Abnormalities of internally generated saccades in obsessive-compulsive disorder

Increased error rate and delayed response to negative emotional stimuli in antisaccade task in obsessive-compulsive disorder

Ample evidence links impaired inhibitory control, attentional distortions, emotional dysregulation, and obsessive-compulsive disorder (OCD). However, it remains unclear what underlies the deficit that triggers the OCD cycle. The present study used an antisaccade paradigm with emotional valences to compare eye movement patterns reflecting inhibitory control and attention switching in OCD and healthy control groups. Thirty-two patients with OCD and thirty healthy controls performed the antisaccade task with neutral, positive, and negative visual images served as fixation stimuli. Presentation of the fixation stimulus overlapped with target stimuli appearance for 200 ms. The OCD group showed more errors to negative stimuli than the control group and they also performed antisaccades more slowly to negative and neutral stimuli than positive ones. Other patterns, including mean gaze velocity of correct antisaccades did not differ between groups. The mean gaze velocity of correct antisaccades was higher for negative and positive stimuli than for neutral stimuli in both groups. The peak velocity parameter did not show any differences either between groups or between valences. The findings support a hypothesis that an attentional bias toward negative stimuli interferes with inhibitory control in OCD.

Antisaccade task performance in obsessive-compulsive disorder and its clinical correlates

OBJECTIVE

Obsessive-Compulsive Disorder (OCD) is characterized by abnormalities in the cortico-striato-thalamo-cortical (CSTC) circuitry of the brain. Antisaccade eye movement tasks measure aspects of the voluntary control of behaviour that are sensitive to CSTC circuitry dysfunction.

METHOD

In this study, we examined antisaccade eye movement parameters of OCD patients in comparison with healthy controls (HC). In addition, we also examined the relationship between the antisaccade eye movement parameters and the severity of OCD. Antisaccade performance among right handed OCD patients (N = 65) was compared to matched right handed HC (N = 57). Eye tracking data during the task performance were collected using an Eye-Link eye-tracker at 1000-Hz sampling rate. OCD symptom severity was evaluated using Yale-Brown obsessive compulsive scale.

RESULTS

The antisaccade error percentage was significantly greater in OCD patients than HC (p < 0.001). In addition, OCD patients had less accurate final eye position compared to HC (p < 0.001). There were no significant correlation between antisaccade parameters and OCD severity measures.

CONCLUSION

Deficient performance in antisaccade task supports CSTC abnormality in OCD and this appears to be independent of the illness severity. Examining this in remitted participants with OCD and in unaffected first degree relatives could help ascertaining their endophenotype validity.

Neuropsychiatric aspects of Parkinson disease psychopharmacology: Insights from circuit dynamics

Parkinson disease (PD) is a neurodegenerative disorder with a complex pathophysiology characterized by the progressive loss of dopaminergic neurons within the substantia nigra. Persons with PD experience several motoric and neuropsychiatric symptoms. Neuropsychiatric features of PD include depression, anxiety, psychosis, impulse control disorders, and apathy. In this chapter, we will utilize the National Institutes of Mental Health Research Domain Criteria (RDoC) to frame and integrate observations from two prevailing disease constructions: neurotransmitter anomalies and circuit physiology. When there is available evidence, we posit how unified translational observations may have clinical relevance and postulate importance outside of PD. Finally, we review the limited evidence available for pharmacologic management of these symptoms.

Eye movement tracking in pediatric obsessive compulsive disorder

Till date researchers have elucidated the neurobiological substrates in OCD using methods like neuroimaging. However, a potential biomarker is still elusive. The present study is an attempt to identify a potential biomarker in pediatric OCD using eye tracking. The present study measured pro-saccade and anti-saccade parameters in 36 cases of pediatric OCD and 31 healthy controls. There was no significant difference between cases and controls in the error rate, peak velocity, position gain and latency measures in both pro-saccade and anti-saccade eye tracking tasks. With age, anti-saccades become slower in velocity, faster in response and more accurate irrespective of disorder status of the child. Pro-saccades also show a similar effect that is less prominent than anti-saccades. Gain measures more significantly vary with age in children with OCD than the controls, whereas latency measures positively correlated with age in children with OCD as opposed to being negatively correlated in the controls. Findings of this study do not support any of the eye tracking measures as putative diagnostic bio-markers in OCD. However, latency and gain parameters across different age groups in anti-saccade tasks need to be explored in future studies.

