Atypical scanpaths in schizophrenia: evidence of a trait- or state-dependent phenomenon?

Tablet-Based Cognitive and Eye Movement Measures as Accessible Tools for Schizophrenia Assessment: Multisite Usability Study

BACKGROUND

Schizophrenia is a complex mental disorder characterized by significant cognitive and neurobiological alterations. Impairments in cognitive function and eye movement have been known to be promising biomarkers for schizophrenia. However, cognitive assessment methods require specialized expertise. To date, data on simplified measurement tools for assessing both cognitive function and eye movement in patients with schizophrenia are lacking.

OBJECTIVE

This study aims to assess the efficacy of a novel tablet-based platform combining cognitive and eye movement measures for classifying schizophrenia.

METHODS

Forty-four patients with schizophrenia, 67 healthy controls, and 41 patients with other psychiatric diagnoses participated in this study from 10 sites across Japan. A free-viewing eye movement task and 2 cognitive assessment tools (Codebreaker task from the THINC-integrated tool and the CognitiveFunctionTest app) were used for conducting assessments in a 12.9-inch iPad Pro. We performed comparative group and logistic regression analyses for evaluating the diagnostic efficacy of the 3 measures of interest.

RESULTS

Cognitive and eye movement measures differed significantly between patients with schizophrenia and healthy controls (all 3 measures; P<.001). The Codebreaker task showed the highest classification effectiveness in distinguishing schizophrenia with an area under the receiver operating characteristic curve of 0.90. Combining cognitive and eye movement measures further improved accuracy with a maximum area under the receiver operating characteristic curve of 0.94. Cognitive measures were more effective in differentiating patients with schizophrenia from healthy controls, whereas eye movement measures better differentiated schizophrenia from other psychiatric conditions.

CONCLUSIONS

This multisite study demonstrates the feasibility and effectiveness of a tablet-based app for assessing cognitive functioning and eye movements in patients with schizophrenia. Our results suggest the potential of tablet-based assessments of cognitive function and eye movement as simple and accessible evaluation tools, which may be useful for future clinical implementation.

Visual salience is affected in participants with schizophrenia during free-viewing

Abnormalities in visual exploration affect the daily lives of patients with schizophrenia. For example, scanpath length during free-viewing is shorter in schizophrenia. However, its origin and its relevance to symptoms are unknown. Here we investigate the possibility that abnormalities in eye movements result from abnormalities in visual or visuo-cognitive processing. More specifically, we examined whether such abnormalities reflect visual salience in schizophrenia. Eye movements of 82 patients and 252 healthy individuals viewing natural and/or complex images were examined using saliency maps for static images to determine the contributions of low-level visual features to salience-guided eye movements. The results showed that the mean value for orientation salience at the gazes of the participants with schizophrenia were higher than that of the healthy control subjects. Further analyses revealed that orientation salience defined by the L + M channel of the DKL color space is specifically affected in schizophrenia, suggesting abnormalities in the magnocellular visual pathway. By looking into the computational stages of the visual salience, we found that the difference between schizophrenia and healthy control emerges at the earlier stage, suggesting functional decline in early visual processing. These results suggest that visual salience is affected in schizophrenia, thereby expanding the concept of the aberrant salience hypothesis of psychosis to the visual domain.

The Gaze of Schizophrenia Patients Captured by Bottom-up Saliency

Schizophrenia (SCHZ) notably impacts various human perceptual modalities, including vision. Prior research has identified marked abnormalities in perceptual organization in SCHZ, predominantly attributed to deficits in bottom-up processing. Our study introduces a novel paradigm to differentiate the roles of top-down and bottom-up processes in visual perception in SCHZ. We analysed eye-tracking fixation ground truth maps from 28 SCHZ patients and 25 healthy controls (HC), comparing these with two mathematical models of visual saliency: one bottom-up, based on the physical attributes of images, and the other top-down, incorporating machine learning. While the bottom-up (GBVS) model revealed no significant overall differences between groups (beta = 0.01, p = 0.281, with a marginal increase in SCHZ patients), it did show enhanced performance by SCHZ patients with highly salient images. Conversely, the top-down (EML-Net) model indicated no general group difference (beta = -0.03, p = 0.206, lower in SCHZ patients) but highlighted significantly reduced performance in SCHZ patients for images depicting social interactions (beta = -0.06, p < 0.001). Over time, the disparity between the groups diminished for both models. The previously reported bottom-up bias in SCHZ patients was apparent only during the initial stages of visual exploration and corresponded with progressively shorter fixation durations in this group. Our research proposes an innovative approach to understanding early visual information processing in SCHZ patients, shedding light on the interplay between bottom-up perception and top-down cognition.

