Early sensory-perceptual processing deficits for affectively valenced inputs are more pronounced in schizophrenia patients with a history of violence than in their non-violent peers

Predicting forensic inpatient violence with odor identification and neuropsychological measures of impulsivity: A preliminary study

Although most persons with a schizophrenia-spectrum disorder are not aggressive, a minority is at higher risks to commit violent acts, especially in forensic settings. The first goal of this study was to assess inpatients in a maximum-security hospital with a self-report questionnaire, neuropsychological tests of behavioral impulsivity/attentional capacities and olfactory functions to determine the strength of association between these measures. A secondary objective was to assess the predictive value of these measures for the commission of violent acts within the institution. Sixty-two male inpatients were evaluated with the neuropsychological battery. As expected, self-report assessment of trait impulsivity (questionnaire) did not significantly correlate with behavioral measures of state impulsivity. In addition, neuropsychological measures of impulsivity and attention were significantly associated with odor identification capacities. Finally, attentional deficits (but not impulsivity) and odor identification were both significant and independent predictors of institutional violence. Neuropsychological assessments and odor functions might help predicting (and explaining) institutional violence committed in forensic settings.

Prosodic deficits and interpersonal difficulties in patients with schizophrenia

The present study examines the use of receptive emotional and linguistic prosody in patients with schizophrenia; particularly, its aim was to evaluate the type and number of errors made when comprehending the emotions and modes implied by meaningless utterances. Seventy-eight participants were enrolled to the study, i.e. two groups (patients with schizophrenia and healthy controls) consisting of 39 subjects. The severity of illness was evaluated with the Positive and Negative Syndrome Scale; comprehension of emotional and linguistic prosody was assessed by the subtests of the Polish Version of the Right Hemisphere Language Battery. Neither emotional nor linguistic prosody comprehension both correlated with schizophrenia symptoms. The study group experienced more difficulties in distinguishing between happiness and anger, and were more likely to misunderstand imperative utterances, confusing them with interrogative or affirmative ones. Such impairments are significant as they may affect the ability to form and sustain relationships with other people, achieve success in the work environment, and integrate in the community. They may also be a trait mark of the illness independent of psychotic symptoms. Further research is needed to translate this knowledge into meaningful and therapeutic interventions to improve quality of life, both for affected individuals and for their communication partners.

Assessing combinatorial effects of HIV infection and former cocaine dependence on cognitive control processes: A high-density electrical mapping study of response inhibition

Stimulant drug use in HIV + patients is associated with poor personal and public health outcomes, including high-risk sexual behavior and faster progression from HIV to AIDS. Inhibitory control--the ability to withhold a thought, feeling, or action--is a central construct involved in the minimization of risk-taking behaviors. Recent neuroimaging and behavioral evidence indicate normalization of inhibitory control processes in former cocaine users as a function of the duration of drug abstinence, but it is unknown whether this recovery trajectory persists in former users with comorbid HIV. Here, we investigate the neural correlates of inhibitory control in 103 human subjects using high-density EEG recording as participants performed a Go/NoGo response inhibition task. Four groups of participants were recruited, varying on HIV and cocaine-dependence status. Electrophysiological responses to successful inhibitions and behavioral task performance were compared among groups. Results indicate persistent behavioral and neurophysiological impairment in HIV+ patients' response inhibition despite current abstinence from cocaine. Analysis of task performance showed that HIV+ abstinent cocaine-dependent participants demonstrate the lowest performance of all groups across all metrics of task accuracy. Planned comparisons of electrophysiological components revealed a main effect of scalp site and an interaction between HIV-status and scalp site on N2 amplitudes during successful inhibitions. Analysis of the P3 time region showed a main effect of scalp site and an interaction between HIV-status and cocaine dependence. These results suggest synergistic alterations in the neurophysiology of response inhibition and indicate that abstinence-related recovery of inhibitory control may be attenuated in patients with HIV.

