Temporal stability of saccadic task performance in schizophrenia and bipolar patients

Antisaccade error rates in first-episode psychosis, ultra-high risk for psychosis and unaffected relatives of schizophrenia: A systematic review and meta-analysis

BACKGROUND

Antisaccade, which is described as looking at the opposite location of the target, is an eye movements paradigm used for assessing cognitive functions in schizophrenia. Initiation and sustainment of saccades in antisaccade are managed by frontal and parietal cortical areas. Antisaccade abnormalities are well-established findings in schizophrenia. However, studies in the early phases of psychotic disorders and clinical/familial risk for psychosis reported inconsistent findings. The current systematic review aimed to review the results of studies investigating antisaccade error rates in first-episode psychosis (FEP), individuals with ultra-high-risk for psychosis (UHRP), and familial-high-risk for psychosis (FHRP) compared to healthy controls.

METHOD

A meta-analysis of 17 studies was conducted to quantitatively review antisaccade errors in FEP, UHR-P and FHRP. The error rate (Hedges'g) was compared between the total of 860 FEP, UHRP, FHRP, and 817 healthy controls. Hedges' g for effect size, I2 for estimating the percentage of variability, and publication bias were evaluated through the R software.

RESULTS

The outcomes of this meta-analysis suggested that FEP is associated with a robust deficit in the antisaccade error rate (g = 1.16, CI = 0.95-1.38). Additionally, both the clinical and familial high-risk groups showed small but significant increases in AS errors (g = 0.26, CI = 0.02-0.52 and g = 0.34, CI = 0.13-0.55, respectively).

CONCLUSION

The large effect size estimated for FEP was compatible with previously reported results in chronic schizophrenia patients. Additionally, relatives had abnormalities with small to medium effect sizes and significant differences. The current findings suggest that antisaccade errors might be a potential endophenotype for psychotic disorders.

Polygenic risk scores for schizophrenia are associated with oculomotor endophenotypes

BACKGROUND

Schizophrenia is a heterogeneous disorder with substantial heritability. The use of endophenotypes may help clarify its aetiology. Measures from the smooth pursuit and antisaccade eye movement tasks have been identified as endophenotypes for schizophrenia in twin and family studies. However, the genetic basis of the overlap between schizophrenia and these oculomotor markers is largely unknown. Here, we tested whether schizophrenia polygenic risk scores (PRS) were associated with oculomotor performance in the general population.

METHODS

Analyses were based on the data of 2956 participants (aged 30-95) of the Rhineland Study, a community-based cohort study in Bonn, Germany. Genotyping was performed on Omni-2.5 exome arrays. Using summary statistics from a recent meta-analysis based on the two largest schizophrenia genome-wide association studies to date, we quantified genetic risk for schizophrenia by creating PRS at different p value thresholds for genetic markers. We examined associations between PRS and oculomotor performance using multivariable regression models.

RESULTS

Higher PRS were associated with higher antisaccade error rate and latency, and lower antisaccade amplitude gain. PRS showed inconsistent patterns of association with smooth pursuit velocity gain and were not associated with saccade rate during smooth pursuit or performance on a prosaccade control task.

CONCLUSIONS

There is an overlap between genetic determinants of schizophrenia and oculomotor endophenotypes. Our findings suggest that the mechanisms that underlie schizophrenia also affect oculomotor function in the general population.

One-year-later spontaneous EEG features predict visual exploratory human phenotypes

During visual exploration, eye movements are controlled by multiple stimulus- and goal-driven factors. We recently showed that the dynamics of eye movements -how/when the eye move- during natural scenes' free viewing were similar across individuals and identified two viewing styles: static and dynamic, characterized respectively by longer or shorter fixations. Interestingly, these styles could be revealed at rest, in the absence of any visual stimulus. This result supports a role of intrinsic activity in eye movement dynamics. Here we hypothesize that these two viewing styles correspond to different spontaneous patterns of brain activity. One year after the behavioural experiments, static and dynamic viewers were called back to the lab to record high density EEG activity during eyes open and eyes closed. Static viewers show higher cortical inhibition, slower individual alpha frequency peak, and longer memory of alpha oscillations. The opposite holds for dynamic viewers. We conclude that some properties of spontaneous activity predict exploratory eye movement dynamics during free viewing.

Antisaccade error rates and gap effects in psychosis syndromes from bipolar-schizophrenia network for intermediate phenotypes 2 (B-SNIP2)

BACKGROUND

Antisaccade tasks can be used to index cognitive control processes, e.g. attention, behavioral inhibition, working memory, and goal maintenance in people with brain disorders. Though diagnoses of schizophrenia (SZ), schizoaffective (SAD), and bipolar I with psychosis (BDP) are typically considered to be distinct entities, previous work shows patterns of cognitive deficits differing in degree, rather than in kind, across these syndromes.

METHODS

Large samples of individuals with psychotic disorders were recruited through the Bipolar-Schizophrenia Network on Intermediate Phenotypes 2 (B-SNIP2) study. Anti- and pro-saccade task performances were evaluated in 189 people with SZ, 185 people with SAD, 96 people with BDP, and 279 healthy comparison participants. Logistic functions were fitted to each group's antisaccade speed-performance tradeoff patterns.

RESULTS

Psychosis groups had higher antisaccade error rates than the healthy group, with SZ and SAD participants committing 2 times as many errors, and BDP participants committing 1.5 times as many errors. Latencies on correctly performed antisaccade trials in SZ and SAD were longer than in healthy participants, although error trial latencies were preserved. Parameters of speed-performance tradeoff functions indicated that compared to the healthy group, SZ and SAD groups had optimal performance characterized by more errors, as well as less benefit from prolonged response latencies. Prosaccade metrics did not differ between groups.

CONCLUSIONS

With basic prosaccade mechanisms intact, the higher speed-performance tradeoff cost for antisaccade performance in psychosis cases indicates a deficit that is specific to the higher-order cognitive aspects of saccade generation.

