Task In Schizophrenia Research Articles

Abnormal Brain Activation During Theory of Mind Tasks in Schizophrenia: A Meta-Analysis.

Social cognition abilities are severely impaired in schizophrenia (SZ). The current meta-analysis used foci of 21 individual studies on functional abnormalities in the schizophrenic brain in order to identify regions that reveal convergent under- or over-activation during theory of mind (TOM) tasks. Studies were included in the analyses when contrasting tasks that require the processing of mental states with tasks which did not. Only studies that investigated patients with an ICD or DSM diagnosis were included. Quantitative voxel-based meta-analyses were done using Seed-based d Mapping software. Common TOM regions like medial-prefrontal cortex and temporo-parietal junction revealed abnormal activation in schizophrenic patients: Under-activation was identified in the medial prefrontal cortex, left orbito-frontal cortex, and in a small section of the left posterior temporo-parietal junction. Remarkably, robust over-activation was identified in a more dorsal, bilateral section of the temporo-parietal junction. Further abnormal activation was identified in medial occipito-parietal cortex, right premotor areas, left cingulate gyrus, and lingual gyrus. The findings of this study suggest that SZ patients simultaneously show over- and under-activation in TOM-related regions. Especially interesting, temporo-parietal junction reveals diverging activation patterns with an under-activating left posterior and an over-activating bilateral dorsal section. In conclusion, SZ patients show less specialized brain activation in regions linked to TOM and increased activation in attention-related networks suggesting compensatory effects.

Exploring non-stationarity patterns in schizophrenia: neural reorganization abnormalities in the alpha band

Objective. The aim of this paper was to characterize brain non-stationarity during an auditory oddball task in schizophrenia (SCH). The level of non-stationarity was measured in the baseline and response windows of relevant tones in SCH patients and healthy controls. Approach. Event-related potentials were recorded from 28 SCH patients and 51 controls. Non-stationarity was estimated in the conventional electroencephalography frequency bands by means of Kullback–Leibler divergence (KLD). Relative power (RP) was also computed to assess a possible complementarity with KLD. Main results. Results showed a widespread statistically significant increase in the level of non-stationarity from baseline to response in all frequency bands for both groups. Statistically significant differences in non-stationarity were found between SCH patients and controls in beta-2 and in the alpha band. SCH patients showed more non-stationarity in the left parieto-occipital region during the baseline window in the beta-2 band. A leave-one-out cross validation classification study with feature selection based on binary stepwise logistic regression to discriminate between SCH patients and controls provided a positive predictive value of 72.73% and negative predictive value of 78.95%. Significance. KLD can characterize transient neural reorganization during an attentional task in response to novelty and relevance. Our findings suggest anomalous reorganization of neural dynamics in SCH during an oddball task. The abnormal frequency-dependent modulation found in SCH patients during relevant tones is in agreement with the hypothesis of aberrant salience detection in SCH. The increase in non-stationarity in the alpha band during the active task supports the notion that this band is involved in top-down processing. The baseline differences in the beta-2 band suggest that hyperactivation of the default mode network during attention tasks may be related to SCH symptoms. Furthermore, the classification improved when features from both KLD and RP were used, supporting the idea that these measures can be complementary.

Effects of chronic antipsychotic treatment on neurophysiological correlates of the auditory oddball task in schizophrenia: A preliminary report from a multicentre study