White Matter Correlates of Hostility and Aggression in the Visuospatial Function Network in Patients With Schizophrenia

Background: Violent acts in patients with schizophrenia are often associated with their hostility and aggression levels. Poor visuospatial processing has been suggested as a possible risk factor of violence in schizophrenia. However, studies investigating the relationship between hostility, aggression, and the visuospatial function have been lacking. Here, we aimed to investigate brain dysconnectivity associated with hostility and aggression in schizophrenia, particularly focusing on the visuospatial function network. Methods: Eighty-eight participants with schizophrenia and 42 healthy controls were enrolled. The visuospatial function network regions of interest were analyzed using Tract-Based Spatial Statistics. The hostility item from the Positive and Negative Syndrome Scale (PANSS), aggressive, and agitated behavior item from the Scale for the Assessment of Positive Symptoms (SAPS), and the Rey Complex Figure Test (R-CFT) were measured. Results: Among the participants with schizophrenia, the SAPS aggressive and agitated behavior scores were significantly correlated with fractional anisotropies (FAs) of the white matter regions in the splenium of the corpus callosum (CC), left posterior thalamic radiations (PTR), and left posterior corona radiata (PCR). Exploratory correlational analysis revealed significant negative correlations between FAs of the splenium of the CC and R-CFT copy and immediate recall scores. In addition, three regions including CC, PTR, and PCR that significantly correlated with the aggression scores showed significant correlations with the total PANSS scores. Conclusion: Our main finding suggests that aggression of patients with schizophrenia may be associated with poor visuospatial ability and underlying white matter dysconnectivity. These may help enhance understanding aggression in patients with schizophrenia.

Atypical response inhibition and error processing in 22q11.2 Deletion Syndrome and schizophrenia: Towards neuromarkers of disease progression and risk

22q11.2 deletion syndrome (also known as DiGeorge syndrome or velo-cardio-facial syndrome) is characterized by increased vulnerability to neuropsychiatric symptoms, with approximately 30% of individuals with the deletion going on to develop schizophrenia. Clinically, deficits in executive function have been noted in this population, but the underlying neural processes are not well understood. Using a Go/No-Go response inhibition task in conjunction with high-density electrophysiological recordings (EEG), we sought to investigate the behavioral and neural dynamics of inhibition of a prepotent response (a critical component of executive function) in individuals with 22q11.2DS with and without psychotic symptoms, when compared to individuals with idiopathic schizophrenia and age-matched neurotypical controls. Twenty-eight participants diagnosed with 22q11.2DS (14-35 years old; 14 with at least one psychotic symptom), 15 individuals diagnosed with schizophrenia (18-63 years old) and two neurotypical control groups (one age-matched to the 22q11.2DS sample, the other age-matched to the schizophrenia sample) participated in this study. Analyses focused on the N2 and P3 no-go responses and error-related negativity (Ne) and positivity (Pe). Atypical inhibitory processing was shown behaviorally and by significantly reduced P3, Ne, and Pe responses in 22q11.2DS and schizophrenia. Interestingly, whereas P3 was only reduced in the presence of psychotic symptoms, Ne and Pe were equally reduced in schizophrenia and 22q11.2DS, regardless of the presence of symptoms. We argue that while P3 may be a marker of disease severity, Ne and Pe might be candidate markers of risk.

Attention deficit hyperactivity disorder: Last in, first out - delayed brain maturation with an accelerated decline?

While early neurodevelopmental processes during the emergence of ADHD in childhood received considerable attention, the neurobiological mechanisms that underlie the changes in ADHD in adulthood remain largely unaddressed. We wanted to delineate neurodevelopmental changes in adult ADHD using an electrophysiological measure, the fronto-central NoGo P3 event-related potential (ERP), which is an important neurophysiological index of brain functioning in ADHD, and biomarker for response inhibition and aging. ERPs were obtained from 45 ADHD and 41 healthy subjects using a 128-channel BioSemi recording-system, applying emotionally-valenced and neutral stimuli in a response inhibition task. Our results indicated that ADHD subjects manifested delayed developmental P3-trajectory in young-adulthood as compared to controls; they also showed P3 reduction across all emotional valences, and the reduction was most pronounced at younger ages. The differences in P3 diminished by mid-adulthood, and started to increase again at more advanced ages. Thus, similar to structural-MRI indices, developmental brain differences in the fronto-central NoGo P3 in ADHD largely normalize in young-adulthood. However, a reduction of P3 occurs again starting from mid-adulthood. As the fronto-central NoGo P3 reflects the functioning of the frontal areas (which show delayed maturation in ADHD), our findings are consistent with the ''last in, first out'' hypothesis, which refers to a mirroring pattern of brain development and aging, and posits that brain regions that develop relatively late degenerate relatively early with age. Thus, ADHD may not only be associated with delayed neurodevelopment, but also with a premature age-related deterioration, at least in some measures of electrophysiological functioning.