Working Memory Phenotypes in Early Multiple Sclerosis: Appraisal of Phenotype Frequency, Progression and Test Sensitivity

Working memory (WM) impairments are common and debilitating symptoms of multiple sclerosis (MS), often emerging early in the disease. Predominantly, WM impairments are considered in a binary manner, with patients considered either impaired or not based on a single test. However, WM is comprised of different activated subcomponents depending upon the type of information (auditory, visual) and integration requirements. As such, unique WM impairment phenotypes occur. We aimed to determine the most frequent WM phenotypes in early MS, how they progress and which WM test(s) provide the best measure of WM impairment. A total of 88 participants (63 early relapsing–remitting MS: RRMS, 25 healthy controls) completed five WM tests (visual–spatial, auditory, episodic, executive) as well as the symbol digit modalities test as a measure of processing speed. RRMS patients were followed-up for two years. Factors affecting WM (age/gender/intelligence/mood) and MS factors (disease duration/disability) were also evaluated. Some 61.9% of RRMS patients were impaired on at least one WM subcomponent. The most subcomponents impaired were visual,–spatial and auditory WM. The most common WM phenotypes were; (1) visual–spatial sketchpad + episodic buffer + phonological loop + central executive, (2) visual–spatial sketchpad + central executive. The test of visual–spatial WM provided the best diagnostic accuracy for detecting WM impairment and progression. The SDMT did not achieve diagnostic accuracy greater than chance. Although this may be unsurprising, given that the SDMT is a measure of cognitive processing speed in MS, this does highlight the limitation of the SDMT as a general screening tool for cognitive impairment in early MS.

Attentional engagement and inhibitory control according to positive and negative symptoms in schizophrenia: An emotional antisaccade task

Despite schizophrenia (SZ) is characterized by a high psychopathological heterogeneity, the underlying psychological mechanisms that result in different clinical profiles are unclear. This study examined the cognitive processing of emotional faces (angry, happy, neutral, and sad) by means of assessing inhibitory control (antisaccade task) and attentional engagement (prosaccade task) with the eye-tracking paradigm. Firstly, two clinical SZ subgroups classified according to the predominance of positive (PSZ; n = 20) or negative symptoms (NSZ; n = 34) and a control group of 32 individuals were compared. Secondly, the association between prosaccade and antisaccade measurements and the severity of positive and negative symptoms were analyzed. The PSZ group showed slower antisaccades when angry faces were displayed, and higher positive symptoms were associated with slower prosaccade latencies to ones. Conversely, the NSZ group made overall slower prosaccades with an emotional advantage for angry faces, and higher negative symptoms were associated with faster antisaccade latencies to ones. Hence, whereas positive SZ profile is related to a lack of attentional engagement and an impaired inhibitory control to threatening information; negative SZ profile is linked to a lack of attentional engagement to faces, mainly with non-threat ones, and with an advantage to ignore distracting threatening stimuli. These findings support affective information-processing theories suggesting a hypersensitivity to threat for positive SZ profiles, and a desensitization to socio-emotional information for negative ones. Consequently, characterizing psychological mechanisms of SZ may allow improving current treatments to threat management when positive symptoms are predominant, or emotion sensitization when negative symptoms prevail.

Hypothesis of subcortical visual pathway impairment in schizophrenia

Schizophrenia is a severe mental disease involving both neurological and psychiatric abnormalities. Previous studies mainly focus on damage to high-order cognitive dysfunction, which is related to high-level cortical regions such as the prefrontal and temporal lobes. Recent research reveals that impairment of low-level sensory processing occurs in the early stage of schizophrenia, which may be due to impairment of the subcortical magnocellular visual pathway. Moreover, the structure and function of some important nuclei in a subcortical visual pathway are reported to be abnormal in patients with schizophrenia. Inspired by the above evidence, we propose a hypothesis that impairment of the Superior Colliculus-Pulvinar-Amygdala subcortical visual pathway may be involved in the pathological mechanisms of early stages of schizophrenia. And we propose a possible method to detect dysfunction of this subcortical pathway through examining topological processing, which may help early diagnosis of schizophrenia.

Towards Clinically Relevant Oculomotor Biomarkers in Early Schizophrenia

In recent years, psychiatric research has focused on the evaluation and implementation of biomarkers in the clinical praxis. Oculomotor function deviances are among the most consistent and replicable cognitive deficits in schizophrenia and have been suggested as viable candidates for biomarkers. In this narrative review, we focus on oculomotor function in first-episode psychosis, recent onset schizophrenia as well as individuals at high risk for developing psychosis. We critically discuss the evidence for the possible utilization of oculomotor function measures as diagnostic, susceptibility, predictive, monitoring, and prognostic biomarkers for these conditions. Based on the current state of research we conclude that there are not sufficient data to unequivocally support the use of oculomotor function measures as biomarkers in schizophrenia.

New-Onset Psychosis Associated With a Lesion Localized in the Rostral Tectum: Insights Into Pathway-Specific Connectivity Disrupted in Psychosis

OBJECTIVE

To investigate pathway-specific connectivity disrupted in psychosis.

METHODS

We carried out a case study of a middle-aged patient who presented with new-onset psychosis associated with a space-occupying lesion localized in the right superior colliculus/periaqueductal gray. The study sought to investigate potential connectivity deficits related to the lesion by the use of diffusion tensor imaging and resting-state functional magnetic resonance imaging. To this aim, we generated a functional connectivity map of the patient's brain, centered on the lesion area, and compared this map with the corresponding map of 10 sex- and age-matched control individuals identified from the Max Planck Institute-Leipzig Mind-Brain-Body database.

RESULTS

Our analysis revealed a discrete area in the right rostral tectum, in the immediate vicinity of the lesion, whose activity is inversely correlated with the activity of left amygdala, whereas left amygdala is functionally associated with select areas of the temporal, parietal, and occipital lobes. Based on a comparative analysis of the patient with 10 control individuals, the lesion has impacted on the connectivity of rostral tectum (superior colliculus/periaqueductal gray) with left amygdala as well as on the connectivity of left amygdala with subcortical and cortical areas.

CONCLUSIONS

The superior colliculus/periaqueductal gray might play important roles in the initiation and perpetuation of psychosis, at least partially through dysregulation of left amygdala activity.