Self-reported volitional control in adolescents and young adults from a community cohort: Associations with current, past and future mental disorders

Alterations in volitional control have been found for various mental disorders. However, it remains unclear to which degree such alterations vary by type of psychopathology and constitute preceding vulnerabilities or correlates of mental disorders. DSM-IV mental disorders were assessed among adolescents and young adults from the community at baseline (age 14-24) and in up to 3 follow-up assessments over 10 years (n = 2515) using a standardized diagnostic interview (DIA-X/M-CIDI). Self-reported volitional control was assessed at second follow-up (T2) when subjects were aged 17-28 using the German version of the Short Form of the Volitional Components Inventory. Linear regressions adjusted for sex, age and lifetime disorders revealed that anxiety and affective disorders were associated with widespread alterations in self-reported volitional control (lower self regulation, higher self inhibition and volitional inhibition), while substance use disorders were specifically associated with higher volitional inhibition. Logistic regressions adjusted for sex, age and prior lifetime psychopathology revealed that lower self-reported volitional control at T2 predicted incident panic, social phobia and substance use at T3 (follow-up interval M = 4.8 years). Findings point toward at least partly disorder-specific alterations in volitional control in mental disorders, which might be antecedent vulnerability factors and thus useful to guide early recognition and prevention.

Impaired Antisaccades in Obsessive-Compulsive Disorder: Evidence From Meta-Analysis and a Large Empirical Study

Increasing evidence indicates that patients with obsessive-compulsive disorder (OCD) exhibit alterations in fronto-striatal circuitry. Performance deficits in the antisaccade task would support this model, but results from previous small-scale studies have been inconclusive as either increased error rates, prolonged antisaccade latencies, both or neither have been reported in OCD patients. In order to address this issue, we investigated antisaccade performance in a large sample of OCD patients (n = 169) and matched control subjects (n = 183). As impaired antisaccade performance constitutes a potential endophenotype of OCD, unaffected first-degree relatives of OCD patients (n = 100) were assessed, as well. Furthermore, we conducted a quantitative meta-analysis to integrate our data with previous findings. In the empirical study, OCD patients exhibited significantly increased antisaccade latencies, intra-subject variability (ISV) of antisaccade latencies, and antisaccade error rates. The latter effect was driven by errors with express latency (80-130 ms), as patients did not differ significantly from controls with regards to regular errors (>130 ms). Notably, unaffected relatives of OCD patients showed elevated antisaccade express error rates and increased ISV of antisaccade latencies, as well. Antisaccade performance was not associated with state anxiety within groups. Among relatives, however, we observed a significant correlation between antisaccade error rate and harm avoidance. Medication status of OCD patients, symptom severity, depressive comorbidity, comorbid anxiety disorders and OCD symptom dimensions did not significantly affect antisaccade performance. Meta-analysis of 10 previous and the present empirical study yielded a medium-sized effect (SMD = 0.48, p < 0.001) for higher error rates in OCD patients, while the effect for latencies did not reach significance owing to strong heterogeneity (SMD = 0.51, p = 0.069). Our results support the assumption of impaired antisaccade performance in OCD, although effects sizes were only moderately large. Furthermore, we provide the first evidence that increased antisaccade express error rates and ISV of antisaccade latencies may constitute endophenotypes of OCD. Findings regarding these more detailed antisaccade parameters point to potentially underlying mechanisms, such as early pre-stimulus inhibition of the superior colliculus.

Behavioural and computational varieties of response inhibition in eye movements

Response inhibition is the ability to override a planned or an already initiated response. It is the hallmark of executive control as its deficits favour impulsive behaviours, which may be detrimental to an individual's life. This article reviews behavioural and computational guises of response inhibition. It focuses only on inhibition of oculomotor responses. It first reviews behavioural paradigms of response inhibition in eye movement research, namely the countermanding and antisaccade paradigms, both proven to be useful tools for the study of response inhibition in cognitive neuroscience and psychopathology. Then, it briefly reviews the neural mechanisms of response inhibition in these two behavioural paradigms. Computational models that embody a hypothesis and/or a theory of mechanisms underlying performance in both behavioural paradigms as well as provide a critical analysis of strengths and weaknesses of these models are discussed. All models assume the race of decision processes. The decision process in each paradigm that wins the race depends on different mechanisms. It has been shown that response latency is a stochastic process and has been proven to be an important measure of the cognitive control processes involved in response stopping in healthy and patient groups. Then, the inhibitory deficits in different brain diseases are reviewed, including schizophrenia and obsessive-compulsive disorder. Finally, new directions are suggested to improve the performance of models of response inhibition by drawing inspiration from successes of models in other domains.This article is part of the themed issue 'Movement suppression: brain mechanisms for stopping and stillness'.