Mobile Brain/Body Imaging of cognitive-motor impairment in multiple sclerosis: Deriving EEG-based neuro-markers during a dual-task walking study

OBJECTIVE

Individuals with a diagnosis of multiple sclerosis (MS) often present with cognitive and motor deficits, and thus the ability to perform tasks that rely on both domains may be particularly impaired. Yet, dual-task walking studies yield mixed results. Individual variance in the ability to cope with brain insult and mobilize additional brain resources may contribute to mixed findings.

METHODS

To test this hypothesis, we acquired event-related potentials (ERP) in individuals with MS and healthy controls (HCs) performing a Go/NoGo task while sitting (i.e., single task) or walking (i.e., dual-task) and looked at the relationship between task related modulation of the brain response and performance.

RESULTS

On the Go/NoGo task the MS group showed dual-task costs when walking, whereas HCs showed a dual-task benefit. Further, whereas the HC group showed modulation of the brain response as a function of task load, this was not the case in the MS group. Analysis for the pooled sample revealed a positive correlation between load-related ERP effects and dual-task performance.

CONCLUSIONS

These data suggest a neurophysiological marker of cognitive-motor dysfunction in MS.

SIGNIFICANCE

Understanding neural processes underlying dual-task walking will help identify objective brain measurements of real-world issues and may improve assessment of MS.

Processing of Emotions in Speech in Forensic Patients With Schizophrenia: Impairments in Identification, Selective Attention, and Integration of Speech Channels

Individuals with schizophrenia show deficits in recognition of emotions which may increase the risk of violence. This study explored how forensic patients with schizophrenia process spoken emotion by: (a) identifying emotions expressed in prosodic and semantic content separately, (b) selectively attending to one speech channel while ignoring the other, and (c) integrating the prosodic and the semantic channels, compared to non-clinical controls. Twenty-one forensic patients with schizophrenia and 21 matched controls listened to sentences conveying four emotions (anger, happiness, sadness, and neutrality) presented in semantic or prosodic channels, in different combinations. They were asked to rate how much they agreed that the sentences conveyed a predefined emotion, focusing on one channel or on the sentence as a whole. Forensic patients with schizophrenia performed with intact identification and integration of spoken emotions, but their ratings indicated reduced discrimination, larger failures of selective attention, and under-ratings of negative emotions, compared to controls. This finding doesn't support previous reports of an inclination to interpret social situations in a negative way among individuals with schizophrenia. Finally, current results may guide rehabilitation approaches matched to the pattern of auditory emotional processing presented by forensic patients with schizophrenia, improving social interactions and quality of life.

Impaired mixed emotion processing in the right ventrolateral prefrontal cortex in schizophrenia: an fMRI study

BACKGROUND

Schizophrenia has a negative effect on the activity of the temporal and prefrontal cortices in the processing of emotional facial expressions. However no previous research focused on the evaluation of mixed emotions in schizophrenia, albeit they are frequently expressed in everyday situations and negative emotions are frequently expressed by mixed facial expressions.

METHODS

Altogether 37 subjects, 19 patients with schizophrenia and 18 healthy control subjects were enrolled in the study. The two study groups did not differ in age and education. The stimulus set consisted of 10 fearful (100%), 10 happy (100%), 10 mixed fear (70% fear and 30% happy) and 10 mixed happy facial expressions. During the fMRI acquisition pictures were presented in a randomized order and subjects had to categorize expressions by button press.

RESULTS

A decreased activation was found in the patient group during fear, mixed fear and mixed happy processing in the right ventrolateral prefrontal cortex (VLPFC) and the right anterior insula (RAI) at voxel and cluster level after familywise error correction. No difference was found between study groups in activations to happy facial condition. Patients with schizophrenia did not show a differential activation between mixed happy and happy facial expression similar to controls in the right dorsolateral prefrontal cortex (DLPFC).