Antisaccade and prosaccade eye movements in individuals clinically at risk for psychosis: comparison with first-episode schizophrenia and prediction of conversion

Saccadic eye movements are well-described markers of cerebral function and have been widely studied in schizophrenia spectrum populations. However, less is known about saccades in individuals clinically at risk for schizophrenia. Therefore, we studied individuals in an at-risk mental state (ARMS) (N = 160), patients in their first episode of schizophrenia (N = 32) and healthy controls (N = 75). N = 88 ARMS participants showed an early at-risk mental state (E-ARMS), defined by cognitive-perceptive basic symptoms (COPER) or a combination of risk and loss of function, whereas N = 72 were in a late at-risk mental state (L-ARMS), defined by attenuated psychotic symptoms or brief limited intermittent psychotic symptoms. We examined prosaccades, reflecting overt attentional shifts, and antisaccades, measuring inhibitory control, as well as their relationship as an indicator of the interplay of bottom-up and top-down influences. L-ARMS but not E-ARMS participants had increased antisaccade latencies compared to controls. First-episode patients had higher antisaccade error rates compared to E-ARMS participants and controls, and increased latencies compared to all other groups. Prosaccade latencies did not differ between groups. We observed the expected negative correlation between prosaccade latency and antisaccade error rate, indicating that individuals with shorter prosaccade latencies made more antisaccade errors. The magnitude of the association did not differ between groups. No saccadic measure predicted conversion to psychosis within 2 years. These findings confirm the existence of antisaccade impairments in patients with schizophrenia and provide evidence that volitional response generation in the antisaccade task may be affected even before onset of clinically overt psychosis.

Working Memory and Attention Influence Antisaccade Error Rate in Schizophrenia

Objectives: Antisaccade error rate has been proposed to be one of the most promising endophenotypes for schizophrenia. Increased error rate in patients has been associated with working memory, attention and other executive function impairments. The relationship between antisaccade error rate and other neuropsychological processes in patients compared to healthy controls has not been explored in depth. This study aimed to replicate the finding of heightened antisaccade error rate in patients and determine which cognitive processes were most strongly associated with antisaccade error rate in both patients and controls. In addition, the study investigated whether different antisaccade task paradigms engage different cognitive processes. Methods: One hundred and ninety-one participants (54 patients with schizophrenia/schizoaffective disorder and 137 controls) completed the antisaccade task, which included both gap and step task parameters. Neuropsychological measures were obtained using the MCCB and the Stroop task. Results: The current study replicated a pronounced antisaccade error rate deficit in patients. In patients, working memory variance was most significantly associated with antisaccade errors made during the step condition, while attentional processes were most associated with errors made during the gap condition. In controls, overall global cognitive performance was most associated with antisaccade rates for both gap and step conditions. Conclusions: The current study demonstrates that in schizophrenia patients, but not controls, elevated antisaccade error rate is associated with attention and working memory, but not with global cognitive impairment or psychopathological processes. Our novel findings demonstrate that the gap and step conditions of the antisaccade task engage different cognitive processes. (JINS, 2019, 25, 174-183).

Sensorimotor and executive function slowing in anesthesiology residents after overnight shifts

STUDY OBJECTIVE

Medical residents working overnight call shifts experience sleep deprivation and circadian clock disruption. This leads to deficits in sensorimotor function and increases in workplace accidents. Using quick tablet-based tasks, we investigate whether measureable executive function differences exist following a single overnight call versus routine shift, and whether factors like stress, rest and caffeine affect these measures.

DESIGN

A prospective, observational, longitudinal, comparison study was conducted.

SETTING

An academic tertiary hospital's main operating room suite staffed by attending anesthesiologists, anesthesiology residents, anesthesiologist assistants and nurse anesthetists.

PATIENTS

Subjects were 30 anesthesiology residents working daytime shifts and 30 peers working overnight call shifts from the University of Texas Health Science Center at Houston.

INTERVENTIONS

Before and after their respective work shifts, residents completed the Stanford Sleepiness Scale (SSS) and the ProPoint and AntiPoint tablet-based tasks. These latter tasks are designed to measure sensorimotor and executive functions, respectively.

MEASUREMENTS

The SSS is a self-reported measure of sleepiness. Response times (RTs) are measured in the pointing tasks.

MAIN RESULTS

Call residents exhibited increased RTs across their shifts (post-pre) on both ProPoint (p=0.002) and AntiPoint (p<0.002) tasks, when compared to Routine residents. Increased stress was associated with decreases in AntiPoint RT for Routine (p=0.007), but with greater increases in sleepiness for Call residents (p<0.001). Further, whether or not a Call resident consumed caffeine habitually was associated with ProPoint RT changes; with Call residents who habitually drink caffeine having a greater Pre-Post difference (i.e., more slowing, p<0.001) in ProPoint RT.

CONCLUSIONS

These results indicate that (1) overnight Call residents demonstrate both sensorimotor and cognitive slowing compared to routine daytime shift residents, (2) sensorimotor slowing is greater in overnight Call residents who drink caffeine habitually, and (3) increased stress during a shift reduces (improves) cognitive RTs during routine daytime but not overnight call shifts.

Insights to the schizophrenia continuum: A systematic review of saccadic eye movements in schizotypy and biological relatives of schizophrenia patients

Myles, J.B., S. Rossell, A. Phillipou, Thomas, E and C. Gurvich. A systematic review of saccadic eye movements across the schizophrenia continuum: Characterisation, pathophysiology and genetic associations. NEUROSCI BIOBEHAV REV 21(1) XXX-XXX, 2015. One of the cognitive hallmarks of schizophrenia is impaired eye movements, particularly for the antisaccade task. Less saccade research has been conducted in relation to the broader schizophrenia continuum, that is, people with high schizotypy or first-degree relatives of people with schizophrenia. This systematic review sought to identify, collate and appraise prosaccade, antisaccade and memory-guided saccade studies involving behavioural, neuroimaging and genetic data published between 1980 and September 2016 in individuals with high schizotypy and first-degree relatives. A systematic literature search was conducted, using Ovid MEDLINE, PsycINFO, PubMed and SCOPUS databases. Of 913 references screened, 18 schizotypy, 29 family studies and two schizotypy and relatives articles studies were eligible for inclusion. Antisaccade error rate was the most consistent deficit found for high schizotypy. Relatives had intermediate antisaccade error rates between patients and healthy controls. Results from the limited genetic and neuroimaging studies echoed schizophrenia findings. Confounds were also identified. It was concluded that future research is required to refine the saccade endophenotype and to expand genetic and neuroimaging research.

