Abnormal visual event-related potentials in obsessive-compulsive disorder without panic disorder or depression comorbidity

A Review on P300 in Obsessive-Compulsive Disorder

Neuropsychological studies indicate the presence of cognitive changes in patients with obsessive-compulsive disorder (OCD). Indeed, OCD may be included among the dysfunctions of the frontal lobes and their connections with the limbic system, associative cortex, and basal ganglia. P300 is a positive component of the human event-related potential (ERP); it is associated with processes of encoding, identification, and categorization constituting, as a whole, the superior cortical function of information processing. Thus, P300 explores several areas that are implicated in OCD pathophysiology. Our aim is to review all relevant studies on the P300 component of the human ERP in order to recognize any significant central nervous system (CNS) correlate of cognitive dysfunction in OCD. A PubMed-based literature search resulted in 35 articles assessing P300 in OCD and reporting neurophysiological correlates of response inhibition, cortical hyperarousal, and over-focused attention. A decreased P300 amplitude was reported in both adult and pediatric patients, with a trend toward normalization after pharmacological treatment. Source localization studies disclosed an association between P300 abnormalities and the functioning of brain regions involved in the pathophysiology of OCD. Moreover, studies converge on the evidence of neurophysiological dysfunction in the frontal areas with impairment of the normal inhibitory processes in OCD. At least some of these electrophysiological correlates might reflect the obsessive thoughts and compulsions that characterize this disorder. These findings may also support cognitive-behavioral therapy (CBT) approaches on over-focused attention and inflexibility of compulsive behaviors, which should be associated to pharmacological treatment in these patients.

Nucleus Accumbens Stimulation Modulates Inhibitory Control by Right Prefrontal Cortex Activation in Obsessive-Compulsive Disorder

Inhibitory control is considered a compromised cognitive function in obsessive-compulsive (OCD) patients and likely linked to corticostriatal circuitry disturbances. Here, 9 refractory OCD patients treated with deep brain stimulation (DBS) were evaluated to address the dynamic modulations of large-scale cortical network activity involved in inhibitory control after nucleus accumbens (NAc) stimulation and their relationship with cortical thickness. A comparison of DBS "On/Off" states showed that patients committed fewer errors and exhibited increased intraindividual reaction time variability, resulting in improved goal maintenance abilities and proactive inhibitory control. Visual P3 event-related potentials showed increased amplitudes during Go/NoGo performance. Go and NoGo responses increased cortical activation mainly over the right inferior frontal gyrus and medial frontal gyrus, respectively. Moreover, increased cortical activation in these areas was equally associated with a higher cortical thickness within the prefrontal cortex. These results highlight the critical role of NAc DBS for preferentially modulating the neuronal activity underlying sustained speed responses and inhibitory control in OCD patients and show that it is triggered by reorganizing brain functions to the right prefrontal regions, which may depend on the underlying cortical thinning. Our findings provide updated structural and functional evidence that supports critical dopaminergic-mediated frontal-striatal network interactions in OCD.

Evidências Neurobiológicas de Viés Atencional no Transtorno Obsessivo-Compulsivo: Revisão Sistemática

Resumo O viés atencional corresponde à alocação de recursos de atenção a materiais irrelevantes à tarefa. Supõe-se que pacientes com transtorno obsessivo-compulsivo (TOC) apresentem viés atencional voltado à ameaça. Com o objetivo de descrever os achados neurobiológicos do viés atencional voltado à ameaça no TOC, foi realizada uma busca sistemática por estudos experimentais com investigação neurobiológica nas bases de dados: MEDLINE, Web of Science, Scopus e LILACS. Quatro estudos com grupo controle são descritos nos resultados, todos indicam diferenças estatisticamente significativas na atividade encefálica associada a atenção em pacientes. Os achados neurobiológicos dos estudos incluídos na revisão sugerem a alocação de recursos da atenção a estímulos irrelevantes, independente da valência emocional no TOC.