CONCLUSIONS

Patients with schizophrenia showed decreased functioning in right prefrontal regions responsible for salience signaling and valence evaluation during emotion recognition. Our results indicate that fear and mixed happy/fear processing are impaired in schizophrenia, while happy facial expression processing is relatively intact.

Neuropsychology and emotion processing in violent individuals with antisocial personality disorder or schizophrenia: The same or different? A systematic review and meta-analysis

OBJECTIVES

To assess whether there are shared or divergent (a) cognitive and (b) emotion processing characteristics among violent individuals with antisocial personality disorder and/or schizophrenia, diagnoses which are commonly encountered at the interface of mental disorder and violence. Cognition and emotion processing are incorporated into models of violence, and thus an understanding of these characteristics within and between disorder groups may help inform future models and therapeutic targets.

METHODS

Relevant databases (OVID, Embase, PsycINFO) were searched to identify suitable literature. Meta-analyses comparing cognitive function in violent schizophrenia and antisocial personality disorder to healthy controls were conducted. Neuropsychological studies not comparing these groups to healthy controls, and emotion processing studies, were evaluated qualitatively.

RESULTS

Meta-analyses indicated lower IQ, memory and executive function in both violent schizophrenia and antisocial personality disorder groups compared to healthy controls. The degree of deficit was consistently larger in violent schizophrenia. Both antisocial personality disorder and violent schizophrenia groups had difficulties in aspects of facial affect recognition, although theory of mind results were less conclusive. Psychopathic traits related positively to experiential emotion deficits across the two disorders. Very few studies explored comorbid violent schizophrenia and antisocial personality disorder despite this being common in clinical practice.

CONCLUSION

There are qualitatively similar, but quantitatively different, neuropsychological and emotion processing deficits in violent individuals with schizophrenia and antisocial personality disorder which could be developed into transdiagnostic treatment targets for violent behaviour. Future research should aim to characterise specific subgroups of violent offenders, including those with comorbid diagnoses.

Neuroanatomical Abnormalities in Violent Individuals with and without a Diagnosis of Schizophrenia

Several structural brain abnormalities have been associated with aggression in patients with schizophrenia. However, little is known about shared and distinct abnormalities underlying aggression in these subjects and non-psychotic violent individuals. We applied a region-of-interest volumetric analysis of the amygdala, hippocampus, and thalamus bilaterally, as well as whole brain and ventricular volumes to investigate violent (n = 37) and non-violent chronic patients (n = 26) with schizophrenia, non-psychotic violent (n = 24) as well as healthy control subjects (n = 24). Shared and distinct volumetric abnormalities were probed by analysis of variance with the factors violence (non-violent versus violent) and diagnosis (non-psychotic versus psychotic), adjusted for substance abuse, age, academic achievement and negative psychotic symptoms. Patients showed elevated vCSF volume, smaller left hippocampus and smaller left thalamus volumes. This was particularly the case for non-violent individuals diagnosed with schizophrenia. Furthermore, patients had reduction in right thalamus size. With regard to left amygdala, we found an interaction between violence and diagnosis. More specifically, we report a double dissociation with smaller amygdala size linked to violence in non-psychotic individuals, while for psychotic patients smaller size was linked to non-violence. Importantly, the double dissociation appeared to be mostly driven by substance abuse. Overall, we found widespread morphometric abnormalities in subcortical regions in schizophrenia. No evidence for shared volumetric abnormalities in individuals with a history of violence was found. Finally, left amygdala abnormalities in non-psychotic violent individuals were largely accounted for by substance abuse. This might be an indication that the association between amygdala reduction and violence is mediated by substance abuse. Our results indicate the importance of structural abnormalities in aggressive individuals.