Rapid-response impulsivity: definitions, measurement issues, and clinical implications

Impulsivity is a multifaceted construct that is a core feature of multiple psychiatric conditions and personality disorders. However, progress in understanding and treating impulsivity is limited by a lack of precision and consistency in its definition and assessment. Rapid-response impulsivity (RRI) represents a tendency toward immediate action that occurs with diminished forethought and is out of context with the present demands of the environment. Experts from the International Society for Research on Impulsivity (InSRI) met to discuss and evaluate RRI measures in terms of reliability, sensitivity, and validity, with the goal of helping researchers and clinicians make informed decisions about the use and interpretation of findings from RRI measures. Their recommendations are described in this article. Commonly used clinical and preclinical RRI tasks are described, and considerations are provided to guide task selection. Tasks measuring two conceptually and neurobiologically distinct types of RRI, "refraining from action initiation" (RAI) and "stopping an ongoing action" (SOA) are described. RAI and SOA tasks capture distinct aspects of RRI that may relate to distinct clinical outcomes. The InSRI group recommends that (a) selection of RRI measures should be informed by careful consideration of the strengths, limitations, and practical considerations of the available measures; (b) researchers use both RAI and SOA tasks in RRI studies to allow for direct comparison of RRI types and examination of their associations with clinically relevant measures; and (c) similar considerations be made for human and nonhuman studies in an effort to harmonize and integrate preclinical and clinical research.

Eye Movement in Unipolar and Bipolar Depression: A Systematic Review of the Literature

BACKGROUND

The analysis of eye movements (EM) by eye-tracking has been carried out for several decades to investigate mood regulation, emotional information processing, and psychomotor disturbances in depressive disorders.

METHOD

A systematic review of all English language PubMed articles using the terms "saccadic eye movements" OR "eye-tracking" AND "depression" OR "bipolar disorders" was conducted using PRISMA guidelines. The aim of this review was to characterize the specific alterations of EM in unipolar and bipolar depression.

RESULTS

Findings regarding psychomotor disturbance showed an increase in reaction time in prosaccade and antisaccade tasks in both unipolar and bipolar disorders. In both disorders, patients have been reported to have an attraction for negative emotions, especially for negative pictures in unipolar and threatening images in bipolar disorder. However, the pattern could change with aging, elderly unipolar patients disengaging key features of sad and neutral stimuli. METHODological limitations generally include small sample sizes with mixed unipolar and bipolar depressed patients.

CONCLUSION

Eye movement analysis can be used to discriminate patients with depressive disorders from controls, as well as patients with bipolar disorder from patients with unipolar depression. General knowledge concerning psychomotor alterations and affective regulation strategies associated with each disorder can also be gained thanks to the analysis. Future directions for research on eye movement and depression are proposed in this review.

Temporal stability and the effects of training on saccade latency in "express saccade makers"

The temporal stability of saccade latency, and the effects of training, particularly in “express saccade makers” (ESMs), has received little attention. ESMs are healthy, naïve, adults, who persist in executing very many low latency “express saccades” (ES; saccades with latency of 80 ms to 130 ms), in conditions designed to suppress such responses. We investigated the stability of ES production (%ES) in 59 ESM and 54 non-ESM participants in overlap tasks. Within a single session, the intraclass correlation coefficient (ICC) for %ES in two runs of 200 trials was 0.97 (p<0.001); participants in whom >30% of saccades over the two runs were ES, were classified as ESMs. For 60 participants tested over two sessions 12 weeks apart, and 30 participants tested in three sessions over approximately six months, the ICC for %ES was uniformly high (0.95, p<0.001 and 0.97, p<0.001 respectively) and participants behaved consistently with their initial classification. Fourteen participants (7 ESMs) were then exposed to training consisting of either gap or overlap tasks. Training increased %ES in both groups. However, when tested in overlap tasks, it was not sufficient to transform Normal participants into ESMs. We conclude that the pattern of saccade behaviour exhibited by ESMs constitutes a stable and distinct oculomotor phenotype.

Cognitive control of gaze in bipolar disorder and schizophrenia

The objective of the present study was to compare two components of executive functioning, response monitoring and inhibition, in bipolar disorder (BP) and schizophrenia (SZ). The saccadic countermanding task is a translational paradigm optimized for detecting subtle abnormalities in response monitoring and response inhibition. We have previously reported countermanding performance abnormalities in SZ, but the degree to which these impairments are shared by other psychotic disorders is unknown. 18 BP, 17 SZ, and 16 demographically matched healthy controls (HC) participated in a saccadic countermanding task. Performance on the countermanding task is approximated as a race between movement generation and inhibition processes; this model provides an estimate of the time needed to cancel a planned movement. Response monitoring was assessed by the reaction time (RT) adjustments based on trial history. Like SZ patients, BP patients needed more time to cancel a planned movement. The two patient groups had equivalent inhibition efficiency. On trial history-based RT adjustments, however, we found a trend towards exaggerated trial history-based slowing in SZ compared to BP. Findings have implications for understanding the neurobiology of cognitive control, for defining the etiological overlap between schizophrenia and bipolar disorder, and for developing pharmacological treatments of cognitive impairments.

Oculomotor executive function abnormalities with increased tic severity in Tourette syndrome

BACKGROUND

Reports conflict as to whether Tourette syndrome (TS) confers deficits in executive function. This study's aim was to evaluate executive function in youths with TS using oculomotor tasks while controlling for confounds of tic severity, age, medication, and severity of comorbid disorders.

METHOD

Four saccade tasks requiring the executive functions of response generation, response inhibition, and working memory (prosaccade, antisaccade, 0-back, and 1-back) were administered. Twenty youths with TS and low tic severity (TS-low), nineteen with TS and moderate tic severity (TS-moderate), and 29 typically developing control subjects (Controls) completed the oculomotor tasks.

