Response inhibition in psychopathy: the frontal N2 and P3

Stroke affects a large number of people, especially in developed countries, but treatment options are limited. Over the years, it has become clear that nitric oxide (NO) plays a major role in this pathology and that treatments that either reduce or increase NO presence may provide an alternative route for reducing the sequelae of brain ischemia. The NO donor LA 419 previously has been shown to protect the brain tissue from ischemic damage in an experimental model of global brain ischemia. Here we study whether this holds true for focal ischemia, a condition closer to the more common form of human stroke. Ischemia was induced in rats by a stereotaxic injection of endothelin-1, a potent vasoconstrictor, in the striatum. Seven days after the injection, magnetic resonance imaging (MRI) found a significant elevation in apparent diffusion coefficient (ADC) in the injected striatum of untreated rats, due to ischemia-induced vascular edema. Animals that received LA 419 prior to injection with endothelin-1 showed an ADC undistinguishable from the contralateral striatum or from the striatum of rats not treated with LA 419. In addition, immunohistochemistry with antibodies against neuronal nitric oxide synthase (nNOS), inducible NOS (iNOS), and nitrotyrosine showed a marked increase in the expression of these markers of NO production following ischemic treatment that was dampened by treatment with LA 419. In summary, our results clearly show that the NO donor LA 419 may be a useful compound for the prevention and/or treatment of focal brain ischemia.     

Reconciling discrepant findings for P3 brain response in criminal psychopathy through reference to the concept of externalizing proneness

We sought to address inconsistencies in the literature on amplitude of P3 brain potential response in offenders diagnosed with psychopathy. These inconsistencies contrast with the reliable finding of reduced P3 in relation to externalizing tendencies, which overlap with impulsive‐antisocial features of psychopathy, as distinguished from the affective‐interpersonal features. Employing a sample of incarcerated male offenders (N = 154) who completed the Psychopathy Checklist–Revised along with a three‐stimulus visual oddball task, we tested the hypothesis that impulsive‐antisocial features of psychopathy would selectively exhibit an inverse relationship with P3 amplitude. Clear support for this hypothesis was obtained. Our findings clarify the discrepant findings regarding psychopathy and P3, and establish P3 as a neurophysiological point of contact between psychopathy and externalizing proneness from the broader psychopathology literature.     

It's not too late: The onset of the frontocentral P3 indexes successful response inhibition in the stop‐signal paradigm

The frontocentral P3 event‐related potential has been proposed as a neural marker of response inhibition. However, this association is disputed: some argue that P3 latency is too late relative to the timing of action stopping (stop‐signal reaction time; SSRT) to index response inhibition. We tested whether P3 onset latency is a marker of response inhibition, and whether it coincides with the timing predicted by neurocomputational models. We measured EEG in 62 participants during the stop‐signal task, and used independent component analysis and permutation statistics to measure the P3 onset in each participant. We show that P3 onset latency is shorter when stopping is successful, that it is highly correlated with SSRT, and that it coincides with the purported timing of the inhibition process (towards the end of SSRT). These results demonstrate the utility of P3 onset latency as a noninvasive, temporally precise neural marker of the response inhibition process.     

Your brain on bikes: P3, MMN/N2b,and baseline noise while pedaling a stationary bike

Increasingly, there is a trend to measure brain activity in more ecologically realistic scenarios. Normally, the confines of the laboratory and sedentary tasks mitigate sources of electrical noise on EEG measurement. Moving EEG outside of the lab requires understanding of the impact of complex movements and activities on traditional EEG and ERP measures. Here, we recorded EEG with active electrodes while participants were either riding or sitting on a stationary bike in an electrical and sound‐attenuated chamber in the lab. Participants performed an auditory oddball task, pressing a button when they detected rare target tones in a series of standard frequent tones. We quantified both the levels of spectral, single‐trial baseline, and ERP baseline noise, as well as classic MMN/N2b and P3 ERP components measured during both biking and sitting still. We observed slight increases in posterior high frequency noise in the spectra, and increased noise in the baseline period during biking. However, morphologically and topographically similar MMN/N2b and P3 components were measured reliably while both biking and sitting. A quantification of the power to reliably measure ERPs as a function of the number of trials revealed slight increases in the number of trials needed during biking to achieve the same level of power. Taken in sum, our results confirm that classic ERPs can be measured reliably during biking activities in the lab. Future directions will employ these techniques outside the lab in ecologically valid situations.     