Visual processing of complex social scenes in 22q11.2 deletion syndrome: Relevance for negative symptoms

Current explanatory models of negative symptoms in schizophrenia have suggested the role of social cognition in symptom formation and maintenance. This study examined a core aspect of social cognition, namely social perception, and its association with clinical manifestations in 22q11.2 deletion syndrome (22q11DS), a genetic model of schizophrenia. We used an eye-tracking device to analyze developmental trajectories of complex and dynamic social scenes exploration in 58 participants with 22q11DS compared to 79 typically developing controls. Participants with 22q11DS showed divergent patterns of social scene exploration compared to healthy individuals from childhood to adulthood. We evidenced a more scattered gaze pattern and a lower number of shared gaze foci compared to healthy controls. Associations with negative symptoms, anxiety level, and face recognition were observed. Findings reveal abnormal visual exploration of complex social information from childhood to adulthood in 22q11DS. Atypical gaze patterns appear related to clinical manifestations in this syndrome.

Perceptual Functioning

Perceptual disorders are not part of the diagnosis criteria for schizophrenia. Yet, a considerable amount of work has been conducted, especially on visual perception abnormalities, and there is little doubt that visual perception is altered in patients. There are several reasons why such perturbations are of interest in this pathology. They are observed during the prodromal phase of psychosis, they are related to the pathophysiology (clinical disorganization, disorders of the sense of self), and they are associated with neuronal connectivity disorders. Perturbations occur at different levels of processing and likely affect how patients interact and adapt to their surroundings. The literature has become very large, and here we try to summarize different models that have guided the exploration of perception in patients. We also illustrate several lines of research by showing how perception has been investigated and by discussing the interpretation of the results. In addition to discussing domains such as contrast sensitivity, masking, and visual grouping, we develop more recent fields like processing at the level of the retina, and the timing of perception.

Eye-movement analysis on facial expression for identifying children and adults with neurodevelopmental disorders

Experienced psychiatrists identify people with autism spectrum disorder (ASD) and schizophrenia (Sz) through interviews based on diagnostic criteria, their responses, and various neuropsychological tests. To improve the clinical diagnosis of neurodevelopmental disorders such as ASD and Sz, the discovery of disorder-specific biomarkers and behavioral indicators with sufficient sensitivity is important. In recent years, studies have been conducted using machine learning to make more accurate predictions. Among various indicators, eye movement, which can be easily obtained, has attracted much attention and various studies have been conducted for ASD and Sz. Eye movement specificity during facial expression recognition has been studied extensively in the past, but modeling taking into account differences in specificity among facial expressions has not been conducted. In this paper, we propose a method to detect ASD or Sz from eye movement during the Facial Emotion Identification Test (FEIT) while considering differences in eye movement due to the facial expressions presented. We also confirm that weighting using the differences improves classification accuracy. Our data set sample consisted of 15 adults with ASD and Sz, 16 controls, and 15 children with ASD and 17 controls. Random forest was used to weight each test and classify the participants as control, ASD, or Sz. The most successful approach used heat maps and convolutional neural networks (CNN) for eye retention. This method classified Sz in adults with 64.5% accuracy, ASD in adults with up to 71.0% accuracy, and ASD in children with 66.7% accuracy. Classifying of ASD result was significantly different (p<.05) by the binomial test with chance rate. The results show a 10% and 16.7% improvement in accuracy, respectively, compared to a model that does not take facial expressions into account. In ASD, this indicates that modeling is effective, which weights the output of each image.

Inefficient integration during multiple facial processing in pre-morbid and early phases of psychosis

OBJECTIVES

We used eye-tracking to evaluate multiple facial context processing and event-related potential (ERP) to evaluate multiple facial recognition in individuals at clinical high risk (CHR) for psychosis.

METHODS

In total, 173 subjects (83 CHRs and 90 healthy controls [HCs]) were included and their emotion perception performances were accessed. A total of 40 CHRs and 40 well-matched HCs completed an eye-tracking task where they viewed pictures depicting a person in the foreground, presented as context-free, context-compatible, and context-incompatible. During the two-year follow-up, 26 CHRs developed psychosis, including 17 individuals who developed first-episode schizophrenia (FES). Eighteen well-matched HCs were made to complete the face number detection ERP task with image stimuli of one, two, or three faces.