RESULTS

There were small differences across groups in the prosaccade task. Controlling for any small sensorimotor differences, TS-moderate subjects had significantly higher error rates than Controls and TS-low subjects in the 0-back and 1-back tasks. In the 1-back task, these patients also took longer to respond than Controls or TS-low subjects.

CONCLUSIONS

In a highly controlled design, the findings demonstrate for the first time that increased tic severity in TS is associated with impaired response inhibition and impaired working memory and that these executive function deficits cannot be accounted for by differences in age, medication or comorbid symptom severity.

Qualitative and quantitative aspects of information processing in first psychosis: latent class analyses in patients, at-risk subjects, and controls

We aimed to determine profiles of information processing deficits in the pathway to first psychosis. Sixty-one subjects at ultrahigh risk (UHR) for psychosis were assessed, of whom 18 converted to a first episode of psychosis (FEP) within the follow-up period. Additionally, 47 FEP and 30 control subjects were included. Using 10 neurophysiological parameters associated with information processing, latent class analyses yielded three classes at baseline. Class membership was related to group status. Within the UHR sample, two classes were found. Transition to psychosis was nominally associated with class membership. Neurophysiological profiles were unstable over time, but associations between specific neurophysiological components at baseline and follow-up were found. We conclude that certain constellations of neurophysiological variables aid in the differentiation between controls and patients in the prodrome and after first psychosis.

Oculomotor inhibitory control in express saccade makers

Express saccade makers (ESMs) produce high proportions (>30 %) of low-latency (80-130 ms) express saccades in tasks in which such responses are usually suppressed. In addition, high directional error rates on the antisaccade (AS) task suggest a failure of oculomotor inhibitory mechanisms in ESMs. However, the AS task is complex and does not provide a measure of inhibitory processes in isolation. We therefore examined inhibitory control in 25 ESM and 28 non-ESM ('Norm') participants, using a minimally delayed oculomotor response (MDOR) task. After a randomised fixation period, a pro-saccade target appeared for 200 or 1,000 ms. Participants were instructed to maintain fixation and saccade to the target position upon target offset. In a control task, they saccaded on target onset. Overall, saccade latency was considerably increased in the MDOR task compared to the control task (354 vs. 170 ms; p < 0.001), and we also observed a latency modulation with display time (200: 399, 1,000: 302 ms; p < 0.001). However, there was no evidence of a difference between groups (p = 0.29). Errors consisted primarily of responses to target onsets and error rates were comparable between the groups (p = 0.33). The overproduction of fast, reflexive responses was still observed in ESMs who generated a higher proportion of their errors within the express latency range (p < 0.001). We confirmed that in the AS task, the ESMs exhibited a higher directional error rate (p = 0.03). These results suggest that the performance 'deficit' observed on the AS task in ESMs cannot be attributed to generally weaker inhibitory control.

Saccadic eye movements in depressed elderly patients

The primary aim of this study was to characterize oculomotor performances in elderly depressed patients. The second aim was to investigate whether cognitive inhibition measured by the antisaccade task was associated with a psychomotor retardation or rather with a more specific cognitive-motor inhibition deficit. Twenty patients with a major depressive disorder and forty-seven healthy subjects performed two eye movement tasks. Saccadic reaction time and error rates were analyzed in the prosaccade task to obtain basic parameters of eye movements. Saccade latency, error rates and correction rates were evaluated in the antisaccade task to investigate inhibition capacities. Performances were impaired in patients, who exhibited a higher reaction time and error rates compared to controls. The higher time cost of inhibition suggested that the reaction time was not related to global psychomotor retardation alone. The higher time cost of inhibition could be explained by a specific alteration of inhibition processes evaluated by the antisaccade task. These changes were associated with the severity of depression. These findings provide a new perspective on cognitive inhibition in elderly depressed patients and could have important clinical implications for our understanding of critical behaviors involving deficits in inhibitory processes in the elderly.

Attention orienting and inhibitory control across the different mood states in bipolar disorder: an emotional antisaccade task

An antisaccade experiment, using happy, sad, and neutral faces, was conducted to examine the effect of mood-congruent information on inhibitory control (antisaccade task) and attentional orienting (prosaccade task) during the different episodes of bipolar disorder (BD) - manic (n=22), depressive (n=25), and euthymic (n=24). A group of 28 healthy controls was also included. Results revealed that symptomatic patients committed more antisaccade errors than healthy individuals, especially with mood-congruent faces. The manic group committed more antisaccade errors in response to happy faces, while the depressed group tended to commit more antisaccade errors in response to sad faces. Additionally, antisaccade latencies were slower in BD patients than in healthy individuals, whereas prosaccade latencies were slower in symptomatic patients. Taken together, these findings revealed the following: (a) slow inhibitory control in BD patients, regardless of their episode (i.e., a trait), and (b) impaired inhibitory control restricted to symptomatic patients (i.e., a state).

Evidence of cognitive dysfunction after soccer playing with ball heading using a novel tablet-based approach

Does frequent head-to-ball contact cause cognitive dysfunctions and brain injury to soccer players? An iPad-based experiment was designed to examine the impact of ball-heading among high school female soccer players. We examined both direct, stimulus-driven, or reflexive point responses (Pro-Point) as well as indirect, goal-driven, or voluntary point responses (Anti-Point), thought to require cognitive functions in the frontal lobe. The results show that soccer players were significantly slower than controls in the Anti-Point task but displayed no difference in Pro-Point latencies, indicating a disruption specific to voluntary responses. These findings suggest that even subconcussive blows in soccer can result in cognitive function changes that are consistent with mild traumatic brain injury of the frontal lobes. There is great clinical and practical potential of a tablet-based application for quick detection and monitoring of cognitive dysfunction.

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.

Antisaccades as a follow-up tool in major depressive disorder therapies: a pilot study

Eight patients with major depression, included in a double-blind study, performed an antisaccade task. Results suggested a link between antisaccade performances and clinical scale scores in patients who respond to therapy. Moreover, error rates may well predict response from day of inclusion, thus serving as a state-marker for mood disorders.