Emotion processing in Psychopathy Checklist — assessed psychopathy: A review of the literature

Deficient emotional experience is recognized as one of the central features of psychopathy and an impressive body of empirical findings regarding emotion processing in psychopathy has amassed over the past several decades, resulting in two broad theoretical perspectives. The general emotional deficit perspective postulates a globally reduced capacity for emotional experience and processing across the emotional spectrum. In contrast, according to the specific emotional deficit perspective, psychopathy is associated with abnormal experience of only specific types of emotion; several distinct hypotheses have been proposed under this latter perspective. We systematically and critically review findings from peer-reviewed research of emotion processing in psychopathy in relation to the two theoretical perspectives. In general, findings suggest that, compared to controls, psychopaths exhibit behavioral, psychophysiologic, and regional brain activation anomalies when processing emotion, but their ratings of self-arousal and stimulus valence/intensity do not differ from controls. However, when behavioral findings are examined separately by emotion type, the overall pattern of findings is not clearly consistent with any of the dominant theoretical perspectives of emotion processing in psychopathy. We summarize the current state of the field, including consistencies and inconsistencies in the literature, offer alternative explanations for the findings, and outline directions for future research.     

Contextual modulation of oculomotor control reflected in N2 and saccade reaction time distributions

Avoiding reflexive saccades triggered by salient yet task-irrelevant stimuli requires the engagement of control processes that inhibit attention toward irrelevant objects and prevent reflex-like oculomotor action. In the current study participants made saccades to visual targets to the left and right of fixation as directed by target appearance. A distractor could either be presented in the same (congruent trials) or the opposite hemifield (incongruent trials) as the target. Trial context was manipulated, creating risky (mostly incongruent blocks), safe (mostly congruent blocks), or neutral conditions. Electroencephalogram was measured to examine if any contextual modulations would be reflected in the N2 peak frequently associated with performance monitoring. The results are discussed within the framework of dual mechanisms of cognitive control and suggest that a high-risk context facilitates avoidance of capture, lessening the need for reactive control.     

诈骗犯、暴力犯的黑暗三人格与创造力及标新立异的关系

目的:探讨诈骗犯和暴力犯的黑暗三人格、创造力及标新立异的特点及差异,并探究黑暗三人格对创造性和标新立异的预测作用。方法:在北京市某监狱选取了108名成年男性诈骗犯和142名成年男性暴力犯,施测高夫创造力量表、短式黑暗三联征量表和标新立异量表。结果:(1)两类罪犯的马基雅维利主义、精神病态、自恋、黑暗三人格总分均与标新立异显著正相关(r=0.389,0.616,0.374,0.614;P0.01),马基雅维利主义、自恋、黑暗三人格总分与创造力显著正相关(r=0.151,0.398,0.251;P0.05或P0.01),创造力与标新立异显著正相关(r=0.137,P0.05);(2)回归分析表明,马基雅维利主义、精神病态、自恋显著正向预测标新立异(B=0.192,B=0.775,B=0.297;P0.001),仅自恋因子可以显著正向预测创造力(B=0.347,P0.001);(3)诈骗犯的创造力显著高于暴力犯(t=3.53,P0.001),精神病态(t=-1.86,P=0.064)和标新立异程度(t=-1.75,P=0.087)低于暴力犯,均达到边缘显著水平。结论:黑暗三人格与创造力和标新立异关系密切,不同犯罪类型的罪犯具有不同的人格和特质特点。     

Effects of stop-signal modality on the N2/P3 complex elicited in the stop-signal paradigm

