commonly examined using the duration bisection procedure-a well-established timekeeping task in which participants make judgments about whether a series of "probes" are closer in duration to a "short" anchor duration or a "long" anchor duration. The specific information used during bisection categorization has been a subject of debate. Recent research involving the Contingent Negative Variation (CNV) suggests that the "short" anchor duration and a value near the geometric mean (GM) of the short and long anchors are among the critical pieces of information used during bisection categorization judgements. The present study examined a corollary of this claim, that memory comparison and decision-making processes related to the temporal judgments are completed prior to probe offset when probe durations are perceived to be "long;" testing the hypotheses that (1) response times would be significantly longer for "short" relative to "long" categorizations and that (2) there would be significant differences in ERPs time-locked to probe offset between probes judged to be "short" and "long." Both of these predictions were realized in the results, providing strong support for the assertion that a value near the GM-likely the point of subjective equality (PSE)-is among the critical information used during bisection categorization judgments.

Dissociating stimulus-set and response-set in the context of task-set switching.

The primary aim of the present research was to determine how stimulus-set and response-set components of task-set contribute to switch costs and conflict processing. Three experiments are described wherein participants completed an explicitly cued task-switching procedure. Experiment 1 established that task switches requiring a reconfiguration of both stimulus- and response-set incurred larger residual switch costs than task switches requiring the reconfiguration of stimulus-set alone. Between-task interference was also drastically reduced for response-set conflict compared with stimulus-set conflict. A second experiment replicated these findings and demonstrated that stimulus- and response-conflict have dissociable effects on the "decision time" and "motor time" components of total response time. Finally, a third experiment replicated Experiment 2 and demonstrated that the stimulus- and response- components of task switching and conflict processing elicit dissociable neural activity as evidence by event-related brain potentials.