An Investigation Into Response Inhibition in Distinct Clinical Groups Within Obsessive-Compulsive Disorder

OBJECTIVE

Response inhibition has been frequently studied in obsessive-compulsive disorder (OCD) with mixed results. The inconsistent findings may stem in part from failure to consider the heterogeneity of the disorder.

METHODS

The authors examined behavioral and event-related potential (ERP) components (N2 and P3) during a simple response inhibition go/nogo task in a sample of patients with OCD (N=48) and control subjects (N=53). Comparisons in behavioral and electrophysiological measures were made between groups (OCD compared with control) and within the OCD group in terms of symptom clusters (symmetry, forbidden thoughts, and cleaning) and comorbidity status (OCD only and OCD with depression).

RESULTS

In the OCD group, the N2 component appeared more frontally localized compared with the control group. Participants with OCD demonstrated longer N2 latency and a larger difference in N2 between the nogo and go conditions, suggesting slower but greater conflict monitoring. P3 had a larger amplitude in the OCD group compared with the control group, indicative of greater response inhibition, but was also reduced in the nogo compared with go condition, suggesting suppressed response inhibition. No significant differences were found between symptom clusters, but patients with OCD only made more omission errors compared with patients with OCD and comorbid depression. The latter cohort also had faster P3 latencies, which, combined with the behavioral data, indicates slightly improved response inhibition when comorbid depression is found.

CONCLUSIONS

On the basis of these results, it would seem unlikely that symptom clusters have contributed to previous inconsistencies in the literature. Comorbid depression, which may have affected previous results, should be considered in future research.

Early cognitive processes in OCD: An ERP study

BACKGROUND

Obsessive-compulsive disorder (OCD) is characterized by persistent, intrusive, and distressing obsessions and/or compulsions and is associated with marked impairments in quality of life. The goal of the present study was to examine initial stages of information processing, specifically, perceptual and attention orientation phases that precede response preparation in OCD.

METHODS

The P3 event-related potential (ERP) component was used as a measure of early cognitive processes of visual stimulus perception. ERPs were recorded while 38 participants diagnosed with OCD and 38 healthy controls performed a passive visual oddball task with neutral and angry schematic faces.

RESULTS

OCD participants demonstrated significantly enhanced P3 amplitude over bilateral parietal areas in response to neutral stimuli that activate basic primary perceptual processes. Emotional valence reduced this effect such that OCD patients did not differ from healthy controls in P3 amplitude under the angry stimuli condition.

LIMITATIONS

Patients in this study were noncomorbid and unmedicated partially limiting the generalizability of the results.

CONCLUSIONS

Our hypothesis of altered early perceptual processes in OCD was supported. These alterations, specific to OCD and not anxiety and depression symptoms, may represent distracted primary cognitive processes in OCD, possibly serving as a basic source for compulsion initiation.

Neuropsychological, electrophysiological and neurological impairments in patients with obsessive compulsive disorder, their healthy siblings and healthy controls: Identifying potential endophenotype(s)

The etiology of obsessive-compulsive disorder (OCD) has not been clarified. This study aimed to investigate the cognitive, neurological, electrophysiological functions which are reflected in executive functions, memory, visuospatial integration; neurological examination and auditory event related potentials (AERP) (N100, N200, P200 and P300) in patients with OCD, their siblings, and control subjects and to determine potential endophenotypic markers. Thirty-three patients with OCD, 18 siblings and 21 controls; matched for age, gender and years of education were included. Yale Brown Obsessive Compulsive Symptoms Checklist Scale, Hamilton Depression-Rating Scale, an exhaustive neuropscyhological test battery and Neurological Evaluation Scale were administered. Their AERP recordings were obtained. Executive functions and visuospatial integration were highly impaired in patients and slightly in their siblings compared to controls. P200 amplitude was sorted as siblings>patients>controls. P300 amplitude was sorted as patients<siblings<controls. Neurological Evaluation Scale scores were lower in patients compared to siblings and controls. The logistic regression analysis showed that, higher P300 amplitude, better performance on block design test and faster completion of Stroop test would predict being in the control group, whereas higher P200 amplitude would predict being in the case (patient and sibling) groups. We suggest that these seem to be the potential endophenotypes of OCD.