Volitional saccade performance in a large sample of patients with obsessive-compulsive disorder and unaffected first-degree relatives

Recent evidence indicates that patients with obsessive-compulsive disorder (OCD) as well as their unaffected first-degree relatives show deficits in the volitional control of saccades, suggesting that volitional saccade performance may constitute an endophenotype of OCD. Here, we aimed to replicate and extend these findings in a large, independent sample. One hundred and fifteen patients with OCD, 103 healthy comparison subjects without a family history of OCD, and 31 unaffected first-degree relatives of OCD patients were examined using structured clinical interviews and performed a volitional saccade task as well as a prosaccade task. In contrast to previous reports, neither patients nor relatives showed impairments in the performance of volitional saccades compared to healthy controls. Notably, medicated patients did not differ from nonmedicated patients, and there was no effect of depressive comorbidity. Additional analyses investigating correlations between saccade performance and OCD symptom dimensions yielded no significant associations. In conclusion, the present results do not support the notion that volitional saccade execution constitutes an endophenotype of OCD. Possible explanations for inconsistencies with previous studies are discussed.

Back to basics: The effects of block vs. interleaved trial administration on pro- and anti-saccade performance

The pro and anti-saccade task (PAT) is a widely used tool in the study of overt and covert attention with promising potential role in neurocognitive and psychiatric assessment. However, specific PAT protocols can vary significantly between labs, potentially resulting in large variations in findings across studies. In light of recent calls towards a standardization of PAT the current study's objective was to systematically and purposely evaluate the effects of block vs. interleaved administration—a fundamental consideration—on PAT measures in a within subject design. Additionally, this study evaluated whether measures of a Posner-type cueing paradigm parallels measures of the PAT paradigm. As hypothesized, results indicate that PAT performance is highly susceptible to administration mode. Interleaved mode resulted in larger error rates not only for anti (blocks: M = 22%; interleaved: M = 42%) but also for pro-saccades (blocks: M = 5%; interleaved: M = 12%). This difference between block and interleaved administration was significantly larger in anti-saccades compared to pro-saccades and cannot be attributed to a 'speed/accuracy tradeoff'. Interleaved mode produced larger pro and anti-saccade differences in error rates while block administration produced larger latency differences. Results question the reflexive nature of pro-saccades, suggesting they are not purely reflexive. These results were further discussed and compared to previous studies that included within subject data of blocks and interleaved trials.

Saccadic Eye Movements in Anorexia Nervosa

Background

Anorexia Nervosa (AN) has a mortality rate among the highest of any mental illness, though the factors involved in the condition remain unclear. Recently, the potential neurobiological underpinnings of the condition have become of increasing interest. Saccadic eye movement tasks have proven useful in our understanding of the neurobiology of some other psychiatric illnesses as they utilise known brain regions, but to date have not been examined in AN. The aim of this study was to investigate whether individuals with AN differ from healthy individuals in performance on a range of saccadic eye movements tasks.

Methods

24 females with AN and 25 healthy individuals matched for age, gender and premorbid intelligence participated in the study. Participants were required to undergo memory-guided and self-paced saccade tasks, and an interleaved prosaccade/antisaccade/no-go saccade task while undergoing functional magnetic resonance imaging (fMRI).

Results

AN participants were found to make prosaccades of significantly shorter latency than healthy controls. AN participants also made an increased number of inhibitory errors on the memory-guided saccade task. Groups did not significantly differ in antisaccade, no-go saccade or self-paced saccade performance, or fMRI findings.

Discussion

The results suggest a potential role of GABA in the superior colliculus in the psychopathology of AN.

Shared and distinct oculomotor function deficits in schizophrenia and obsessive compulsive disorder

Detailed analysis of oculomotor function phenotypes in antisaccade, smooth eye pursuit, and active fixation tasks was performed in a sample of 44 patients with schizophrenia, 34 patients with obsessive compulsive disorder (OCD), and 45 matched healthy controls. A common pattern of performance deficits in both schizophrenia and OCD emerged including higher antisaccade error rate, increased latency for corrective antisaccades, as well as higher rates of unwanted saccades in smooth eye pursuit compared to healthy controls. This common pattern could be related to the dysfunction of a network of cognitive control that is present in both disorders, including the dorsolateral prefrontal cortex, the posterior parietal cortex, and the anterior cingulate cortex. In contrast, only patients with schizophrenia showed a specific increase for correct antisaccade mean latency and the intrasubject variability of latency for error prosaccades as well as a decrease in the gain for smooth eye pursuit, suggesting a specific deficit in saccadic motor control and the frontal eye field in schizophrenia that is not present in OCD. A specific deficit in fixation stability (increased frequency of unwanted saccades during active fixation) was observed only for OCD patients pointing to a deficit in the frontostriatal network controlling fixation. This deficit was pronounced for OCD patients receiving additional antipsychotic medication. In conclusion, oculomotor function showed shared and distinct patterns of deviance for schizophrenia and OCD pointing toward shared and specific neurobiological substrates for these psychiatric disorders.