Saccadic performance and cortical excitability as trait-markers and state-markers in rapid cycling bipolar disorder: a two-case follow-up study

BACKGROUND

The understanding of physiopathology and cognitive impairments in mood disorders requires finding objective markers. Mood disorders have often been linked to hypometabolism in the prefrontal dorsolateral cortex, and to GABAergic and glutamatergic neurotransmission dysfunction. The present study aimed to discover whether saccadic tasks (involving DPLFC activity), and cortical excitability (involving GABA/Glutamate neurotransmission) could provide neuropsychophysical markers for mood disorders, and/or of its phases, in patients with rapid cycling bipolar disorders (rcBD).

METHODS

Two rcBD patients were followed for a cycle, and were compared to nine healthy controls. A saccade task, mixing prosaccades, antisaccades, and nosaccades, and an evaluation of cortical excitability using transcranial magnetic stimulation were performed.

RESULTS

We observed a deficit in antisaccade in patients independently of thymic phase, and in nosaccade in the manic phase only. Cortical excitability data revealed global intracortical deficits in all phases, switching according to cerebral hemisphere and thymic phase.

CONCLUSION

Specific patterns of performance in saccade tasks and cortical excitability could characterize mood disorders (trait-markers) and its phases (state-markers). Moreover, a functional relationship between oculometric performance and cortical excitability is discussed.

Reflexive and volitional saccades: biomarkers of Huntington disease severity and progression

BACKGROUND

Huntington disease (HD) is a genetic, neurodegenerative disorder characterized by chorea, behavioral co-morbidities, cognitive deficits, and eye movement abnormalities. We sought to evaluate whether reflexive and voluntary orienting prove useful as biomarkers of disease severity in HD.

METHODS

Eleven HD subjects were evaluated with the motor subscale of the Unified Huntington Disease Rating Scale (UHDRS) and the Montreal Cognitive Assessment. Using an infrared eye tracker, we also measured latency and error rates of horizontal and vertical saccades using prosaccade and antisaccade eye movement tasks. We calculated simple and age-controlled correlations between eye movement and clinical parameters.

RESULTS

Prosaccade latency correlated with total chorea score. HD patients with greater clinical severity were significantly slower in the prosaccade task. Antisaccade error rate also correlated with UHDRS motor score and total chorea score. HD patients with greater clinical severity as measured by either measure made significantly more errors in the antisaccade task. All these correlations remained significant even when age was taken into account.

CONCLUSIONS

The results of the present age-controlled study show for the first time that both reflexive and voluntary eye motor control in HD patients decrease with increase in disease severity suggesting declines in both motor and cognitive function. Thus, relatively simple eye movement parameters (latency and error rate) obtained from simple tasks (prosaccade and antisaccade) may serve as quantitative biomarkers of sub-cortical and cortical disease severity in HD and could aid in predicting onset, distinguishing subtypes, or evaluating disease progression and novel therapies.

Effects of haloperidol on cognition in schizophrenia patients depend on baseline performance: a saccadic eye movement study

Schizophrenic patients are heterogeneous with respect to voluntary eye movement performance, with some showing impairment (e.g., high antisaccade error rates) and others having intact performance. To investigate how this heterogeneity may correlate with different cognitive outcomes after treatment, we used a prosaccade and antisaccade task to investigate the effects of haloperidol in schizophrenic subjects at three time points: baseline (before medication), 3-5 days post-medication, and 12-14 days post-medication. We also investigated changes on the Stroop Task and the Positive and Negative Syndrome Scale (PANSS) in these same subjects. Results were compared to matched controls. When considered as a single patient group, haloperidol had no effects across sessions on reflexive and voluntary saccadic eye movements of schizophrenic patients. In contrast, the performance of the Control group improved slightly but significantly across sessions on the voluntary eye movement task. When each subject was considered separately, interestingly, for schizophrenic patients change in voluntary eye movement performance across sessions depended on the baseline performance in a non-monotonic manner. That is, there was maximal worsening of voluntary eye movement performance at an intermediate level of baseline performance and the worsening decreased on either side of this intermediate baseline level. When patients were divided into categorical subgroups (nonimpaired and impaired), consistent with the non-monotonic relationship, haloperidol worsened voluntary eye movement performance in the nonimpaired patients and improved performance in the impaired patients. These results were only partially reflected in the Stroop Test. Both patient subgroups showed clinically significant improvement over time as measured by the PANSS. These findings suggest that haloperidol has different effects on cognitive performance in impaired and nonimpaired schizophrenic patients that are not evident in clinical ratings based on the PANSS. Given that good cognitive function is important for long-term prognosis and that there is heterogeneity in schizophrenia, these findings are critical for optimal evaluation and treatment of schizophrenic patients.

Response switching in schizophrenia patients and healthy subjects: effects of the inter-response interval

Schizophrenia patients show impaired saccadic response switching, pointing to action control deficits at the level of response selection. Previous studies on healthy subjects suggested that response switch effects might decrease if the prior response is longer ago, reflecting a slow dissipation of the response program persisting from the previous trial. The present study aimed at directly investigating whether response switch effects in schizophrenia patients and healthy subjects depend on the inter-response interval (IRI). Effects of response switching on pro- and antisaccade performance were analyzed in 19 schizophrenia patients and 19 healthy controls at 3 different IRIs (2,500, 3,000, 4,000 ms). Response switch effects of healthy subjects did not vary with the IRI, suggesting that the previous response program persists as long as no contrary response program is activated. In schizophrenia, response switch deficits were replicated at an IRI of 3,000 ms, whereas at IRIs of 2,500 and 4,000 ms, effects of response switching did not significantly differ from healthy subjects. This might suggest that there is a specific IRI range particularly sensitive to response switch deficits in schizophrenia. However, effects of response switching at different IRIs remain to be consolidated.