Electrophysiology of facilitation priming in obsessive-compulsive and panic disorders

OBJECTIVE

Repeated experience with stimuli often primes faster, more efficient neuronal and behavioural responses. Exaggerated repetition priming effects have previously been reported in obsessive-compulsive disorder (OCD), however little is known of their underlying neurobiology or disorder-specificity, hence we investigated these factors.

METHODS

We examined event-related potentials (ERPs) and behaviour while participants with OCD, panic disorder and healthy controls (20 per group) performed a Go/NoGo task which manipulated target repetition sequences.

RESULTS

Both clinical groups showed stronger reaction time (RT) priming than HCs, which in OCD was greater in a checking, than washing, subgroup. Both clinical groups had similar RT deficits and ERP anomalies across several components, which correlated with psychopathology and RT priming. In OCD alone, N1 latency tended to increase to repeated stimuli, correlated with O-C symptoms, whereas it decreased in other groups. OCD-checkers had smaller target P2 amplitude than all other groups.

CONCLUSIONS

Enhanced neural priming is not unique to OCD and may contribute to salient sensory-cognitive experiences in anxiety generally. These effects are related to symptom severity and occur to neutral stimuli and in the context of overall RT impairment, suggesting they may be clinically relevant and pervasive. The results indicate overlapping information-processing and neurobiological factors across disorders, with indications of OCD-specific trends and subgroup differences.

SIGNIFICANCE

This first electrophysiological investigation of OCD priming in OCD to include anxious controls and OCD subgroups allows for differentiation between overlapping and OCD-specific phenomena, to advance neurobiological models of OCD.

N2 and P3 potentials in early-onset and late-onset patients with obsessive-compulsive disorder

BACKGROUND

Impaired cognitive control processes may be central in the pathogenesis of obsessive-compulsive disorder (OCD). Our objective was to evaluate cognitive control processes with event-related potentials in early-onset OCD (EO) and late-onset OCD (LO), which are suggested to have distinct characteristics.

METHODS

Participants were unmedicated EO (n = 26) and LO patients (n = 33) without comorbid psychopathology and healthy controls (n = 54). Go/No-go tasks with 50 and 80% Go trial probabilities were implemented to manipulate the strength of response conflict and inhibitory demands.

RESULTS

LO patients had shorter N2 latencies than controls and did not show the N2 amplitude increase seen in controls with the increase in Go trial probability as suggestive of abnormal conflict monitoring processes. Both EO and LO patients showed smaller P3 increase than controls with the increase in Go trial probability, suggesting problems in modifying attentional control with changes in task demands. P3 was more anteriorly distributed in LO patients than controls. Additionally, P3 increase, with the increase in Go trial probability, was larger in frontal and central sites than in parietal sites in controls, whereas in EO patients it was almost homogenous across anteroposterior sites.

CONCLUSIONS

N2 processes were affected only in LO, whereas P3 processes were affected in both EO and LO, although, somewhat differently. P3 distributions suggest that EO and LO patients have differences concerning the contributions of frontal and parietal components of attentional networks to the execution of Go/No-go tasks. Our results imply that EO and LO are distinct subtypes affecting the cognitive control systems differently.

The neurobiological link between OCD and ADHD

Obsessive compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD) are two of the most common neuropsychiatric diseases in paediatric populations. The high comorbidity of ADHD and OCD with each other, especially of ADHD in paediatric OCD, is well described. OCD and ADHD often follow a chronic course with persistent rates of at least 40–50 %. Family studies showed high heritability in ADHD and OCD, and some genetic findings showed similar variants for both disorders of the same pathogenetic mechanisms, whereas other genetic findings may differentiate between ADHD and OCD. Neuropsychological and neuroimaging studies suggest that partly similar executive functions are affected in both disorders. The deficits in the corresponding brain networks may be responsible for the perseverative, compulsive symptoms in OCD but also for the disinhibited and impulsive symptoms characterizing ADHD. This article reviews the current literature of neuroimaging, neurochemical circuitry, neuropsychological and genetic findings considering similarities as well as differences between OCD and ADHD.