RESULTS

Compared to the HC group, the CHR group showed reduced visual attention to contextual processing when viewing multiple faces. With the increasing complexity of contextual faces, the differences in eye-tracking characteristics also increased. In the ERP task, the N170 amplitude decreased with a higher face number in FES patients, while it increased with a higher face number in HCs.

CONCLUSIONS

Individuals in the very early phase of psychosis showed facial processing deficits with supporting evidence of different scan paths during context processing and disruption of N170 during multiple facial recognition.

Evaluation of the correlation between gaze avoidance and schizophrenia psychopathology with deep learning-based emotional recognition

OBJECTIVE

To investigate the correlation between gaze avoidance and psychopathology in patients with schizophrenia through eye movement measurements in real-life interpersonal situations.

METHODS

We enrolled 52 clinically stable patients with schizophrenia. Psychopathology was evaluated using the Positive and Negative Syndrome Scale (PANSS), Hamilton Depression Rating Scale, and Hamilton Anxiety Rating Scale. After presenting a visual stimulus, eye movements were measured with Tobii Pro Wearable Glasses 2, and deep learning-based emotional recognition using the residual masking network was used for neutral stimulus verification. Statistical analyses were performed using Pearson's correlation and regression analyses.

RESULTS

Data of 45 participants with verified stimulus neutrality by deep learning image recognition were used for analysis. The first dwelling time was negatively correlated with the PANSS positive syndrome subscale (p = 0.028), general psychopathology subscale (p = 0.008), total score (p = 0.008), 5-factor positive symptoms (p = 0.035), and 5-factor depression/anxiety symptoms (p = 0.043). The baseline-area of interest (AOI) pupil diameter change was positively correlated with PANSS 5-factor positive symptom scores (p = 0.039). After adjusting for additional variables, the same items had a significant effect on the first dwelling time and baseline-AOI pupil diameter change.

CONCLUSIONS

Psychopathology, particularly positive symptoms, was associated with gaze avoidance and pupil diameter in patients with schizophrenia. Evaluating the characteristics of eye movements in patients with schizophrenia will enable better understanding of their symptoms.

Contribution of Eye-Tracking to Study Cognitive Impairments Among Clinical Populations

In the field of psychology, the merge of decision-theory and neuroscientific methods produces an array of scientifically recognized paradigms. For example, by exploring consumer’s eye-movement behavior, researchers aim to deepen the understanding of how patterns of retinal activation are being meaningfully transformed into visual experiences and connected with specific reactions (e.g., purchase). Notably, eye-movements provide knowledge of one’s homeostatic balance and gatekeep information that shape decisions. Hence, vision science investigates the quality of observed environments determined under various experimental conditions. Moreover, it answers questions on how human process visual stimuli and use gained information for a successful strategy to achieve certain goals. While capturing cognitive states with the support of the eye-trackers progresses at a relatively fast pace in decision-making research, measuring the visual performance of real-life tasks, which require complex cognitive skills, is tentatively translated into clinical experiments. Nevertheless, the potential of the human eye as a highly valuable source of biomarkers has been underlined. In this article, we aim to draw readers attention to decision-making experimental paradigms supported with eye-tracking technology among clinical populations. Such interdisciplinary approach may become an important component that will (i) help in objectively illustrating patient’s models of beliefs and values, (ii) support clinical interventions, and (iii) contribute to health services. It is possible that shortly, eye-movement data from decision-making experiments will grant the scientific community a greater understanding of mechanisms underlining mental states and consumption practices that medical professionals consider as obsessions, disorders or addiction.

The limited effect of neural stimulation on visual attention and social cognition in individuals with schizophrenia

BACKGROUND

Research demonstrates a relationship between faulty visual attention and poorer social cognition in schizophrenia. One potential explanatory model suggests abnormal neuromodulation in specific neural networks may result in reduced attention to socially important cues, leading to poorer understanding of another's emotional state or intentions.

OBJECTIVE

The current study experimentally manipulated neural networks using tDCS to examine this potential causal mechanism. The primary aim was to determine whether stimulation to the right temporoparietal junction (rTPJ) improves visual attention, and secondary aims were to determine whether 1) stimulation improves social cognitive performance and 2) visual attention moderates this improved performance.