IntroductionThe effects of chronic antipsychotic administration on the human brain are debated. In particular, first-generation (FGAs) and second-generation antipsychotics (SGAs) seem to have different impacts on brain function and structure in subjects with schizophrenia. Few studies have investigated the effect of chronic administration of FGAs and SGAs on indices of brain function, such as event-related potentials (ERP) or neuropsychological performance.ObjectivesWithin the Italian Network for Research on Psychoses study, subjects stabilized on FGAs or SGAs were compared on P300, an ERP component, thought to reflect attention, working memory and context integration and on neurocognitive indices.MethodsERPs were recorded in 110 chronic, stabilized patients with Schizophrenia (28 used FGAs) during a standard auditory oddball task. P300 latency and amplitude were assessed at Pz channel. MATRICS Consensus Cognitive Battery (MCCB) was used for cognitive assessment.ResultsCompared with the SGAs group, patients on FGAs showed significant increased P300 latency (P = 0.003; Cohen's d = 0.67) and significant decreased P300 amplitudes (P = 0.023; Cohen's d = 0.38). The two groups did not differ on psychopathology and MCCB scores. Multiple linear regressions revealed that “FGAs vs. SGAs” (β = 0.298, P = 0.002) and MCCB neurocognitive composite T-score (β = –0.273, P = 0.004) were independent predictors of P300 latency, whereas only age (β = –0.220, P = 0.027) was an independent predictor of P300 amplitude.ConclusionsFGAs seem to affect the functional brain activity more than SGAs, particularly slowing cortical processing. Our results suggest that discrepant findings concerning P300 latency in schizophrenia might be related to the type of antipsychotic treatment used. Longitudinal studies are needed to further address this issue.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Electrophysiological correlates of adaptive control and attentional engagement in patients with first episode schizophrenia and healthy young adults.

The goal of this study was to investigate the neural dynamics of error processing and post-error adjustments in cognitive control and attention to a cognitive task in schizophrenia. We adopted a time-frequency approach in order to examine activity in the theta and alpha frequency bands as indices of cognitive control and attentional engagement. The results showed that error processing was characterized by increases in theta-band activity, accompanied by decreases in alpha-band activity, in both healthy control participants and participants with schizophrenia. However, both the theta and alpha effects were significantly reduced in participants with schizophrenia. Post-error increases in theta activity were associated with improved accuracy on subsequent trials in control participants but not in participants with schizophrenia. In addition, increases in alpha-band activity were found in the prestimulus period before partial attention lapses, but only for control participants and participants with schizophrenia with relatively low positive symptom severity. These results provide evidence for a deficit in cognitive control mechanisms mediated by midfrontal theta activity in schizophrenia, and suggest a particularly pronounced deficit in patients' ability to engage adaptive control mechanisms following errors. Our results also indicate that partial attention lapses can be indexed in both control participants and participants with schizophrenia by increases in alpha activity, but that in schizophrenia this varies as a function of positive symptom severity. We suggest that disrupted theta-band function represents a key deficit of schizophrenia, whereas disruptions in the alpha band may be the byproduct of atypically regulated attention.

SU73. Childhood Trauma-Related Alterations in Brain Function During a Theory-of-Mind (ToM) Task in Schizophrenia

SU73. Childhood Trauma-Related Alterations in Brain Function During a Theory-of-Mind (ToM) Task in Schizophrenia

Childhood trauma-related alterations in brain function during a Theory-of-Mind task in schizophrenia

Childhood trauma is a risk factor for schizophrenia that affects brain functions associated with higher cognitive processes, including social cognition. Alterations in Theory-of-Mind (ToM), or mentalizing skills, are a hallmark feature of schizophrenia, and are also evident in individuals exposed to childhood trauma. However, the impact of childhood trauma exposure on brain function during social cognition in schizophrenia remains unclear. We thus examined the association between childhood trauma and brain function during the performance of a ToM task in 47 patients diagnosed with schizophrenia or schizoaffective disorder. All participants completed the Childhood Trauma Questionnaire (CTQ) and underwent functional magnetic resonance imaging while performing an established visual-cartoon affective ToM task. Whole-brain multiple regression analysis was performed on ToM-related brain activation, with CTQ total score as regressor of interest, while accounting for the effects of age, sex, diagnosis, symptom severity, behavioural performance, intelligence and medications levels. First, using a small-volume correction approach within a mask made of key regions for ToM [including bilateral temporo-parietal junctions (TPJ), medial prefrontal cortex (mPFC) and posterior cingulate cortex (PCC)/precuneus], total CTQ scores were positively associated with activation of the PCC/precuneus. Second, exploratory analyses for the rest of the brain (i.e., ROIs masked-out), revealed a positive association between trauma exposure and activation of the dorsomedial prefrontal cortex (dmPFC), and a negative association with activation of the anterior section of the TPJ. These results suggest that childhood trauma exposure may, at least partially, contribute to functional alterations of brain regions essential for effective mental state inference in schizophrenia.