Deficits in attentional processing of fearful facial expressions in schizophrenic patients

Impaired attentional processing of negative facial expressions is prominent in schizophrenia and has been shown to be associated with patients’ social dysfunctions. However, little is known about when and which specific attention deficits influence social functions. Given the dynamic feature of attention, it is necessary to investigate the attention deficits in negative emotional processing unfolding in time. The current study used event-related potentials (ERPs) to investigate the temporal dynamics of attention deficits in emotion perception and their potential relationship with emotional/social impairments in neuroleptic naive schizophrenic patients. Two specific attention deficits were identified and were found to be associated with emotional/social impairments. More specifically, the deficit in orienting attention (evidenced with the reduced P1 amplitude) was correlated with expressive deficits, while the deficit in executive control of attention (evidenced with the reduced P3 amplitude) was correlated with avolition/asociality. Together, these findings may provide novel insights into the core pathophysiological processes and offer objective biomarkers for specific emotional/social impairments in schizophrenia. It is also hoped that this study helps to bridge the gap between basic cognitive deficits and relative high-level social dysfunctions in schizophrenic patients.

Altered Cerebral Blood Flow Covariance Network in Schizophrenia

Many studies have shown abnormal cerebral blood flow (CBF) in schizophrenia; however, it remains unclear how topological properties of CBF network are altered in this disorder. Here, arterial spin labeling (ASL) MRI was employed to measure resting-state CBF in 96 schizophrenia patients and 91 healthy controls. CBF covariance network of each group was constructed by calculating across-subject CBF covariance between 90 brain regions. Graph theory was used to compare intergroup differences in global and nodal topological measures of the network. Both schizophrenia patients and healthy controls had small-world topology in CBF covariance networks, implying an optimal balance between functional segregation and integration. Compared with healthy controls, schizophrenia patients showed reduced small-worldness, normalized clustering coefficient and local efficiency of the network, suggesting a shift toward randomized network topology in schizophrenia. Furthermore, schizophrenia patients exhibited altered nodal centrality in the perceptual-, affective-, language-, and spatial-related regions, indicating functional disturbance of these systems in schizophrenia. This study demonstrated for the first time that schizophrenia patients have disrupted topological properties in CBF covariance network, which provides a new perspective (efficiency of blood flow distribution between brain regions) for understanding neural mechanisms of schizophrenia.

Atypical visual and somatosensory adaptation in schizophrenia-spectrum disorders

Neurophysiological investigations in patients with schizophrenia consistently show early sensory processing deficits in the visual system. Importantly, comparable sensory deficits have also been established in healthy first-degree biological relatives of patients with schizophrenia and in first-episode drug-naive patients. The clear implication is that these measures are endophenotypic, related to the underlying genetic liability for schizophrenia. However, there is significant overlap between patient response distributions and those of healthy individuals without affected first-degree relatives. Here we sought to develop more sensitive measures of sensory dysfunction in this population, with an eye to establishing endophenotypic markers with better predictive capabilities. We used a sensory adaptation paradigm in which electrophysiological responses to basic visual and somatosensory stimuli presented at different rates (ranging from 250 to 2550 ms interstimulus intervals, in blocked presentations) were compared. Our main hypothesis was that adaptation would be substantially diminished in schizophrenia, and that this would be especially prevalent in the visual system. High-density event-related potential recordings showed amplitude reductions in sensory adaptation in patients with schizophrenia (N=15 Experiment 1, N=12 Experiment 2) compared with age-matched healthy controls (N=15 Experiment 1, N=12 Experiment 2), and this was seen for both sensory modalities. At the individual participant level, reduced adaptation was more robust for visual compared with somatosensory stimulation. These results point to significant impairments in short-term sensory plasticity across sensory modalities in schizophrenia. These simple-to-execute measures may prove valuable as candidate endophenotypes and will bear follow-up in future work.

Deficits in low beta desynchronization reflect impaired emotional processing in schizophrenia

Empirical data from previous investigations showed that emotion processing is reflected in beta, and especially in low beta event related desynchronization (ERD) (i.e. a decrease in low beta power). While recognition of social information and emotion processing are impaired in schizophrenia, no previous study analyzed induced and evoked beta oscillations in patients with schizophrenia during emotion processing. Twenty-eight subjects with schizophrenia and twenty-seven healthy controls subjects were enrolled in the study. The two study groups did not differ in age, gender and education. Participants viewed positive, neutral and negative scenes selected from the International Affective Picture System (IAPS) while 128-channel EEG was recorded. A significantly weaker low beta ERD was detected in patients relative to controls for the negative stimulus condition in the right parieto-occipital and temporal regions. Patients with decreased beta ERD showed more prominent negative symptoms and more severe deficits in psychosocial functioning. Only in the control group stronger beta ERD was detected for the negative stimuli relative to positive and neutral stimuli in the same regions. Our major finding is that impaired emotion processing in schizophrenia is reflected in decreased low beta ERD and in the diminished differences between low beta ERD to negative and non-negative emotional stimuli. Furthermore, it was found that patients with decreased beta ERD show more prominent negative symptoms and more severe deficits in psychosocial functioning.