METHOD

Using a double-blind crossover design, 69 individuals with schizophrenia underwent both active and sham stimulation to either the rTPJ of the ventral attention network (n = 36) or the dorsomedial prefrontal cortex of the social brain network (dmPFC; n = 33). Following stimulation, participants completed tasks assessing emotion recognition and mentalizing. Concurrent eye tracking assessed visual attention, measuring proportion of time spent attending to areas of interest.

RESULTS

For emotion recognition, stimulation failed to impact either visual attention or social cognitive task accuracy. Similarly, neurostimulation failed to affect visual attention on the mentalizing task. However, exploratory analyses demonstrated that mentalizing accuracy significantly improved after stimulation to the active comparator, dmPFC, with no improvement after stimulation to rTPJ.

CONCLUSION

Results demonstrate limited effect of a single stimulation session on visual attention and emotion recognition accuracy but provide initial support for an alternate neural mechanism for mentalizing, highlighting the importance of executive functions over visual attention.

Recent updates of eye movement abnormalities in patients with schizophrenia: A scoping review

AIM

Although eye-tracking technology expands beyond capturing eye data just for the sole purpose of ensuring participants maintain their gaze at the presented fixation cross, gaze technology remains of less importance in clinical research. Recently, impairments in visual information encoding processes indexed by novel gaze metrics have been frequently reported in patients with schizophrenia. This work undertakes a scoping review of research on saccadic dysfunctions and exploratory eye movement deficits among patients with schizophrenia. It gathers promising pieces of evidence of eye movement abnormalities in attention-demanding tasks on the schizophrenia spectrum that have mounted in recent years and their outcomes as potential biological markers.

METHODS

The protocol was drafted based on PRISMA for scoping review guidelines. Electronic databases were systematically searched to identify articles published between 2010 and 2020 that examined visual processing in patients with schizophrenia and reported eye movement characteristics as potential biomarkers for this mental illness.

RESULTS

The use of modern eye-tracking instrumentation has been reported by numerous neuroscientific studies to successfully and non-invasively improve the detection of visual information processing impairments among the screened population at risk of and identified with schizophrenia.

CONCLUSIONS

Eye-tracking technology has the potential to contribute to the process of early intervention and more apparent separation of the diagnostic entities, being put together by the syndrome-based approach to the diagnosis of schizophrenia. However, context-processing paradigms should be conducted and reported in equally accessible publications to build comprehensive models.

Effects of age and sex on eye movement characteristics

Abnormal eye movements are often associated with psychiatric disorders. Eye movements are sensorimotor functions of the brain, and aging and sex would affect their characteristics. A precise understanding of normal eye movements is required to distinguish disease-related abnormalities from natural differences associated with aging or sex. To date, there is no multicohort study examining age-related dependency and sex effects of eye movements in healthy, normal individuals using large samples to ensure the robustness and reproducibility of the results. In this study, we aimed to provide findings showing the impact of age and sex on eye movement measures. The present study used eye movement measures of more than seven hundred healthy individuals from three large independent cohorts. We herein evaluated eye movement measures quantified by using a set of standard eye movement tests that have been utilized for the examination of patients with schizophrenia. We assessed the statistical significance of the effects of age and sex and its reproducibility across cohorts. We found that 4-18 out of 35 eye movement measures were significantly correlated with age, depending on the cohort, and that 10 of those, which are related to the fixation and motor control of smooth pursuit and saccades, showed high reproducibility. On the other hand, the effects of sex, if any, were less reproducible. The present results suggest that we should take age into account when we evaluate abnormalities in eye movements.

Impaired inhibition of return during free-viewing behaviour in patients with schizophrenia

Schizophrenia affects various aspects of cognitive and behavioural functioning. Eye movement abnormalities are commonly observed in patients with schizophrenia (SZs). Here we examined whether such abnormalities reflect an anomaly in inhibition of return (IOR), the mechanism that inhibits orienting to previously fixated or attended locations. We analyzed spatiotemporal patterns of eye movement during free-viewing of visual images including natural scenes, geometrical patterns, and pseudorandom noise in SZs and healthy control participants (HCs). SZs made saccades to previously fixated locations more frequently than HCs. The time lapse from the preceding saccade was longer for return saccades than for forward saccades in both SZs and HCs, but the difference was smaller in SZs. SZs explored a smaller area than HCs. Generalized linear mixed-effect model analysis indicated that the frequent return saccades served to confine SZs' visual exploration to localized regions. The higher probability of return saccades in SZs was related to cognitive decline after disease onset but not to the dose of prescribed antipsychotics. We conclude that SZs exhibited attenuated IOR under free-viewing conditions, which led to restricted scene scanning. IOR attenuation will be a useful clue for detecting impairment in attention/orienting control and accompanying cognitive decline in schizophrenia.