A Computer-Aided Diagnosis System With EEG Based on the P3b Wave During an Auditory Odd-Ball Task in Schizophrenia

To design a Computer-aided diagnosis (CAD) system using an optimized methodology over the P3b wave in order to objectively and accurately discriminate between healthy controls (HC) and schizophrenic subjects (SZ). We train, test, analyze, and compare various machine learning classification approaches optimized in terms of the correct classification rate (CCR), the degenerated Youden's index (DYI) and the area under the receiver operating curve (AUC). CAD system comprises five stages: electroencephalography (EEG) preprocessing, feature extraction, seven electrode groupings, discriminant feature selection, and binary classification. With two optimal combinations of electrode grouping, filtering, feature selection algorithm, and classification machine, we get either a mean CCR = 93.42%, specificity = 0.9673, sensitivity = 0.8727, DYI = 0.9188, and AUC = 0.9567 (total-15Hz-J5-MLP), or a mean CCR = 92.23%, specificity = 0.9499, sensitivity = 0.8838, DYI = 0.9162, and AUC = 0.9807 (right hemisphere-35Hz-J5-SVM), which to our knowledge are higher than those available to date. We have verified that a more restrictive low-pass filtering achieves higher CCR as compared to others at higher frequencies in the P3b wave. In addition, results validate previous hypothesis about the importance of the parietal-temporal region, associated with memory processing, allowing us to identify powerful {feature,electrode} pairs in the diagnosis of schizophrenia, achieving higher CCR and AUC in classification of both right and left Hemispheres, and parietal-temporal EEG signals, like, for instance, the {PSE, P4} pair (J5 and mutual information feature selection). Diagnosis of schizophrenia is made thoroughly by psychiatrists but as any human-based decision that has a subjective component. This CAD system provides the human expert with an objective complimentary measure to help him in diagnosing schizophrenia.

Fonctions cognitives sous-jacentes aux déficits de fluence verbale dans la schizophrénie : revue de la littérature

Individuals with schizophrenia usually show impairment on various cognitive functions, including long-term memory, executive functions and language. Compared to healthy controls, their performance is impaired in verbal fluency tests. These tests require participants to generate in a given time as many words as they can, belonging to a given category (semantic fluency), or beginning with a specific letter (orthographic fluency). Various cognitive functions are involved in verbal fluency tests: psychomotor speed, executive functions, language, long-term verbal memory and semantic memory. The purpose of the present study was to clarify the functional origin of verbal fluency deficits in schizophrenia through a literature review. Nineteen articles were selected in Pubmed and PsycINFO after initial screening and detailed review. They were formally analyzed with regard to general performance, cognitive strategies used in semantic and orthographic fluency tests and, underlying cognitive origin of deficits. Results show that individuals with schizophrenia produce fewer words than healthy controls in both types of fluency tests. Their impairment is more apparent in semantic than in orthographic fluency tests. Results of studies reviewed also show that individuals with schizophrenia adopt the same clustering (i.e. production of related words within a subcategory) and switching (i.e. ability to shift between clusters when a subcategory is exhausted) strategies than healthy controls, but less efficiently. Several hypotheses, such as the impairment of executive functions, semantic memory or speed of information processing, were put forward to account for this finding. Interestingly, the few studies in which researchers performed an analysis of the semantic relationships between words produced in fluency tests showed a less semantic coherence among people with schizophrenia than in healthy controls. Such a difference could be explained by disorganization of semantic memory or impairment in the activation of conceptual representations in semantic memory. Studies in which correlations and regression analyzes were performed allow for clarifying the cognitive origin underlying verbal fluency deficits in schizophrenia. The links between these deficits and information processing speed as well as working memory are well established. These two cognitive domains also appear to be strong predictors of performance in semantic and orthographic fluency tasks in schizophrenia. Individuals with schizophrenia usually present with a significant slowdown in the speed of information processing. Such a slowdown is likely to account for their poor performance in verbal fluency tests, which require the independent and rapid production of words. Working memory disorders are also core cognitive symptoms of schizophrenia. Working memory is involved in verbal fluency tests since they involve “strategic” activation of verbal information in long-term memory, inhibition of inappropriate words, switching between clusters, etc. However, the concept of working memory also partially encompasses the notion of executive functions so that the results reported in the present literature review, according to which impairment of verbal fluency in schizophrenia results from working memory deficits but not from executive functions deficits, are difficult to interpret. Results are also less clear-cut in regard to verbal long-term memory and to language abilities. Finally, numerous studies had shown that individuals with schizophrenia present specific deficits in the organization of semantic memory. However, the impact of this deficit on verbal fluency was explored in one study only. To conclude, verbal fluency tests are sensitive to various neurocognitive conditions and are helpful for differential diagnosis. Further studies are still needed to clarify the functional origin of verbal fluency deficits in schizophrenia, in particular the differential role of executive functions and working memory as well as the impact of semantic memory impairment.