How specific are inhibitory deficits to obsessive-compulsive disorder? A neurophysiological comparison with panic disorder

OBJECTIVE

Impaired inhibition may perpetuate repetitive symptoms in obsessive-compulsive disorder (OCD), however OCD-specific deficits have yet to be established. We investigated neural correlates of inhibition in OCD vs. healthy and anxious controls.

METHODS

ERPs and reaction times (RTs) were compared between participants with OCD (n=20), panic disorder (PD; n=20) and healthy controls (HCs; n=20) during an adapted Go/NoGo task, which manipulated inhibitory difficulty.

RESULTS

A classic P3 NoGo anteriorisation effect occurred across groups. Both clinical groups showed RT impairment, and similar topographical anomalies of several (P2, N2 and P3) ERP components. Notably, both clinical groups lacked the strong frontally maximal N2 component topography seen in the HCs, across stimuli. Additionally, with increasing inhibitory difficulty, N2 latency increased in HCs but not in the clinical groups.

CONCLUSIONS

Unexpectedly, ERP and behavioural anomalies during inhibition in OCD were not qualitatively different to those in PD, but were generally more severe. Common general and inhibitory deficits may underlie intrusive mental phenomena in both conditions.

SIGNIFICANCE

This first ERP response inhibition study in OCD to include anxious controls disconfirmed hypotheses regarding OCD-specific inhibitory deficits, indicating the importance of comparing OCD to other conditions, to evaluate neurobiological models.

Modafinil increases reward salience in a slot machine game in low and high impulsivity pathological gamblers

This study examined the effects of modafinil (200 mg) on slot machine betting profiles from a previous sample of low and high impulsivity (LI/HI) pathological gamblers (10/Group; Zack and Poulos, 2009). Hierarchical regression assessed the prospective relationship between Payoff and Bet Size on consecutive trials, along with moderating effects of Group, Cumulative Winnings (low/high) and Phase of game (early/late) under drug and placebo. Y intercepts for the simple regressions of Bet Size on Payoff indexed overall motivation to bet. Under placebo, both groups gauged their bets less closely to the preceding Payoff as trials continued when Winnings were low but not high. Under modafinil, both groups gauged their bets more closely to the preceding Payoff when Winnings were low but gauged their bets less closely to the previous Payoff when Winnings were high. The tendency to gauge bets closely to the previous Payoff coincided with a bias toward low overall Bet Size, and modafinil accentuated this relationship, in LI but not HI subjects. Results suggest that modafinil increases the salience of environmental rewards, leading to more tightly calibrated responses to individual rewards when resources are low, but progressively loosens reward-response calibration when resources are high. Increased relative impact of phasic vs. tonic dopamine signals may account for patterns seen at low vs. high Winnings, respectively, under the drug. Clinically, modafinil may deter pathological gamblers from chasing losses but also encourage them to continue betting rather than quit while they are ahead. Whether low-dose modafinil confers more uniform benefits deserves investigation.

Neuroimaging of cognitive brain function in paediatric obsessive compulsive disorder: a review of literature and preliminary meta-analysis

Obsessive compulsive disorder (OCD) is a frequent psychiatric disorder with a prevalence of 1-3 %, and it places an enormous burden on patients and their relatives. Up to 50 % of all cases suffer from onset in childhood or adolescence, and the disorder often takes a chronic course with a poor long-term prognosis. Paediatric OCD, with its high familiality, is often referred to as a distinct OCD subtype that coincides with a developmental period in which the prefrontal cortex exhibits extensive structural and functional maturation. In the present review, we included all studies examining cognitive brain activation in children and/or adolescents with OCD. We conducted extensive literature searches for relevant articles (Pubmed, ScienceDirect) and summarize, tabulate, and discuss their results. For the eight activation studies using functional magnetic resonance imaging, we also performed preliminary meta-analyses to assess the most consistent hypo- and hyperactivation in paediatric OCD patients during cognitive task performance. The review of literature as well as our preliminary meta-analyses of paediatric studies indicated altered functional activation in the same brain regions of affective and cognitive cortico-striatal-thalamic (CST) circuits as for adult OCD patients despite some variations in the direction of activation difference. The still small number of studies that examined brain activation in paediatric OCD patients thereby largely converged with previous findings in adult patients and with the established neurobiological models of CST circuit dysfunction in OCD.