The principal aim of the present study was to clarify how stop-signal modality affected the speed and efficacy of stopping, using ERP components as converging measures of stop processes. Both performance and ERP latency findings suggested faster processing of stop signals in the auditory than visual version of the stop task. The effects of successful versus unsuccessful stopping on the amplitude and topography of N2/P3 components elicited by the stop signals appeared to be largely independent of the modality of the stop signals. Stop signals elicited a fronto-central N2 that was much larger on unsuccessful than successful stop trials in stimulus-locked waveforms. N2 was followed by a P3 component that showed a fronto-central distribution on successful stop trials. P3 elicited on unsuccessful stop trials showed a posterior-parietal focus, but this topography was manifested more clearly in response-locked than stimulus-locked waveforms. A dipole source analyses confirmed these topographical differences of P3, and further showed that the location of the corresponding dipoles remained largely identical across the visual and auditory versions of the stop-signal task. Taken together, the present findings support the suggestion that ERP components in the stop task reflect endogenous aspects of stop-signal processing, such as effective inhibition of responses on successful stop trials and detection of errors on failed inhibition trials.     

P50, N100, and P200 sensory gating: Relationships with behavioral inhibition, attention, and working memory

P50, N100, and P200 auditory sensory gating could reflect mechanisms involved in protecting higher-order cognitive functions, suggesting relationships between sensory gating and cognition. This hypothesis was tested in 56 healthy adults who were administered the paired-click paradigm and two adaptations of the continuous performance test (Immediate/Delayed Memory Task, IMT/DMT). Stronger P50 gating correlated with fewer commission errors and prolonged reaction times on the DMT. Stronger N100 and P200 gating correlated with better discriminability on the DMT. Finally, prolonged P200 latency related to better discriminability on the IMT. These findings suggest that P50, N100, and P200 gating could be involved in protecting cognition by affecting response bias, behavioral inhibition, working memory, or attention.     

Beware misleading cues: perceptual similarity modulates the N2/P3 complex

Event-related potentials were used to investigate neural processes relating perceptual similarity to action control. To assess whether perceptual overlap among targets and nontargets would modulate the N2/P3 complex, the present study used multiple nontarget categories varying in their targetlike characteristics. Participants made one (relatively rare) response to a low-probability stimulus (target), and they made a different (relatively common) response to all other stimuli (nontargets). The critical nontarget categories had equivalent probability (.10) but varied in their targetlike characteristics. Supporting the N2 component as sensitive to the strength of conflicting action imperatives, perceptual overlap among targets and nontargets elicited a prominent N2. In contrast, amplitude of the P3 component appeared most sensitive to the extent of cognitive processing needed for categorization.     

N1 and P2 to words and wordlike stimuli in late elementary school children and adults

In an investigation of the development of fine‐tuning for word processing across the late elementary school years as indexed by the posterior N1 and P2 components of the ERP waveform, third, fourth, and fifth graders and a comparison group of adults viewed words, pseudowords, nonpronounceable letter strings, and false font strings in a semantic categorization task. In adults, N1 was larger to and P2 was later to words as compared to pseudowords, a finely tuned effect of lexicality reflecting specialization for word processing. In contrast, in each group of children, N1 was larger to letter strings than false font strings and P2 was larger to false font strings than letter strings, reflecting coarse encoding for orthography. In regression analyses, scores on standardized behavioral test measures of orthographic knowledge, decoding skill, and fluency predicted N1 amplitude; these effects were not significant with age included as a separate predictor. None of the behavioral scores, in models including or not including age, predicted P2 amplitude. In direct comparisons between groups, there were multiple differences between the child and adult groups for both N1 and P2 amplitude effects, and only a single significant difference between two child groups. Overall, the findings suggest a lengthy developmental time course for the fine‐tuning of early word processing as indexed by N1 and P2.     

Genes mediate the association between P3 amplitude and externalizing disorders

Reduced P3 amplitude has been consistently linked to a spectrum of externalizing disorders. Utilizing data from a large sample of adolescent male twins (N=1196), we used biometric modeling to assess the genetic and environmental contributions to the association between reduced P3 amplitude and a general vulnerability to externalizing disorders. Externalizing vulnerability was indexed by a composite of symptoms of conduct disorder, adult antisocial behavior, and alcohol, nicotine, and drug dependence. The sample included two independent age cohorts, providing an internal replication of the findings. For the best-fitting model, genetic influences alone accounted for the association between P3 amplitude and externalizing disorders, with an estimated genetic correlation of r(g)=-.22. Results replicated across the two age cohorts and demonstrate that reduced P3 amplitude is a marker of the biological vulnerability to externalizing disorders.     