Minds and Brains, Sleep and Psychiatry

Objective

This article offers a philosophical thesis for psychiatric disorders that rests upon some simple truths about the mind and brain. Specifically, it asks whether the dual aspect monism—that emerges from sleep research and theoretical neurobiology—can be applied to pathophysiology and psychopathology in psychiatry.

Methods

Our starting point is that the mind and brain are emergent aspects of the same (neuronal) dynamics; namely, the brain–mind. Our endpoint is that synaptic dysconnection syndromes inherit the same dual aspect; namely, aberrant inference or belief updating on the one hand, and a failure of neuromodulatory synaptic gain control on the other. We start with some basic considerations from sleep research that integrate the phenomenology of dreaming with the neurophysiology of sleep.

Results

We then leverage this treatment by treating the brain as an organ of inference. Our particular focus is on the role of precision (i.e., the representation of uncertainty) in belief updating and the accompanying synaptic mechanisms.

Conclusions

Finally, we suggest a dual aspect approach—based upon belief updating (i.e., mind processes) and its neurophysiological implementation (i.e., brain processes)—has a wide explanatory compass for psychiatry and various movement disorders. This approach identifies the kind of pathophysiology that underwrites psychopathology—and points to certain psychotherapeutic and psychopharmacological targets, which may stand in mechanistic relation to each other.

The ‘mind’ emerges from Bayesian belief updating in the ‘brain’

Psychopathology can be read as aberrant belief updating.

Aberrant belief updating follows from any neuromodulatory synaptopathy

An Analysis of Eye-Tracking Features and Modelling Methods for Free-Viewed Standard Stimulus: Application for Schizophrenia Detection

Currently psychiatry is a medical field lacking an automated diagnostic process. The presence of a mental disorder is established by observing its typical symptoms. Eye-movement specifics have already been established as an "endophenotype" for schizophrenia, but an automated diagnostic process of eye-movement analysis is still lacking. This article presents several novel approaches for the automatic detection of a schizophrenic disorder based on a free-view image test using a Rorschach inkblot and an eye tracker. Several features that enabled us to analyse the eye-tracker signal as a whole as well as its specific parts were tested. The variety of features spans global (heat maps, gaze plots), sequences of features (means, variances, and spectra), static (x and y signals as 2D images), dynamic (velocities), and model-based (limiting probabilities and transition matrices) categories. For each set of features, a proper modelling and classification method was designed (convolutional, recurrent, fully connected and combined neural networks; Hidden Markov models). By doing so, it was possible to find the importance of each feature and its physical representation using k-fold cross validation and a paired t-test. The dataset was sampled on 22 people with schizophrenia and 22 healthy individuals. The most successful approach was based on heat maps using all data and convolutional networks, reaching a 78.8% accuracy, which is a 10.5% improvement over the reference method. From all tested methods, there are two in an 85% accuracy range and over fifteen others in a 75% accuracy range at a 10% significance level.

Aberrant Salience, Information Processing, and Dopaminergic Signaling in People at Clinical High Risk for Psychosis

The aberrant salience hypothesis proposes that striatal dopamine dysregulation causes misattribution of salience to irrelevant stimuli leading to psychosis. Recently, new lines of preclinical evidence on information coding by subcortical dopamine coupled with computational models of the brain's ability to predict and make inferences about the world (predictive processing) provide a new perspective on this hypothesis. We review these and summarize the evidence for dopamine dysfunction, reward processing, and salience abnormalities in people at clinical high risk of psychosis (CHR) relative to findings in patients with psychosis. This review identifies consistent evidence for dysregulated subcortical dopamine function in people at CHR, but also indicates a number of areas where neurobiological processes are different in CHR subjects relative to patients with psychosis, particularly in reward processing. We then consider how predictive processing models may explain psychotic symptoms in terms of alterations in prediction error and precision signaling using Bayesian approaches. We also review the potential role of environmental risk factors, particularly early adverse life experiences, in influencing the prior expectations that individuals have about their world in terms of computational models of the progression from being at CHR to frank psychosis. We identify a number of key outstanding questions, including the relative roles of prediction error or precision signaling in the development of symptoms and the mechanism underlying dopamine dysfunction. Finally, we discuss how the integration of computational psychiatry with biological investigation may inform the treatment for people at CHR of psychosis.