Obsessed not to forget: lack of retrieval-induced suppression effect in obsessive-compulsive disorder

The aim of the present study was to investigate the role of executive functions in resolving memory interference in a clinical sample of patients with obsessive-compulsive disorder (OCD). Retrieval of memories has been shown to involve some form of executive act that diminishes the accessibility of rival memory traces, leading to retrieval-induced forgetting (RIF). These executive control processes might suppress unwanted thoughts and irrelevant memories during competitive retrieval. We assessed RIF with the retrieval practice paradigm among 25 OCD patients and 25 healthy controls matched for age and education. Retrieval of target memories led to enhancement of target memory recall in both groups, but suppression of related memories (RIF) occurred only among controls. Our results suggest that suppression of irrelevant, interfering memories during competitive recall is impaired in OCD.

Variability in the decision process leading to saccades: a specific marker for schizophrenia?

In a previous study, deviance in the reaction time (RT) distribution of saccades for patients with schizophrenia was explained using an oculomotor decision model. Here, RTs of visually guided saccades in young healthy men, healthy children, older adults, patients with schizophrenia, and patients with obsessive compulsive disorder (OCD) were modeled to study the specificity of this decision process deviance for schizophrenia. The mean decision rate to saccade decreased with age in children and increased in older adults while the decision rate intrasubject variability (ISV) was not modulated by age. A significant increase in ISV of the decision rate was confirmed for patients with schizophrenia but not OCD compared to healthy controls. There was no effect of medication on model parameters in the OCD patient group. These results confirm the specificity of the deviance in a simple oculomotor decision process in schizophrenia.

Impaired volitional saccade control: first evidence for a new candidate endophenotype in obsessive-compulsive disorder

Recent research suggests that patients with obsessive-compulsive disorder (OCD) have deficits in the volitional control of saccades. Specific evidence comes from increased latencies of saccadic eye movements when they were volitionally executed but not when they were visually guided. The present study sought to test whether this deviance represents a cognitive endophenotype. To this end, first-degree relatives of OCD patients as genetic risk carriers were compared with OCD patients and healthy controls without a family history of OCD. Furthermore, as volitional response generation comprises selection and initiation of the required response, the study also sought to specify the cognitive mechanisms underlying impaired volitional response generation. Twenty-two unaffected first-degree relatives of OCD patients, 22 unmedicated OCD patients, and 22 healthy comparison subjects performed two types of volitional saccade tasks measuring response selection or only response initiation, respectively. Visually guided saccades were used as a control condition. Our results showed that unaffected first-degree relatives and OCD patients were significantly slowed compared to healthy comparison subjects in volitional response selection. Patients and relatives did not differ from each other. There was no group difference in the visually guided control condition. Taken together, the study provides first evidence that dysfunctional volitional response selection is a candidate endophenotype for OCD.

Saccadic eye movement applications for psychiatric disorders

OBJECTIVE

The study presented here analyzed the patterns of relationship between oculomotor performance and psychopathology, focusing on depression, bipolar disorder, schizophrenia, attention-deficit hyperactivity disorder, and anxiety disorder.

METHODS

Scientific articles published from 1967 to 2013 in the PubMed/Medline, ISI Web of Knowledge, Cochrane, and SciELO databases were reviewed.

RESULTS

Saccadic eye movement appears to be heavily involved in psychiatric diseases covered in this review via a direct mechanism. The changes seen in the execution of eye movement tasks in patients with psychopathologies of various studies confirm that eye movement is associated with the cognitive and motor system.

CONCLUSION

Saccadic eye movement changes appear to be heavily involved in the psychiatric disorders covered in this review and may be considered a possible marker of some disorders. The few existing studies that approach the topic demonstrate a need to improve the experimental paradigms, as well as the methods of analysis. Most of them report behavioral variables (latency/reaction time), though electrophysiological measures are absent.