The P3b and P600(s): Positive contributions to language comprehension

Since its discovery in the 1960s, the P300 has been contributing both directly and indirectly to language research. Perhaps most notably, it has been suggested that the P600, an ERP component that was first characterized in the context of syntactic processing, could be a variant of the P3b subcomponent of the P300. Here, we review studies on both sides of the debate. We also review the “semantic P600,” a positivity with a similar time course and distribution to the P600 seen for syntactic manipulations but that is obtained in response to some types of semantic anomalies. Because most current theories of the P600 try to account for both the syntactic and the semantic variant, linking the syntactic P600 to the P3b might also imply a similar link for the semantic P600. However, we describe emerging research in our lab that casts doubt on the idea that the syntactic P600 and the semantic P600 are the same effect. We argue that grouping ERP responses primarily by domain (language vs. nonlanguage) is likely to be misleading and suggest alternative ways of determining whether ERP effects reflect similar or different processing mechanisms.     

The role of trait impulsivity in response inhibition: Event-related potentials in a stop-signal task

The study examined the relation between self-reported impulsivity and inhibitory control in normal individuals. We compared stopping performance and neural correlates of stopping on stop-signal task between participants who scored in the top (n = 12) and bottom 25% (n = 12) on Impulsivity Scale from a sample of 305 male adults. Participants scoring high on impulsivity did not show impaired inhibitory control. However, it seems that the high impulsive tended to make more errors of commission and omission. Enhanced N1 amplitudes were found in successful than failed inhibition trials. The high impulsive group had smaller P3 amplitude than the low impulsive group. It appears that the high impulsive group may have a less efficient inhibitory control. Impulsivity Scale non-planning impulsiveness score and inattention score of Adult ADHD Self-Report Scale (ASRS) were negatively correlated with P3 amplitudes on successful inhibition trails, suggesting that impulsivity could have the potential influence on inhibitory control.     

ERP to chess stimuli reveal expert‐novice differences in the amplitudes of N2 and P3 components

ERP experiments were conducted to analyze the underlying neural events when chess players make simple judgments of a board position. Fourteen expert players and 14 age‐matched novices viewed, for each of four tasks, 128 unique positions on a mini (4 × 4) chess board each presented for 0.5 s. The tasks were to respond: (a) if white king was in check, (b) if black knight was present, (c) if white king was not in check, and (d) if no black knight was present. Experts showed an enhanced N2 with check targets and a larger P3 with knight targets, relative to novices. Expert‐novice differences in posterior N2 began as early as 240 ms on check‐related searches. Results were consistent with the view that prolonged N2 components reflect matching of current perceptual input to memory, and thus are sensitive to experts' superior pattern recognition and memory retrieval of chunks.     

General proactive interference and the N450 response

Strategic repetition of verbal stimuli can effectively produce proactive interference (PI) effects in the Sternberg working memory task. Unique fronto-cortical activation to PI-eliciting letter probes has been interpreted as reflecting brain responses to PI. However, the use of only a small set of stimuli (e.g., letters and digits) requires constant repetition of stimuli in both PI and baseline trials, potentially creating a general PI effect in all conditions. We used event-related potentials to examine general PI effects by contrasting the interference-related frontal N450 response in two Sternberg tasks using a small versus large set size. We found that the N450 response differed significantly from baseline during the small set-size task only for response-conflict PI trials but not when PI was created solely from stimulus repetition. During the large set-size task N450 responses in both the familiarity-based and response-conflict PI conditions differed from baseline but not from each other. We conclude that the general stimulus repetition inherent in small set-size conditions can mask effects of familiarity-based PI and complicate the interpretation of any associated neural response.     

Contingent Negative Variation, P3 Evoked Potentials, and Antisocial Behavior

While initial investigations have found significantly lower contingent negative variation (CNV) amplitudes in adult, institutionalised antisocial groups, others have found either no group differences or significantly higher amplitudes. This study attempts to circumvent some methodological and conceptual problems in previous stud its by assessing CNV in a classical forewarned reaction time experiment in two samples of non-institutionalised normal adolescents where behavioral ratings and self-report measures were used to define Antisocial and Pro social groups. A trend toward higher P3 amplitudes to the warning stimulus (SI) observed in a previous study was also investigated by recording evoked potentials to SI. Results indicated no significant group differences in CNV and Nl amplitudes, but a significantly larger P3 amplitude in the Antisocial group in both subject samples. This latter result was viewed as consistent with Jutai and Hare's (1983) finding that psychopathic anti socials have a heightened capacity to attend to events of immediate interest.     