Visual Exploration at Higher Fixation Frequency Increases Subsequent Memory Recall

Only a small proportion of what we see can later be recalled. Up to date it is unknown how far differences in visual exploration during encoding affect the strength of episodic memories. Here, we identified individual gaze characteristics by analyzing eye tracking data in a picture encoding task performed by 967 healthy subjects during fMRI. We found a positive correlation between fixation frequency during visual exploration and subsequent free recall performance. Brain imaging results showed a positive correlation of fixation frequency with activations in regions related to vision and memory, including the medial temporal lobe. To investigate if higher fixation frequency is causally linked to better memory, we experimentally manipulated visual exploration patterns in an independent population of 64 subjects. Doubling the number of fixations within a given exploration time increased subsequent free recall performance by 19%. Our findings provide evidence for a causal relationship between fixation frequency and episodic memory for visual information.

The attenuated visual scanpaths of patients with schizophrenia whilst recognizing emotional facial expressions are worsened in natural social scenes

Alteration of visual scanpaths under emotional facial expression in schizophrenia patients has been described in recent years; however, it is not clear whether such results are different when they transfer to faces in natural social scenes. The present study was designed to investigate the effects of emotional faces in natural social scenes on the gaze patterns of patients with schizophrenia, compared to gaze at isolated faces. A novel theme identification task was used where participants selected a positive, neutral or negative word to describe an emotional picture. Participants were 29 patients with schizophrenia and 31 healthy controls. The Positive and Negative Syndrome Scale (PANSS) and the Scale of Social Function in Psychosis Inpatients (SSPI) were used to assess symptoms and social functioning. In total, patients with schizophrenia showed significantly fewer fixations, saccades numbers and decreased fixations in areas of interest. As expected, patients showed shorter scanpath length, but only in the pictures with social settings. Furthermore, the effect size of scanpaths parameters under social scene was all greater than isolated face. In addition, patients compared to controls showed more abnormal scanpath parameters processing negative and neutral faces than positive faces, especially in social scene. The present study suggests that scanpath length for social scene faces may be more sensitive than for isolated face pictures. Our findings further support restricted scanpath whilst recognizing emotional facial expressions in natural social scenes as a favorable topic for further investigation as a trait marker.

An Investigation of the Free Energy Principle for Emotion Recognition

This paper offers a prospectus of what might be achievable in the development of emotional recognition devices. It provides a conceptual overview of the free energy principle; including Markov blankets, active inference, and-in particular-a discussion of selfhood and theory of mind, followed by a brief explanation of how these concepts can explain both neural and cultural models of emotional inference. The underlying hypothesis is that emotion recognition and inference devices will evolve from state-of-the-art deep learning models into active inference schemes that go beyond marketing applications and become adjunct to psychiatric practice. Specifically, this paper proposes that a second wave of emotion recognition devices will be equipped with an emotional lexicon (or the ability to epistemically search for one), allowing the device to resolve uncertainty about emotional states by actively eliciting responses from the user and learning from these responses. Following this, a third wave of emotional devices will converge upon the user's generative model, resulting in the machine and human engaging in a reciprocal, prosocial emotional interaction, i.e., sharing a generative model of emotional states.

Free viewing exploration in schizophrenia: Review of evidence from laboratory settings to natural environment

Several studies have investigated visual processing impairment in schizophrenia. The literature on visual exploration has described restricted scanning in schizophrenia patients. This gaze behavior is characterized by increased fixation duration, a reduced scan path length and avoidance of salient features of the face with emotional content. The aim of this paper is to give an insight on the latest update on scan path deficit. Abnormal gaze exploration was replicated in various visual stimuli. This review describes gaze patterns with stimuli that imply minimal to high cognitive process: figures, objects, faces, and scenes. Interestingly, schizophrenia patients have shown cognitive flexibility by modulating gaze scanning when they are involved in an active assignment. We will also consider scanning abnormalities in real-life environment and discuss the potential therapeutic use of eye tracking in schizophrenia. The therapeutic application of eye tracking in schizophrenia is a young emerging field in psychiatry research. The recent remediation program is based on the reorientation of visual attention on the salient features of faces. For now, this program has shown encouraging results. Further studies are needed to explore behavior in real-world situations to complement laboratory measurements to move toward a full understanding of the mechanisms underlying atypical scanning in patients with schizophrenia.