Antisaccade performance in patients with obsessive-compulsive disorder and unaffected relatives: further evidence for impaired response inhibition as a candidate endophenotype

Cognitive dysfunctions such as inhibitory deficits and visuospatial abnormalities are often found in patients with obsessive-compulsive disorder (OCD). Recent findings in unaffected relatives indicate that response inhibition and other neuropsychological functions may also constitute endophenotypes of OCD. In the present study, 30 OCD patients, 30 first-degree relatives, and 30 healthy control subjects were assessed using a comprehensive neuropsychological test battery. A subsample of 21 subjects of each group also performed an antisaccade task. The samples were matched according to age, gender, education, and verbal intelligence. The OCD patients and the unaffected OCD relatives showed increased antisaccade error rates compared with the healthy control group (p = 0.003, p = 0.028, respectively). Significantly prolonged antisaccade latencies as compared to prosaccade latencies were only found in the OCD patients compared with the healthy control group (p = 0.019). Only OCD patients but not the unaffected OCD relatives were impaired with regard to visuospatial functions, problem-solving, and processing speed. Antisaccade errors did not correlate with severity of OCD or depressive symptoms. This study confirms inhibitory deficits, as indicated by increased antisaccade error rates, as a candidate endophenotype of OCD. In agreement with previous findings from imaging studies, our data suggest that functional abnormalities in frontostriatal and parietal cortical regions form part of the vulnerability for OCD.

A critical review of the contribution of eye movement recordings to the neuropsychology of obsessive compulsive disorder

OBJECTIVE

Dysfunctions of saccadic and/or smooth pursuit eye movements have been proposed as markers of obsessive compulsive disorder (OCD), but experimental results are inconsistent. The aim of this paper was to review the literature on eye movement dysfunctions in OCD to assess whether or not saccades or smooth pursuit may be used to diagnose and characterize OCD.

METHOD

Literature was searched using PubMed, ISI Web of Knowledge, and PsycINFO databases for all studies reporting eye movements in adult patients suffering from OCD.

RESULTS

Thirty-three articles were found. As expected, eye movements of the patients with OCD were mostly assessed with simple oculomotor paradigms involving saccadic and/or smooth pursuit control. In contrast to patients with schizophrenia, however, patients with OCD only displayed rather unspecific deficits, namely slight smooth pursuit impairments and longer response latencies on antisaccade tasks. There was no relationship between these deficits and the severity of patients' symptoms. Interestingly, eye movements of the patients with OCD were almost never recorded during more complex cognitive tasks.

CONCLUSION

As in schizophrenia and autism, eye movement recordings during more complex tasks might help to better characterize the cognitive deficits associated with OCD. Such recordings may reveal specific OCD-related deficits that could be used as reliable diagnostic and/or classification tools.

Impaired inhibitory control is associated with higher-order repetitive behaviors in autism spectrum disorders

BACKGROUND

Impairments in executive cognitive control, including a reduced ability to inhibit prepotent responses, have been reported in autism spectrum disorders (ASD). These deficits may underlie patterns of repetitive behaviors associated with the disorder.

METHOD

Eighteen individuals with ASD and 15 age- and IQ-matched healthy individuals performed an antisaccade task and a visually guided saccade control task, each with gap and overlap conditions. Measures of repetitive behaviors were obtained using the Autism Diagnostic Inventory-Revised (ADI-R) and examined in relation to neurocognitive task performance.

RESULTS

Individuals with an ASD showed increased rates of prosaccade errors (failures to inhibit prepotent responses) on the antisaccade task regardless of task condition (gap/overlap). Prosaccade error rates were associated with the level of higher-order (e.g. compulsions, preoccupations) but not sensorimotor repetitive behaviors in ASD.

CONCLUSIONS

Neurocognitive disturbances in voluntary behavioral control suggest that alterations in frontostriatal systems contribute to higher-order repetitive behaviors in ASD.

The tell-tale tasks: a review of saccadic research in psychiatric patient populations

This review focuses on saccade research with adult psychiatric patients. It begins with an introduction of the various types of saccades and the tasks used to evoke them. The functional significance of the different types of eye movements is briefly discussed. Research findings regarding the saccadic performance of different adult psychiatric patient populations are discussed in detail, with particular emphasis on findings regarding error rates, response latencies, and any specific task parameters that might affect those variables. Findings regarding the symptom, neurocognitive, and neural correlates of saccadic performance and the functional significance of patients' saccadic deficits are also discussed. We also discuss the saccadic deficits displayed by various patient groups in terms of circuitry (e.g. cortical/basal ganglia circuits) that may be implicated in the underlying pathophysiology of several of these disorders. Future directions for research in this growing area are offered.

A review on eye movement studies in childhood and adolescent psychiatry

The neural substrates of eye movement measures are largely known. Therefore, measurement of eye movements in psychiatric disorders may provide insight into the underlying neuropathology of these disorders. Visually guided saccades, antisaccades, memory guided saccades, and smooth pursuit eye movements will be reviewed in various childhood psychiatric disorders. The four aims of this review are (1) to give a thorough overview of eye movement studies in a wide array of psychiatric disorders occurring during childhood and adolescence (attention-deficit/hyperactivity disorder, oppositional deviant disorder and conduct disorder, autism spectrum disorders, reading disorder, childhood-onset schizophrenia, Tourette's syndrome, obsessive compulsive disorder, and anxiety and depression), (2) to discuss the specificity and overlap of eye movement findings across disorders and paradigms, (3) to discuss the developmental aspects of eye movement abnormalities in childhood and adolescence psychiatric disorders, and (4) to present suggestions for future research. In order to make this review of interest to a broad audience, attention will be given to the clinical manifestation of the disorders and the theoretical background of the eye movement paradigms.