Analysis of the non-stationarity of neural activity during an auditory oddball task in schizophrenia.

The aim of this study was to characterize brain dynamics during an auditory oddball task. For this purpose, a measure of the non-stationarity of a given time-frequency representation (TFR) was applied to electroencephalographic (EEG) signals. EEG activity was acquired from 20 schizophrenic (SCH) patients and 20 healthy controls while they underwent a three-stimulus auditory oddball task. The Degree of Stationarity (DS), a measure of the non-stationarity of the TFR, was computed using the continuous wavelet transform. DS was calculated for both the baseline [-300 0] ms and active task [150 550] ms windows of a P300 auditory oddball task. Results showed a statistically significant increase (p<;0.05) in non-stationarity for controls during the cognitive task in the central region, while less widespread statistically significant differences were obtained for SCH patients, especially in the beta-2 and gamma bands. Our findings support the relevance of DS as a means to study cerebral processing in SCH. Furthermore, the lack of statistically significant changes in DS for SCH patients suggests an abnormal reorganization of neural dynamics during an oddball task.

PM477. Social functioning and prefrontal hemodynamic responses during a verbal fluency task in schizophrenia

PM477. Social functioning and prefrontal hemodynamic responses during a verbal fluency task in schizophrenia

Nicotine restores functional connectivity of the ventral attention network in schizophrenia

While previous work has suggested that nicotine may transiently improve attention deficits in schizophrenia, the neuronal mechanisms are poorly understood. This study is the first to examine the effects of nicotine on connectivity within the ventral attention network (VAN) during a selective attention task in schizophrenia. Using a crossover design, 17 nonsmoking patients with schizophrenia and 20 age/gender-matched nonsmoking healthy controls performed a go/no-go task with environmental noise distractors during application of a 7 mg nicotine or placebo patch. Psychophysiological interaction analysis was performed to analyze task-associated changes in connectivity between a ventral parietal cortex (VPC) seed and the inferior frontal gyrus (IFG), key components of the human VAN. Effects of nicotine on resting state VAN connectivity were also examined. A significant diagnosis × drug interaction was observed on task-associated connectivity between the VPC seed and the left IFG (F(1,35) = 8.03, p < 0.01). This effect was driven by decreased connectivity after placebo in patients and greater connectivity after nicotine. Resting state connectivity analysis showed a significant main effect of diagnosis between the seed and right IFG (F = 4.25, p = 0.023) due to increased connectivity in patients during placebo, but no drug × diagnosis interactions or main effects of drug. This study is the first to demonstrate that 1) the VAN is disconnected in schizophrenia during selective attention, and 2) nicotine may normalize this pathological state.