Cognitive event-related potentials differentiate schizophrenia with obsessive-compulsive disorder (schizo-OCD) from OCD and schizophrenia without OC symptoms

Clinical and neurobiological evidence suggests that concurrent presentation of schizophrenia and obsessive-compulsive (schizo-OCD) symptoms represents a distinct clinical entity. Given that obsessive-compulsive disorder (OCD) and schizophrenia have been modeled as having different neurofunctional profiles, the overlap between them represents a heuristic challenge for cognitive and endophenotype research. Event-related potentials (ERPs) may be used to probe neurophysiological correlates of the cognitive, emotional and behavioral disturbances found in neuropsychiatric entities such as schizo-OCD. Here we measure ERPs during a discriminative response task (DRT) in patients presenting with the DSM-IV criteria for both schizophrenia and OCD. We also performed these measurements in patients with OCD without psychotic features, as well as in patients with schizophrenia without OC symptoms. Schizo-OCD patients showed a distinct ERP pattern, with abnormally increased target activation (akin to OCD patients, but unlike the pattern observed in schizophrenic patients) and reduced P300 amplitudes (akin to schizophrenic patients, but unlike OCD patients). Similar to the control subjects, schizo-OCD patients showed larger amplitudes in the non-target condition than in the target condition. These results suggest that schizo-OCD may not only be a distinct clinical entity from pure OCD and schizophrenia, but it may also be characterized by a distinguishable neurophysiologic pattern. Neurobiological underpinnings deserve further considerations and might drive to a definition of a distinctive endophenotype for schizo-OCD in the de-construction of the schizophrenia endophenotype.

Influence of comorbid obsessive-compulsive symptoms on brain event-related potentials in Gilles de la Tourette syndrome

Approximately 30 to 50% of people suffering from Gilles de la Tourette Syndrome (GTS) also fulfill diagnostic criteria for obsessive-compulsive disorder (OCD). Despite this high degree of comorbidity, very few studies have addressed the question of obsessive-compulsive symptoms (OCS) in GTS patients using specific brain event-related potentials (ERP) responses. The aim of the current study was to quantify neurocognitive aspects of comorbidity, using ERPs. Fourteen adults with GTS (without OCD) were compared to a group of 12 participants with GTS and comorbid obsessive-compulsive symptoms (GTS+OCS), to a group of 15 participants with OCD and to a group of 14 control participants without neurological or psychiatric problems. The P200 and P300 components were recorded during a visual counting oddball task. Results showed intact P200 amplitude in all groups, whilst the P300 amplitude was affected differentially across groups. The P300 oddball effect was reduced in participants in both OCD and GTS+OCS groups in the anterior region. However, the P300 oddball effect was significantly larger in participants of the GTS group compared to all other groups, mostly in the parietal region. These findings suggest that adults with GTS are characterized by enhanced working memory updating processes and that the superimposition of OCS can lead to a reduction of these processes. The discrepancy between our findings and results obtained in previous studies on GTS could reflect the modulating effect of OCS on late ERP components.