Saccade landing point selection and the competition account of pro- and antisaccade generation: The involvement of visual attention ? A review

This paper presents a review and summary of experimental findings on the role of attention in the preparation of saccadic eye movements. The focus is on experiments where performance of prosaccades (saccades towards a suddenly appearing item) and antisaccades (saccades of equal amplitude in the direction opposite to where the target moved) is compared. Evidence suggests that these two opposite responses to the same stimulus event entail competition between neural pathways that generate reflexive movements to the target and neural mechanisms involved in inhibiting the reflex and generating a voluntary gaze shift in the opposite direction to the target appearance. Evidence for such a competition account is discussed in light of a large amount of experimental findings and the overall picture clearly indicates that this competition account has great explanatory power when data on saccadic reaction times and error rates are compared for the two types of saccade. The role of attention is also discussed in particular in light of the finding that the withdrawal of attention by a secondary task 200 to 500 ms before the saccade target appears, leads to speeded antisaccades (without a similar increase in error rates), showing that the results do not simply reflect a speed-accuracy trade-off. This result indicates that the tendency for "reflexive" prosaccades is diminished when attention is engaged in a different task. Furthermore, experiments are discussed that show that as the tendency for a reflexive prosaccade is weakened, antisaccades are speeded up, further supporting the competition account of pro- and antisaccade generation. In the light of evidence from neurophysiology of monkeys and humans, a tentative model of pro- and antisaccade generation is proposed.

Successful multi-site measurement of antisaccade performance deficits in schizophrenia

The antisaccade task is a promising schizophrenia endophenotype; it is stable over time and reflects neurophysiological deficits present in both schizophrenia subjects and their first-degree relatives. Meaningful genetic research requires large sample sizes that are best ascertained using multi-site study designs. To establish the criterion validity of the antisaccade task in a multi-site design, the Consortium on the Genetics of Schizophrenia (COGS) examined whether seven sites could detect previously reported antisaccade deficits in schizophrenia subjects. Investigators presented 3 blocks of 20 antisaccade stimuli to 143 schizophrenia subjects and 195 comparison subjects. Frequent collaborator communication, standardized training, and ongoing quality assurance optimized testing uniformity. Data were discarded from only 1.2% of subjects due to poor quality, reflecting the high fidelity of data collection and scoring methods. All sites detected a significant difference in the proportion of correct antisaccades between schizophrenia and comparison subjects (p<.02 at all sites); group differences in gain and latency were less robust. Regression analyses to adjust for the effects of group, site, age, gender, smoking, and parental education on the proportion of correct antisaccades revealed a significant effect of group, site, and age but no effect of gender, smoking, or parental education, and no group-by-site interactions. Intraclass correlations between proportion of correct antisaccades across the blocks of stimuli ranged from 0.87 to 0.93, demonstrating good within-session reliability at sites. These results confirm previous findings of antisaccade deficits in schizophrenia subjects and support the use of the antisaccade task as a potential schizophrenia endophenotype in multi-site genetic studies.

The antisaccade task as a research tool in psychopathology: a critical review

The antisaccade task is a measure of volitional control of behavior sensitive to fronto-striatal dysfunction. Here we outline important issues concerning antisaccade methodology, consider recent evidence of the cognitive processes and neural mechanisms involved in task performance, and review how the task has been applied to study psychopathology. We conclude that the task yields reliable and sensitive measures of the processes involved in resolving the conflict between volitional and reflexive behavioral responses, a key cognitive deficit relevant to a number of neuropsychiatric conditions. Additionally, antisaccade deficits may reflect genetic liability for schizophrenia. Finally, the ease and accuracy with which the task can be administered, combined with its sensitivity to fronto-striatal dysfunction and the availability of suitable control conditions, may make it a useful benchmark tool for studies of potential cognitive enhancers.