Aberrant response inhibition and task switching in psychopathic individuals

Deficits in cognitive control have been considered a core dysfunction of psychopathy, responsible for disrupted self-control. We investigated cognitive control impairments, including difficulties with task switching, failure of response inhibition, and inability to adjust speed of responding. Participants included 16 subjects with psychopathic traits (Ps), and 22 healthy controls (HCs). We recorded behavioral responses during a Task Switching paradigm, a probe of flexible behavioral adaptation to changing contexts; and a Go/NoGo Task, which assesses response inhibition and indexes behavioral impulsivity. During task switching, Ps evidenced impairments shifting set when conflicting (incongruent) information was presented, but performed as well as HCs in the absence of such conflict. In addition, when they encountered these difficulties, they failed to adjust their speed of responding. Ps presented also with deficits in response inhibition, with many commission errors on the Go/NoGo Task. This study identified impairments in response inhibition and in set shifting in psychopathic individuals. When shifting set, they evidenced difficulties refocusing on a new task when it was incongruent with the previous task. These deficits interfere with regulation of ongoing behavior and disrupt self-regulation. Our findings suggest abnormal neural processing during suppression of inappropriate responses in psychopathic individuals.

Deconstructing violence as a medical syndrome: mapping psychotic, impulsive, and predatory subtypes to malfunctioning brain circuits

Violence is a major management issue for forensic mental health systems. Violence can be approached as a medical syndrome and deconstructed into psychotic, impulsive, and predatory subtypes, which are hypothetically mapped onto corresponding malfunctioning brain circuits. Rational management of violence balances treatment with security, while targeting each subtype of violence with approaches unique to the psychotic, impulsive, and predatory forms of violence.

Executive dysfunction and reward dysregulation: a high-density electrical mapping study in cocaine abusers

Executive function deficits and reward dysregulation, which mainly manifests as anhedonia, are well documented in drug abusers. We investigated specific aspects of executive function (inhibitory control and cognitive control), as well as anhedonia, in a cohort of current cocaine abusers in order to ascertain to what extent these factors are associated with more severe drug dependence. Participants filled out questionnaires relating to anhedonia and their addiction history. Participants also performed a response inhibition task while high-density event-related potentials (ERPs) were recorded. Electrophysiological responses to successful inhibitions (N2/P3 components) and to commission errors (ERN/Pe components) were compared between 23 current users of cocaine and 27 non-using controls. A regression model was performed to determine the association of our measures of reward dysregulation and executive function with addiction severity. As expected, cocaine users performed more poorly than controls on the inhibitory control task and showed significant electrophysiological differences. They were also generally more anhedonic than controls. Higher levels of anhedonia were associated with more severe substance use, whereas the level of executive dysfunction was not associated with more severe substance use. However, N2 amplitude was associated with duration of drug use. Further, inhibitory control and anhedonia were correlated, but only in controls. These data suggest that while executive dysfunction characterizes drug abuse, it is anhedonia, independent of executive dysfunction, that is most strongly associated with more severe use.

Recalibration of inhibitory control systems during walking-related dual-task interference: a mobile brain-body imaging (MOBI) study