Social cognition and prefrontal hemodynamic responses during a working memory task in schizophrenia.

Social cognition is an important determinant of functional impairment in schizophrenia, but its relationship with the prefrontal functional abnormalities associated with the condition is still unclear. The present study aimed to explore the relationship between social cognition and prefrontal function in patients with schizophrenia using 52-channel near-infrared spectroscopy (NIRS). Twenty-six patients with schizophrenia and 26 age-, gender-, and intelligence quotient-matched healthy controls (HCs) participated in the study. Hemodynamic responses in the prefrontal and superior temporal cortical regions were assessed during a working memory task using NIRS. Social cognition was assessed using the Social Cognition Screening Questionnaire (SCSQ). The observed hemodynamic responses were significantly reduced in the lateral prefrontal cortex (PFC), the frontopolar cortex, and temporal regions in subjects with schizophrenia compared to HCs. Additionally, lateral PFC hemodynamic responses assessed during the working memory task demonstrated a strong positive correlation with the SCSQ theory of mind (ToM) subscale score even after controlling for working memory performance. These results suggest that ToM integrity is closely related to lateral PFC functional abnormalities found in patients with schizophrenia. In addition, this study provides evidence to suggest that NIRS could be used to identify biomarkers of social cognition function in subjects with schizophrenia.

ID 522 – Neural substrates of cognitive and affective perspective-taking in schizophrenia: A meta-analysis

Introduction Schizophrenia is a neurodevelopmental disorder and patients suffering from this disorder have difficulties in daily functioning and social interactions. These difficulties are better explained by deficit in social cognition than by general neurocognitive deficit. Method We meta-analyzed neuroimaging studies involving perspective-taking tasks in schizophrenia using seed-based d Mapping. The perspective taking of affective and cognitive mental states were considered separately. Results Processing of cognitive mental states in people with schizophrenia, compared to healthy controls, were associated with hyperactivation in left temporo-parietal junction, left temporal lobe, and bilateral prefrontal areas and hypoactivation in medial prefrontal cortex, anterior cingulate, right temporal lobes, insula and left cuneus. Similarly, processing of affective mental states were associated with hyperactivation in primary somatosensory cortex, prefrontal cortex and left cuneus, and hypoactivation in ventrolateral prefrontal cortex and anterior cingulate. In addition, the abnormal brain activation in schizophrenia was present also when no deficit in behavioral performance was found. Summary People with schizophrenia showed abnormal activation in areas associated with perspective-taking. The findings supports the idea the deficit in social cognition in schizophrenia has biological nature and that it is connected to both affective and cognitive aspects of perspective-taking.

Inefficient DMN Suppression in Schizophrenia Patients with Impaired Cognitive Function but not Patients with Preserved Cognitive Function.

Previous studies have observed reduced suppression of the default mode network (DMN) during cognitive tasks in schizophrenia, suggesting inefficient DMN suppression is critical for the cognitive deficits of schizophrenia. Cognitive function in schizophrenia patients, however, varies from relatively intact to severely impaired. This study, which compared the DMN suppression patterns between first-episode schizophrenia patients with (SZ-Imp) and without (SZ-Pre) impaired cognitive function, may provide further insight into the role of DMN dysfunction in cognitive deficits of schizophrenia. Independent component analysis (ICA) was applied to resting-state fMRI data to identify the DMN in each subject, and then general linear modeling based on the task-fMRI data was used to examine the different DMN activation patterns between groups. We observed that the SZ-Imp group, but not the SZ-Pre group, showed reduced suppression in the medial prefrontal cortex and posterior cingulated cortex when compared to the healthy controls (HC) group. Moreover, less DMN suppression was associated with poorer task performance in both HC and patient groups. Our findings provide the first direct evidence that disrupted DMN activity only exists in schizophrenia patients with impaired cognitive function, supporting the specific neuro-pathological role of inefficient DMN suppression in cognitive deficits of first-episode schizophrenia.