Evidence from increased anticipation of predictive saccades for a dysfunction of fronto-striatal circuits in obsessive-compulsive disorder

In obsessive-compulsive disorder (OCD), a dysfunction of neuronal circuits involving prefrontal areas and the basal ganglia is discussed that implies specific oculomotor deficits. Performance during reflexive and predictive saccades, antisaccades and predictive smooth pursuit was compared between patients with OCD (n=22), patients with schizophrenia (n=21) and healthy subjects (n=24). Eye movements were recorded by infrared reflection oculography. In both patient groups, higher frequencies of anticipatory saccades with reduced amplitudes in the predictive saccade task were observed. Additionally, reduced smooth pursuit eye velocity and increased frequencies of saccadic intrusions during smooth pursuit as well as increased error rates in the antisaccade task were demonstrated for patients suffering from schizophrenia. Patients with OCD and schizophrenia revealed different patterns of oculomotor impairment: whereas increased anticipation of predictive saccades provides evidence for a dysfunction of the circuit between the frontal eye field and the basal ganglia in both groups, results from the antisaccade task imply additional deficits involving the dorsolateral prefrontal cortex in schizophrenic patients. Furthermore, the cortical network for smooth pursuit (especially the frontal eye field) is also assumed to be disturbed in schizophrenia.

Improving antisaccade performance in adolescents with attention-deficit/hyperactivity disorder (ADHD)

The goal of the study was to examine the effects of task manipulations on antisaccade accuracy and response times (RTs) of adolescents with attention-deficit/hyperactivity disorder (ADHD), age-matched controls, 10-year-olds and young adults. Order effects were tested by administering the task at the beginning and end of the session. Other manipulations involved a visual landmark to reduce demands on working memory and internal generation of saccades; spatially specific and non-specific cues at three intervals; and central engagement of attention through perceptual and cognitive means at three intervals. As expected, adolescents with ADHD were impaired relative to age-matched controls in terms of accuracy and saccadic RT on the first administration of the task. Although their accuracy improved with most of the manipulations, it did not improve disproportionately compared to age-matched controls. Nevertheless, with most of the manipulations, they could achieve the same level of accuracy as unaided controls on the first administration of the task. In contrast, the saccadic RTs of the ADHD group came close to normal under several conditions, indicating that elevated antisaccade RTs in this disorder may be related to attentional factors. The ADHD group made more premature saccades and fewer corrective saccades than both the age-matched and younger groups, suggesting difficulties with impulsivity and goal neglect. The findings suggest that cognitive scaffolds can ameliorate at least some of the inhibition deficits in adolescents with ADHD.

Obsessive-compulsive disorder following brain injury: a review

OBJECTIVE

This article reviews obsessive-compulsive disorder (OCD) following acquired brain injury. OCD type symptomatology without any other cognitive, behavioral, or emotional problems following a brain injury appears to be rare. However, the first onset of obsessions and compulsions following a brain injury has been described, but cognitive impairments can potentially color the presentation.

METHOD

This article reviews obsessive-compulsive disorder (OCD) after brain injury, including traumatic brain injury, cerebrovascular accidents, brain tumors and brain infections. Overlapping symtomatology between OCD and brain injury is discussed.

RESULTS

Findings regarding the neuro-imaging of OCD after brain injury are reviewed and integrated with neuropsychological data from studies with idiopathic OCD.

CONCLUSION

There appears to be some convergance between findings from studies of the neuropsychology of idiopathic OCD and neuro-imaging of OCD following brain injury.

A goal activation approach to the study of executive function: An application to antisaccade tasks

We argue that a general control process, responsible for the activation and maintenance of task goals, is central to the concept of executive function. Failures of this process can become manifest as goal neglect: disregard of a task requirement even though it has been understood (Duncan, 1995). We discuss the results of several published and new experiments using various versions of the antisaccade task in order to investigate the circumstances under which goal neglect is likely to occur. Potentially conflicting results in the literature on adaptive control of saccadic eye movements are argued to be attributable to the extent to which different task versions elicit goal neglect. The results suggest an increased susceptibility to goal neglect of high-functioning older adults (Experiment 1) and of first-episode schizophrenia patients (Experiment 2), but not of patients with obsessive-compulsive disorder (Experiment 3). However, the degree to which such differences in susceptibility become manifest in task performance, is shown to be strongly influenced by manipulations of the relative saliency of task requirements. Theoretical and methodological implications for the study of executive function are discussed.

Control of volitional and reflexive saccades in Tourette's syndrome

We hypothesized that Tourette's syndrome (TS) patients would display abnormal control of saccades because of overlap between brain areas suspected in TS pathophysiology and those involved saccade control. Subjects were required to look toward (pro-saccade) or away from (anti-saccade) a visual target. Saccadic reaction times were elevated among TS subjects in all tasks. The occurrence of reflexive pro-saccades in the immediate anti-saccade task was normal, suggesting that the ability to inhibit reflexive saccades was not impaired in TS. However, timing errors (eye movements made prior to GO signal in delayed saccade tasks) were increased in TS indicating that ability to inhibit or delay planned motor programs is significantly impaired in TS.