Antisaccade performance is related to genetic loading for schizophrenia

Disturbances of the oculomotor system are promising endophenotypes for schizophrenia. Increased error rates in the antisaccade task and prolonged antisaccade latencies have been found in patients with schizophrenia and their first degree relatives. We investigated oculomotor performance in 41 parents of schizophrenia patients and 22 controls with a prosaccade task and an antisaccade task. Parents were grouped into parents with a positive family history for schizophrenia (N=9) and parents with a negative family history for schizophrenia (N=32). An overlap-paradigm was applied; eye movements were recorded using infrared oculography. The combined group of parents made more antisaccade direction errors than controls (p=0.005) and there was a linear increase in direction errors from controls via negative family history parents to positive family history parents (p=0.008). Antisaccade latencies were prolonged in the combined parent group (p=0.057) compared to controls and there was a linear increase in latency with genetic loading (p=0.018). No group differences were found for prosaccade parameters. These results support the hypothesis that antisaccade impairment is associated with genetic loading for schizophrenia.

Pharmacological treatment effects on eye movement control

The increasing use of eye movement paradigms to assess the functional integrity of brain systems involved in sensorimotor and cognitive processing in clinical disorders requires greater attention to effects of pharmacological treatments on these systems. This is needed to better differentiate disease and medication effects in clinical samples, to learn about neurochemical systems relevant for identified disturbances, and to facilitate identification of oculomotor biomarkers of pharmacological effects. In this review, studies of pharmacologic treatment effects on eye movements in healthy individuals are summarized and the sensitivity of eye movements to a variety of pharmacological manipulations is established. Primary findings from these studies of healthy individuals involving mainly acute effects indicate that: (i) the most consistent finding across several classes of drugs, including benzodiazepines, first- and second- generation antipsychotics, anticholinergic agents, and anticonvulsant/mood stabilizing medications is a decrease in saccade and smooth pursuit velocity (or increase in saccades during pursuit); (ii) these oculomotor effects largely reflect the general sedating effects of these medications on central nervous system functioning and are often dose-dependent; (iii) in many cases changes in oculomotor functioning are more sensitive indicators of pharmacological effects than other measures; and (iv) other agents, including the antidepressant class of serotonergic reuptake inhibitors, direct serotonergic agonists, and stimulants including amphetamine and nicotine, do not appear to adversely impact oculomotor functions in healthy individuals and may well enhance aspects of saccade and pursuit performance. Pharmacological treatment effects on eye movements across several clinical disorders including schizophrenia, affective disorders, attention deficit hyperactivity disorder, Parkinson's disease, and Huntington's disease are also reviewed. While greater recognition and investigation into pharmacological treatment effects in these disorders is needed, both beneficial and adverse drug effects are identified. This raises the important caveat for oculomotor studies of neuropsychiatric disorders that performance differences from healthy individuals cannot be attributed to illness effects alone. In final sections of this review, studies are presented that illustrate the utility of eye movements for use as potential biomarkers in pharmacodynamic and pharmacogenetic studies. While more systematic studies are needed, we conclude that eye movement measurements hold significant promise as tools to investigate treatment effects on cognitive and sensorimotor processes in clinical populations and that their use may be helpful in speeding the drug development pathway for drugs targeting specific neural systems and in individualizing pharmacological treatments.

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.

The effect of change in clinical state on eye movement dysfunction in schizophrenia

Measures of eye movement dysfunction have been considered as candidate endophenotypes for the study of genetic liability in schizophrenia. In this respect it is crucial to confirm a clinical state independentce of these measures. Twenty people with DSM-IV schizophrenia were assessed using a battery of oculomotor tasks in the acute phase of their disorder without being treated with antipsychotic medication and then again in the remission phase under treatment with antipsychotic medication. The saccade latency in the saccade task, the error rate and antisaccade latency in the antisaccade task, and the frequency of unwanted saccades in the active fixation task were stable in time both at the group level and within each individual, showing no relation to the significant improvement in different psychopathological dimensions of these patients. The root mean square error, gain and saccade frequency in the pursuit task were not stable over time, although again this instability was not related to the changes in psychopathological status of these patients. Finally, the saccade frequency in the active fixation task with distracters was not stable in time and was correlated with changes in specific dimensions of psychopathology. These results provide further evidence that saccade and smooth eye pursuit dysfunction measures are not affected by the substantial change in the clinical state of schizophrenia from the acute phase to remission, and strengthen the current view that they can be used as endophenotypes. On the other hand, active fixation might be state-dependent adding to the evidence against its use as a candidate endophenotype in schizophrenia.

Oculomotor and neuropsychological effects of antipsychotic treatment for schizophrenia

Cognitive enhancement has become an important target for drug therapies in schizophrenia. Treatment development in this area requires assessment approaches that are sensitive to procognitive effects of antipsychotic and adjunctive treatments. Ideally, new treatments will have translational characteristics for parallel human and animal research. Previous studies of antipsychotic effects on cognition have relied primarily on paper-and-pencil neuropsychological testing. No study has directly compared neurophysiological biomarkers and neuropsychological testing as strategies for assessing cognitive effects of antipsychotic treatment early in the course of schizophrenia. Antipsychotic-naive patients with schizophrenia were tested before treatment with risperidone and again 6 weeks later. Matched healthy participants were tested over a similar time period. Test-retest reliability, effect sizes of within-subject change, and multivariate/univariate analysis of variance were used to compare 3 neurophysiological tests (visually guided saccade, memory-guided saccade, and antisaccade) with neuropsychological tests covering 4 cognitive domains (executive function, attention, memory, and manual motor function). While both measurement approaches showed robust neurocognitive impairments in patients prior to risperidone treatment, oculomotor biomarkers were more sensitive to treatment-related effects on neurocognitive function than traditional neuropsychological measures. Further, unlike the pattern of modest generalized cognitive improvement suggested by neuropsychological measures, the oculomotor findings revealed a mixed pattern of beneficial and adverse treatment-related effects. These findings warrant further investigation regarding the utility of neurophysiological biomarkers for assessing cognitive outcomes of antipsychotic treatment in clinical trials and in early-phase drug development.

Reduced attentional engagement contributes to deficits in prefrontal inhibitory control in schizophrenia

BACKGROUND

Problems with the voluntary control of behavior, such as those leading to increased antisaccade errors, are accepted as evidence of prefrontal dysfunction in schizophrenia. We previously reported that speeded prosaccade responses, i.e., shorter response latencies for automatic shifts of attention to visual targets, were associated with higher antisaccade error rates in schizophrenia. This suggests that dysregulation of automatic attentional processes may contribute to disturbances in prefrontally mediated control of voluntary behavior.