Self-reported social functioning and prefrontal hemodynamic responses during a cognitive task in schizophrenia

Impaired social functioning is a characteristic of schizophrenia that affects patients’ quality of life. The aim of the study was to assess prefrontal hemodynamic responses during a cognitive task and establish its influence on psychiatric symptoms, cognitive function, global functioning, and self-reported social functioning in patients with schizophrenia. Thirty-three patients with schizophrenia and 30 age-and sex-matched healthy controls participated in the study. We measured hemodynamic responses in the prefrontal and superior temporal cortical surface areas with 52-channel near-infrared spectroscopy (NIRS) during a verbal fluency task (VFT). Self-reported social functioning was assessed using the Social Functioning Scale (SFS). Regional hemodynamic responses were significantly smaller in the prefrontal and temporal regions in subjects with schizophrenia than in the controls, and prefrontal hemodynamic responses during the VFT showed a strong correlation with SFS total scores. These results suggest an association between self-reported social functioning and prefrontal activation in subjects with schizophrenia. The present study provides evidence that NIRS imaging could be helpful in understanding the neural basis of social functioning.

Neural Network Reorganization Analysis During an Auditory Oddball Task in Schizophrenia Using Wavelet Entropy

The aim of the present study was to characterize the neural network reorganization during a cognitive task in schizophrenia (SCH) by means of wavelet entropy (WE). Previous studies suggest that the cognitive impairment in patients with SCH could be related to the disrupted integrative functions of neural circuits. Nevertheless, further characterization of this effect is needed, especially in the time-frequency domain. This characterization is sensitive to fast neuronal dynamics and their synchronization that may be an important component of distributed neuronal interactions; especially in light of the disconnection hypothesis for SCH and its electrophysiological correlates. In this work, the irregularity dynamics elicited by an auditory oddball paradigm were analyzed through synchronized-averaging (SA) and single-trial (ST) analyses. They provide complementary information on the spatial patterns involved in the neural network reorganization. Our results from 20 healthy controls and 20 SCH patients showed a WE decrease from baseline to response both in controls and SCH subjects. These changes were significantly more pronounced for healthy controls after ST analysis, mainly in central and frontopolar areas. On the other hand, SA analysis showed more widespread spatial differences than ST results. These findings suggest that the activation response is weakly phase-locked to stimulus onset in SCH and related to the default mode and salience networks. Furthermore, the less pronounced changes in WE from baseline to response for SCH patients suggest an impaired ability to reorganize neural dynamics during an oddball task.

Effort-Based Decision Making: A Novel Approach for Assessing Motivation in Schizophrenia.

Because negative symptoms, including motivational deficits, are a critical unmet need in schizophrenia, there are many ongoing efforts to develop new pharmacological and psychosocial interventions for these impairments. A common challenge of these studies involves how to evaluate and select optimal endpoints. Currently, all studies of negative symptoms in schizophrenia depend on ratings from clinician-conducted interviews. Effort-based decision-making tasks may provide a more objective, and perhaps more sensitive, endpoint for trials of motivational negative symptoms. These tasks assess how much effort a person is willing to exert for a given level of reward. This area has been well-studied with animal models of effort and motivation, and effort-based decision-making tasks have been adapted for use in humans. Very recently, several studies have examined physical and cognitive types of effort-based decision-making tasks in cross-sectional studies of schizophrenia, providing evidence for effort-related impairment in this illness. This article covers the theoretical background on effort-based decision-making tasks to provide a context for the subsequent articles in this theme section. In addition, we review the existing literature of studies using these tasks in schizophrenia, consider some practical challenges in adapting them for use in clinical trials in schizophrenia, and discuss interpretive challenges that are central to these types of tasks.

Effect of metabotropic glutamate receptor-3 variants on prefrontal brain activity in schizophrenia: An imaging genetics study using multi-channel near-infrared spectroscopy.