The cognitive neuropsychiatric approach to investigating the neurobiology of schizophrenia and other disorders

In this paper, we examine a cognitive neuropsychiatric approach to understanding neuropsychiatric disorders by examining recent data in schizophrenia. By understanding and applying this approach, we suggest that the processes underlying the neurobiology of a range of other psychiatric disorders can be understood. Further, an assessment of the brain-behaviour relationships through this emerging discipline provides testable models for further study, using a range of techniques including functional and other imaging techniques.

Parsing cognition in schizophrenia using saccadic eye movements: a selective overview

Eye movements provide a behavioural measure of sensorimotor processing and higher cognitive functions of the brain. With the development of novel paradigms that can be used for the study of various cognitive operations, saccadic eye movements in particular, have become increasingly popular. Patients with schizophrenia have neurocognitive impairments that can be readily investigated with these paradigms. From animal, human lesion and neuroimaging studies, the cerebral centres underlying saccadic eye movements have been identified. The areas of the prefrontal cortex include the dorsolateral prefrontal cortex, the frontal eye fields, the supplementary eye fields, and the anterior cingulate cortex. Pathology of saccadic eye movements, therefore, provides information on the functional status of the underlying neural circuitry in brain disorders such as schizophrenia. In this paper, we evaluate: (i) methodological considerations that are central to the design and application of saccadic paradigms; (ii) brain activation that is associated with saccadic paradigms; (iii) recent findings in healthy subjects and schizophrenic patients; (iv) saccadic abnormalities in other psychiatric and neurological disorders and in individuals at risk for developing schizophrenia.

Altered inhibition of motor responses in Tourette Syndrome and Obsessive-Compulsive Disorder

OBJECTIVES

The Gilles de la Tourette Syndrome (TS) and Obsessive Compulsive Disorder (OCD) have been shown to display impaired cognitive and motor inhibition. This study investigated inhibitory mechanisms of motor responses in order to expand the understanding of sensorimotor integration processes in both disorders. We hypothesized that both patient groups would display altered frontal inhibitory activity.

MATERIAL AND METHODS

To this end event-related brain potentials (ERPs) were recorded in a STOP-paradigm in groups of TS and OCD patients and in a control group. The paradigm required the execution of a motor response after a "go" signal was given and the occasional suppression of this response after a second "stop" signal occurred.

RESULTS

Behavioral parameters and Lateralized Readiness Potential (LRP) confirmed that both patient groups were well able to initiate motor responses. "Go" and "stop" stimuli elicited an enhanced frontal negative activity in both patient groups. In addition, "stop" stimuli were associated with a frontal shift of the NoGo-Anteriorization (NGA) in the TS group but not in the OCD group.

CONCLUSIONS

The data are interpreted to indicate altered frontal inhibitory functions. Similarities and dissimilarities between the findings for TS and OCD are discussed with respect to other pathophysiologic aspects of the disorders.

Neurobiology and clinical pharmacology of obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a brain disorder with recognizable periods of onset, course, familial occurrence, epidemiology, phenomenology, and treatment response. Several manifestations of pathophysiology are beginning to be defined, although they may represent intermediate pathophysiology rather than primary etiology. Positron emission tomography studies have consistently identified hypermetabolism in the orbitofrontal cortex, caudate nucleus, and, sometimes, anterior cingulate cortex. Neuropsychologic testing frequently identifies abnormalities in visuospatial function. Abnormal levels of cerebrospinal fluid neurotransmitters and neuromodulators are identifiable in untreated patients with OCD and return toward normal levels after effective treatment. The most consistent pathophysiologic finding in OCD points toward an abnormality in serotonin neurotransmission. Therapeutic response to selective serotonin reuptake inhibitors and the absence of improvement with norepinephrine reuptake inhibitors and dopamine antagonists argue strongly for a role of serotonin in the pathophysiology and treatment of OCD. Despite this clear indication from treatment trials, probes and manipulations of the serotonin system and its specific receptors have not provided a useful understanding of specific abnormalities. Clomipramine or potent selective serotonin reuptake inhibitors are the pharmacotherapy of choice for OCD, with a more limited role reserved for monoamine oxidase inhibitors. If one selective serotonin reuptake inhibitor is ineffective, others may be beneficial, in addition to the different proserotonergic and nonserotonergic augmentation strategies that could be useful in treatment of resistant OCD patients. Nondrug therapies are also important in OCD: behavioral therapy is frequently helpful and neurosurgery is sometimes helpful when other treatments fail.