Electrophysiological correlates of behavioral response inhibition in patients with obsessive-compulsive disorder

In this study, we have attempted to determine the electrophysiological correlates of behavioral response inhibition in patients with obsessive-compulsive disorder (OCD). To evaluate response inhibition ability, we have used the Go/NoGo task and measured N2 and P3 event-related potential (ERP) components. Both the OCD and control groups exhibited greater and more frontally distributed N2 and P3 amplitudes in the NoGo condition compared to what we observed in the Go condition. However, the patients with OCD also manifested reduced NoGo-N2 and Go-N2 amplitudes at the frontocentral electrode sites compared to the controls. In addition, the NoGo-N2 amplitudes were more posteriorly distributed in patients with OCD than in controls. The NoGo-N2 amplitudes and latencies measured at the central sites were also negatively correlated with the obsession score on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). The OCD and control groups were comparable with regard to Go-P3 and NoGo-P3 amplitude and latencies. Our findings suggest dysfunctions in frontal regions mediating response inhibition in OCD, consistent with the involvement of response inhibition in the pathophysiology of this disorder. In addition, NoGo-N2 seems to result in more accurate response inhibition measurements in patients with OCD than does NoGo-P3.

Neural correlates of fast stimulus discrimination and response selection in top-level fencers

Flexible adaptation of behaviour is highly required in some sports, such as fencing. In particular, stimulus discrimination and motor response selection and inhibition processes are crucial. We investigated the neural mechanisms responsible for fencers' fast and flexible behaviour recording event-related potentials (ERPs) in discriminative reaction task (DRT, Go/No-go task) and simple reaction task (SRT) to visual stimuli. In the DRT, in addition to faster RTs measured in fencers with respect to control subjects, three main electrophysiological differences were found. First, attentional modulation of the visual processing taking place in the occipital lobes and reaching a peak at 170 ms was enhanced in the athletes group. Second, the activity in the posterior cingulate gyrus, associated with the stimulus discrimination stage, started earlier in fencers than controls (150 ms versus 200 ms) and the peak had larger amplitude. Third, the activity at the level of the prefrontal cortex (time range: 250-350 ms), associated with response selection stage and particularly with motor inhibition process, was stronger in fencers. No differences between athletes and controls were found in the SRT for both ERPs and RTs. Concluding, the fencers' ability to cope to the opponent feint switching quickly from an intended action to a new more appropriate action is likely due to a faster stimulus discrimination facilitated by higher attention and by stronger inhibition activity in prefrontal cortex.

Understanding Obsessive–Compulsive Disorder: Focus on Decision Making

Current approaches to obsessive-compulsive disorder (OCD) have suggested that neurobiological abnormalities play a crucial role in the etiology and course of this psychiatric illness. In particular, a fronto-subcortical circuit, including the orbitofrontal cortex, basal ganglia and thalamus appears to be involved in the expression of OCD symptoms. Neuropsychological studies have also shown that patients with OCD show deficits in cognitive abilities that are strictly linked to the functioning of the frontal lobe and its related fronto-subcortical structures, such as executive functioning deficits and insufficient cognitive-behavioral flexibility. This article focuses on decision making, an executive ability that plays a crucial role in many real-life situations, whereby individuals choose between pursuing strategies of action that involve only immediate reward and others based on long-term reward. Although the role of decision-making deficits in the evolution of OCD requires further research, the collected findings have significant implications for understanding the clinical and behavioral heterogeneity that characterizes individuals with OCD.

Differences in behavioural phenotype between parental deletion and maternal uniparental disomy in Prader-Willi syndrome: an ERP study

OBJECTIVE

Paternal deletion and maternal uniparental disomy are the principal genetic subtypes associated with Prader-Willi syndrome (PWS). Recent clinical findings suggest differences in phenotype between these subtypes. The present experimental study addresses this issue using a cognitive psycho-physiological setup.

METHODS

Behaviour and event-related brain activity (ERP) was recorded by a continuous performance response inhibition task (CPT-AX) in adults with paternal deletion PWS (n=11), maternal uniparental disomy PWS (n=11) and normal controls (n=11). The dependent behavioural variables of the CPT-AX task were reaction time and correct scores. For the ERPs the N200 and P300 components were included which are related to early modality-specific inhibition and late general inhibition, respectively.