Walking while simultaneously performing cognitively demanding tasks such as talking or texting are typical complex behaviors in our daily routines. Little is known about neural mechanisms underlying cortical resource allocation during such mobile actions, largely due to portability limitations of conventional neuroimaging technologies. We applied an EEG-based Mobile Brain-Body Imaging (MOBI) system that integrates high-density event-related potential (ERP) recordings with simultaneously acquired foot-force sensor data to monitor gait patterns and brain activity. We compared behavioral and ERP measures associated with performing a Go/NoGo response-inhibition task under conditions where participants (N=18) sat in a stationary way, walked deliberately or walked briskly. This allowed for assessment of effects of increasing dual-task load (i.e. walking speed) on neural indices of inhibitory control. Stride time and variability were also measured during inhibitory task performance and compared to stride parameters without task performance, thereby assessing reciprocal dual-task effects on gait parameters. There were no task performance differences between sitting and either walking condition, indicating that participants could perform both tasks simultaneously without suffering dual-task costs. However, participants took longer strides under dual-task load, likely indicating an adaptive mechanism to reduce inter-task competition for cortical resources. We found robust differences in amplitude, latency and topography of ERP components (N2 and P3) associated with inhibitory control between the sitting and walking conditions. Considering that participants showed no dual-task performance costs, we suggest that observed neural alterations under increasing task-load represent adaptive recalibration of the inhibitory network towards a more controlled and effortful processing mode, thereby optimizing performance under dual-task situations.

Emotion self-regulation and empathy depend upon longer stimulus exposure

Observation of others in pain induces positive elevation (pain effect) in late event-related potentials (ERP). This effect is associated with top-down attention regulating processes. It has previously been shown that stimulus exposure duration can affect top-down attentional modulation of response to threat-related stimuli. We investigated the effect of exposure duration on ERP response to others in pain. Two late ERP components, P3 and late positive potentials (LPP), from 18 healthy people were measured while they viewed pictures of hands in painful or neutral situations for either 200 or 500 ms, during two task conditions (pain judgment and counting hands). P3 and LPP pain effects during the pain judgment condition were significantly greater with 500 ms than 200 ms stimulus presentation. Ours is the first study to suggest that engagement of empathy-related self-regulatory processes reflected in late potentials requires longer exposure to the pain-related stimulus. Although this is important information about the relationship between early sensory and subsequent brain processing, and about engagement of self-regulatory processes, the neural basis of this time-dependence remains unclear. It might be important to investigate the relationship between stimulus duration and empathic response in clinical populations where issues of self-regulation, empathic response and speed of information processing exist.

Fearful face recognition in schizophrenia: an electrophysiological study

BACKGROUND

Emotional expressions are important acts of communication, and impairment in facial emotion recognition has been shown to be related to impairments in social cognition in schizophrenia. We used an event-related potential (ERP) paradigm to identify and delineate the temporal characteristics in the electrophysiological cascade related to fearful facial affect processing in patients with schizophrenia as compared to healthy controls.

METHODS

Twenty-four subjects with schizophrenia and 24 individually matched healthy controls participated in an emotion recognition task. Ekman faces displaying neutral and fearful facial expressions were used as stimuli. ERPs were recorded using a 128-channel EEG system.

RESULTS

Based on the analysis of Global Field Power (GFP) in the 150-190 ms time window both groups differentiated between fearful and neutral faces. Schizophrenia patients showed an additional differential processing of fearful vs. neutral faces in the 330-450 ms time window, and this ERP effect correlated with psychopathology.

CONCLUSIONS

Both patients and healthy controls differentiate fearful and neutral faces in early phases of emotion processing. Our results also indicate that schizophrenia patients show increased responsivity to fearful faces at a later processing stage. This could be related to the overrating of negative emotions, and the symptomatology associated with fear processing in patients with schizophrenia.

Mobile brain/body imaging (MoBI): High-density electrical mapping of inhibitory processes during walking

The present study investigated the feasibility of acquiring high-density event-related brain potential (ERP) recordings during treadmill walking in human subjects. The work builds upon recent studies testing the applicability of real-world tasks while obtaining electroencephalographic (EEG) recordings. Participants performed a response inhibition GO/NOGO task - designed to evoke a P3 component for correct response inhibitions and an error-related negativity (ERN) for incorrect commission errors - while speed of walking was experimentally manipulated. Robust P3 and ERN components were obtained under all experimental conditions - while participants were sitting, walking at moderate speed (2.4 km/hour), or walking rapidly (5 km/hour). Signal-to-noise ratios were remarkably similar across conditions, pointing to the feasibility of high-fidelity ERP recordings under relatively vigorous activity regimens. There is considerable research and clinical motivation to obtain high quality neurophysiological measures under more naturalistic environmental settings such as these. Strong links between cognitive load and gait abnormalities are seen in a number of clinical populations and these MoBI technologies provide highly promising methods for gaining insights into the underlying pathophysiology.