The independency of the Bereitschaftspotential from previous stimulus‐locked P3 in visuomotor response tasks

The Bereitschaftspotential (BP) and the P3 are well‐known ERPs usually observed during self‐paced and externally triggered tasks. Recently, the BP was also detected in externally triggered tasks before stimulus onset. However, doubts have been raised about the authenticity of the BP in these tasks due to possible overlaps with the previous trial P3 (hereinafter s‐1 P3). Here, we aim to test the authenticity of the BP in externally triggered tasks by comparing ERPs obtained during two visuomotor response tasks with different interstimulus intervals (ISIs) allowing (short‐ISI; 1,000–2,000 ms) or not (long‐ISI; 2,000–4,000 ms) P3‐BP overlaps. In line with previous research, we hypothesize that BP and the s‐1 P3 contribute independently to the scalp‐detected activities during these tasks. ERPs were recorded from 14 healthy participants during the short‐ISI and long‐ISI visuomotor response tasks. Amplitudes and latencies of pre‐ (BP and pN) and poststimulus ERP components (P1, pN1, pP1, N1, pP2, dpP2, N2, P3) were compared between conditions. No effect of ISI was found on the amplitude of any pre‐ and poststimulus components. In contrast, longer ISI is associated with earlier onsets of the BP and pN components. In visuomotor response tasks, the BP is independent from the P3 elicited by the previous trial (s‐1 P3), even using relatively short ISI. Since the different ISIs did not affect the amplitude of the BP and the P3 components, we conclude that also a short ISI can be adopted safely and conveniently to keep a reasonable duration of the overall experiment.     

P3 event-related potential impairments in antisocial and psychopathic individuals: A meta-analysis

Prior findings on P3 event-related potential deficits in antisocial populations are mixed and it has been suggested that these abnormalities may not apply to psychopaths. A meta-analysis of 38 studies (total N = 2616) was conducted to investigate the relationship of P3 measures to antisocial behavior. Reduced P3 amplitudes (d = 0.252, p < .001) and longer P3 latencies (d = 0.130, p = .019) were significantly associated with antisocial behavior across all electrode sites, and when using both normal and non-normal control groups. A significant moderating effect of electrode site indicated longer latencies at Fz but not Pz. Compared to non-psychopathic offenders, psychopathic offenders showed P3 amplitudes impairments in standard oddball tasks, but not other tasks. Findings suggest that reduced P3 amplitudes and prolonged P3 latencies may reflect inefficient deployment of neural resources in processing cognitive task-relevant information in individuals characterized with generic antisocial behavior (i.e., aggression, antisocial personality disorder, conduct disorder/oppositional-defiant disorder, and psychopathy), whereas this association in psychopaths may be moderated by the type of tasks.     

Wearing a bike helmet leads to less cognitive control,revealed by lower frontal midline theta power and risk indifference

A recent study claims that participants wearing a bike helmet behave riskier in a computer‐based risk task compared to control participants without a bike helmet. We hypothesized that wearing a bike helmet reduces cognitive control over risky behavior. To test our hypothesis, we recorded participants' EEG brain responses while they played a risk game developed in our laboratory. Previously, we found that, in this risk game, anxious participants showed greater levels of cognitive control as revealed by greater frontal midline theta power, which was associated with less risky decisions. Here, we predicted that cognitive control would be reduced in the helmet group, indicated by reduced frontal midline theta power, and that this group would prefer riskier options in the risk game. In line with our hypothesis, we found that participants in the helmet group showed significantly lower frontal midline theta power than participants in the control group, indicating less cognitive control. We did not replicate the finding of generally riskier behavior in the helmet group. Instead, we found that participants chose the riskier option in about half of trials, no matter how risky the other option was. Our results suggest that wearing a bike helmet reduces cognitive control, as revealed by reduced frontal midline theta power, leading to risk indifference when evaluating potential behaviors.