RESULTS

The disomy group had fewer correct scores and increased reaction times as compared to the CPT-AX task than the control and deletion group. Both PWS subgroups differed significantly from the control group for the N200 amplitude. Only the control group showed the typical task modulation for the N200 amplitude. The amplitude of the P300 component was considerably smaller in the uniparental disomy group than in the deletion and control groups.

CONCLUSIONS

The ERP results suggest that early modality specific inhibition is impaired in both PWS genetic subtypes. Late general inhibition is impaired in the uniparental disomy group only. Thus, although the ERP data suggests a common impairment in early visual inhibition processing, uniparental disomy and parental deletion genetic PWS subtypes clearly differ in their behavioural and brain activation phenotypes.

SIGNIFICANCE

The present study is the first experimental demonstration which explains the two principal genetic mechanisms that hinder the expression of the genes at 15q11-q13g in PWS result in different behavioural phenotype.

Reduced response-inhibition in obsessive-compulsive disorder measured with topographic evoked potential mapping

Recent neuroimaging studies have suggested that a hyperactivity of the frontal-striate neuronal circuits, including the orbitofrontal cortex and the basal ganglia, mediates the symptomatology of obsessive-compulsive disorder (OCD). However, there is also some evidence that the superior frontal cortex is less activated in OCD, and this local hypoactivity has been shown to be negatively associated with the symptomatology. As the superior frontal cortex is believed to be involved in inhibitory control, this study investigated the brain electrical activity during response inhibition in OCD. Twelve patients with OCD and 12 healthy controls performed a cued Go-NoGo task (continuous performance test), while event-related potentials were registered with 21 electrodes. Patients reacted significantly faster than controls, but did not differ from controls regarding the error rate. As a main result, we found a reduced frontal activity during the NoGo condition in OCD, which was condensed in a reduced anteriorisation of the brain electrical field. We suggest that this inhibitory deficit in OCD has a major contribution to the pathophysiology of OCD, which is underscored by the fact that the anteriorisation during the NoGo condition (NGA) was negatively correlated with the symptomatology as measured by the Yale-Brown Obsessive-Compulsive Scale.

Error-related brain activity in obsessive-compulsive undergraduates

Error-related negativity (ERN/Ne) is a component of the event-related brain potential (ERP) associated with monitoring action and detecting errors. It is a sharp negative deflection that generally occurs from 50 to 150 ms following response execution and has been associated with activity involving the anterior cingulate cortex (ACC). An enhanced ERN has recently been observed in patients with obsessive-compulsive disorder (OCD). We extended these findings by measuring the ERN in college undergraduates with OC characteristics as measured by the Obsessive-Compulsive Inventory (OCI). Eighteen high-OC subjects and 17 low-OC subjects performed a modified Stroop task with equal emphasis placed on speed and accuracy. Response-locked ERPs revealed a frontally maximal negativity associated with erroneous responses that was significantly larger in the high-OCI group. There were no performance differences between the two groups. Our results support the view that the characteristics associated with OCD are related to hyper-functioning error and action-monitoring processes.

Discrepant target detection and action monitoring in obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) has been related to altered mechanisms of action monitoring and target detection, and it has been hypothesized that hyperactive striatal-cortical circuits constitute the underlying pathophysiology. This study used event-related brain potentials (ERPs) to explore this hypothesis. A choice reaction time experiment was carried out in a group of OCD patients and a normal comparison group. The P3b component of the ERP to targets was taken as an indicator of the target-evaluation process and the response-locked error-related negativity (ERN) served as an indicator of action monitoring. We hypothesized that the OCD group would show a shortened P3b latency and an amplitude-enhanced ERN. Consistent with our expectations, the P3b latency was shorter and the ERN amplitude was higher in the OCD group. Unexpectedly, we also observed a prolonged ERN latency in the OCD group and a more posterior topography of this component. The data provide partial support for the hypothesis of a hyperactive neural network in OCD. In addition the disorder must involve pathophysiological processes that are presumably related to other aspects of its complex and heterogeneous clinical hallmarks.