METHODS

Twenty-four antipsychotic-naïve schizophrenia patients and 30 healthy individuals completed three tasks: a no-gap prosaccade task in which subjects shifted gaze toward a peripheral target that appeared coincident with the disappearance of a central fixation target and separate prosaccade and antisaccade tasks in which a temporal gap or overlap of the central target offset and peripheral target onset occurred. Sixteen patients were retested after 6 weeks of antipsychotic treatment.

RESULTS

Patients' prosaccade latencies in the no-gap task were speeded compared with healthy individuals. While patients were not atypical in the degree to which response latencies were speeded or slowed by the gap and overlap manipulations, those patients with diminished attentional engagement on the prosaccade task (i.e., reduced overlap effect) had significantly elevated antisaccade error rates. This effect persisted in patients evaluated after antipsychotic treatment.

CONCLUSIONS

This study provides evidence that a reduced ability to engage attention may render patients more distracted by sensory inputs, thereby further compromising impaired executive control during antisaccade tasks. Thus, alterations in attentional and executive control functions can synergistically disrupt voluntary behavioral responses in schizophrenia.

Schizoaffective disorder: diagnostic issues and future recommendations

OBJECTIVE

Difficulties surrounding the classification of mixed psychotic and affective syndromes continue to plague psychiatric nosology. This paper addresses the controversy regarding the diagnostic validity of schizoaffective disorder (SAD), a diagnosis that is used in both DSM-IV and ICD-10 and one that encroaches on both schizophrenia (SCZ) and bipolar disorder (BD).

METHODS

A systematic synthesis of clinical and empirical literature, including evidence from cognitive, neurobiological, genetic, and epidemiological research, was undertaken with the aim of evaluating the utility of the SAD classification.

RESULTS

Distinctions between the diagnostic categories of SCZ, SAD and BD are not clearly demarcated by findings from neuropsychological, neuroimaging, molecular neurobiology, or genetic epidemiology studies. On the contrary, convergent evidence purports overlap across current diagnostic boundaries in the heritability and pathophysiology of psychotic and affective disorders. However, there are some disorder-specific findings.

CONCLUSIONS

Schizoaffective disorder is a prototypic boundary condition that epitomizes the pitfalls of the current categorical classification system. Future revisions to the DSM should consider the implementation of one of two alternative models to account for individuals presenting with mixed psychotic and affective symptoms. These include the views that (i) SAD is a comorbid set of symptoms that occur as a by-product of two separate disorders (SCZ and BD) or, that (ii) SAD exists as the mid-point on a continuum between SCZ and BD, such that the incorporation of these two disorders onto one dimension may be a suitable alternative. Hence the category SAD should be omitted in future revisions of DSM, allowing the development of meaningful nomenclature that rests upon further rigorous investigation of differences and similarities between disorders.

Searching for unique endophenotypes for schizophrenia and bipolar disorder within neural circuits and their molecular regulatory mechanisms

The endophenotype is a construct that has utility for the study of postmortem brains from patients with psychotic disorders. By identifying networks of genes that show changes in expression within specific neuronal populations implicated in the pathophysiology of schizophrenia and bipolar disorder, it may be possible to move toward understanding these disorders at the cellular and molecular levels. The ultimate goal is to characterize their respective underlying genotypes.

Neurophysiological endophenotypes of schizophrenia: the viability of selected candidate measures

In an effort to reveal susceptibility genes, schizophrenia research has turned to the endophenotype strategy. Endophenotypes are characteristics that reflect the actions of genes predisposing an individual to a disorder, even in the absence of diagnosable pathology. Individual endophenotypes are presumably determined by fewer genes than the more complex phenotype of schizophrenia and would, therefore, reduce the complexity of genetic analyses. Unfortunately, despite there being rational criteria to define a viable endophenotype, the term is sometimes applied indiscriminately to characteristics that are deviant in affected individuals. Schizophrenia patients exhibit deficits in several neurophysiological measures of information processing that have been proposed as candidate endophenotypes. Successful processing of sensory inputs requires the ability to inhibit intrinsic responses to redundant stimuli and, reciprocally, to facilitate responses to less frequent salient stimuli. There is evidence to suggest that both these processes are "impaired" in schizophrenia. Measures of inhibitory failure include prepulse inhibition of the startle reflex, P50 auditory evoked potential suppression, and antisaccade eye movements. Measures of impaired deviance detection include mismatch negativity and the P300 event-related potential. The purpose of this review is to systematically evaluate the endophenotype candidacy of these key neurophysiological abilities. For each candidate, we describe typical experimental procedures, the current understanding of the underlying neurobiology, the nature of the abnormality in schizophrenia, the reliability, stability and heritability of the measure, and any reported gene associations. We conclude with a discussion of the few studies thus far that have employed a multivariate approach with these candidates.

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.

Saccadic performance in questionnaire-identified schizotypes over time

In the present study, 121 young adults (mean age=19 years), hypothesized to be at varying levels of risk for psychosis on the basis of their psychometric profiles, were administered saccadic (antisaccade and refixation) tasks at two separate assessments. At Time 1, individuals posited to be at heightened risk for the later development of schizophrenia-spectrum disorders (i.e., those individuals with elevated Social Anhedonia Scale [SAS] scores) produced significantly more antisaccade task errors than the controls. Despite apparent improvement in antisaccade task performance from initial testing to the follow-up (mean test-retest interval=59 months) across all groups, the Social Anhedonia (SocAnh) group continued to produce significantly more errors than the control group. The antisaccade task performance of the control group showed good temporal stability (Pearson's r=0.70, ICC=0.52), and the SocAnh group's performance showed excellent temporal stability (Pearson's r=0.85, ICC=0.83). The results of this investigation are twofold: First, antisaccade task performance is temporally stable, even in psychometrically identified schizotypes over long test-retest intervals; and secondly, Social Anhedonia Scale scores as well as Time 1 antisaccade task accuracy accounted for much of the variability in Time 2 antisaccade task performance. These findings add to the growing body of literature suggesting that antisaccade task deficits may serve as an endophenotypic marker of a schizophrenia diathesis.