The glutamatergic system is essential for learning and memory through its crucial role in neural development and synaptic plasticity. Genes associated with the glutamatergic system, including metabotropic glutamate receptor (mGluR or GRM) genes, have been implicated in the pathophysiology of schizophrenia. Few studies, however, have investigated a relationship between polymorphism of glutamate-related genes and cortical function in vivo in patients with schizophrenia. We thus explored an association between genetic variations in GRM3 and brain activation driven by a cognitive task in the prefrontal cortex in patients with schizophrenia. Thirty-one outpatients with schizophrenia and 48 healthy controls participated in this study. We measured four candidate single nucleotide polymorphisms (rs274622, rs2299225, rs1468412, and rs6465084) of GRM3, and activity in the prefrontal and temporal cortices during a category version of a verbal fluency task, using a 52-channel near-infrared spectroscopy instrument. The rs274622 C carriers with schizophrenia were associated with significantly smaller prefrontal activation than patients with TT genotype. This between-genotype difference tended to be confined to the patient group. GRM3 polymorphisms are associated with prefrontal activation during cognitive task in schizophrenia.

Dissociation of explicit and implicit responses during a change blindness task in schizophrenia

BackgroundPatients with schizophrenia are abnormally disturbed by information onsets, which may result in a disadvantage in filtering relevant information. The paradigm of change blindness offers the interesting possibility of studying sensitivity to the sudden irruption of visual information with ecological stimuli in schizophrenia. An increased attentional capture by the irruption of visual information would suggest better performance in patients than in healthy controls. This approach has the advantage of circumventing a non-specific general attentional deficit in schizophrenia. MethodsSixteen patients with schizophrenia and 16 healthy controls were asked to detect changes in 99 scenes with 0, 1 or 3 changes. We measured the participants' speed and accuracy in explicitly reporting the changes via motor responses and their capacity to implicitly detect changes via eye movements. ResultsAlthough the controls were faster and more efficient in explicitly reporting changes, the patients' eyes shifted more quickly toward the changes. Regardless of the group, increasing the magnitude of change improved the performance. ConclusionsThe better capacity of the patients to shift their eyes toward changes confirmed the capture by the sudden irruption of visual information in schizophrenia while avoiding the effects of general attentional deficits. However, the striking dissociation between this implicit response and the capacity to explicitly report changes could be interpreted as a deficit in access to conscious perception.

Response inhibition and response monitoring in a saccadic double-step task in schizophrenia

Background: Cognitive control impairments are linked to functional outcome in schizophrenia. The goal of the current study was to investigate precise abnormalities in two aspects of cognitive control: reactively changing a prepared response, and monitoring performance and adjusting behavior accordingly. We adapted an oculomotor task from neurophysiological studies of the cellular basis of cognitive control in nonhuman primates. Methods: 16 medicated outpatients with schizophrenia (SZ) and 18 demographically-matched healthy controls performed the modified double-step task. In this task, participants were required to make a saccade to a visual target. Infrequently, the target jumped to a new location and participants were instructed to rapidly inhibit and change their response. A race model provided an estimate of the time needed to cancel a planned movement. Response monitoring was assessed by measuring reaction time (RT) adjustments based on trial history. Results: SZ patients had normal visually-guided saccadic RTs but required more time to switch the response to the new target location. Additionally, the estimated latency of inhibition was longer in patients and related to employment. Finally, although both groups slowed down on trials that required inhibiting and changing a response, patients showed exaggerated performance-based adjustments in RTs, which was correlated with positive symptom severity. Conclusions: SZ patients have impairments in rapidly inhibiting eye movements and show idiosyncratic response monitoring. These results are consistent with functional abnormalities in a network involving cortical oculomotor regions, the superior colliculus, and basal ganglia, as described in neurophysiological studies of non-human primates using an identical paradigm, and provide a translational bridge for understanding cognitive symptoms of SZ.