Comparison of eye movements in schizophrenia and autism spectrum disorder

Aim

Eye movement abnormalities are often associated with psychiatric illness. Subjects with either schizophrenia or autism spectrum disorder (ASD) have been reported to show eye movement abnormalities. However, it is still unclear whether eye movement abnormalities in schizophrenia and in ASD have common features. This study aimed to understand the similarities/differences in eye movement abnormalities of subjects with schizophrenia and those with ASD.

Methods

We analyzed 75 eye movement characteristics of 83 subjects with schizophrenia, 17 subjects with ASD and 255 healthy controls that were collected during fixation, smooth pursuit and free viewing tasks using analysis of covariance with the covariates age and sex.

Results

We found significant effects across groups on 21 eye movement characteristics, of which 4 characteristics had large effect sizes. Post hoc multiple comparisons indicated significant differences between the subjects with schizophrenia and healthy controls across all 21 characteristics. On the other hand, no significant difference between the ASD group and healthy control group was found. Instead, the subjects with ASD showed significant differences from the subjects with schizophrenia in 5 eye movement characteristics during the free viewing and smooth pursuit eye movements.

Conclusions

The present results suggest that eye movement abnormalities in the subjects with ASD are different from those with schizophrenia and that the tasks in this study are suitable to detect eye movement abnormality in schizophrenia. Thus, the eye movement examinations used here may distinguish subjects with schizophrenia from those with ASD.

This study aimed to understand the similarities/differences in eye movement abnormalities of subjects with schizophrenia and those with ASD. The subjects with ASD showed significant differences from the subjects with schizophrenia in five characteristics during the free viewing and smooth pursuit eye movements. The results suggest that eye movement abnormalities in the subjects with ASD are different from those with schizophrenia.

Introducing a Bayesian model of selective attention based on active inference

Information gathering comprises actions whose (sensory) consequences resolve uncertainty (i.e., are salient). In other words, actions that solicit salient information cause the greatest shift in beliefs (i.e., information gain) about the causes of our sensations. However, not all information is relevant to the task at hand: this is especially the case in complex, naturalistic scenes. This paper introduces a formal model of selective attention based on active inference and contextual epistemic foraging. We consider a visual search task with a special emphasis on goal-directed and task-relevant exploration. In this scheme, attention modulates the expected fidelity (precision) of the mapping between observations and hidden states in a state-dependent or context-sensitive manner. This ensures task-irrelevant observations have little expected information gain, and so the agent - driven to reduce expected surprise (i.e., uncertainty) - does not actively seek them out. Instead, it selectively samples task-relevant observations, which inform (task-relevant) hidden states. We further show, through simulations, that the atypical exploratory behaviours in conditions such as autism and anxiety may be due to a failure to appropriately modulate sensory precision in a context-specific way.

The Hyperfocusing Hypothesis: A New Account of Cognitive Dysfunction in Schizophrenia

Impairments in basic cognitive processes such as attention and working memory are commonly observed in people with schizophrenia and are predictive of long-term outcome. In this review, we describe a new theory-the hyperfocusing hypothesis-which provides a unified account of many aspects of impaired cognition in schizophrenia. This hypothesis proposes that schizophrenia involves an abnormally narrow but intense focusing of processing resources. This hyperfocusing impairs the ability of people with schizophrenia to distribute attention among multiple locations, decreases the number of representations that can simultaneously be maintained in working memory, and causes attention to be abnormally captured by irrelevant inputs that share features with active representations. Evidence supporting the hyperfocusing hypothesis comes from a variety of laboratory tasks and from both behavioral and electrophysiological measures of processing. In many of these tasks, people with schizophrenia exhibit supranormal effects of task manipulations, which cannot be explained by a generalized cognitive deficit or by nonspecific factors such as reduced motivation or poor task comprehension. In addition, the degree of hyperfocusing in these tasks is often correlated with the degree of impairment in measures of broad cognitive function, which are known to be related to long-term outcome. Thus, the mechanisms underlying hyperfocusing may be a good target for new treatments targeting cognitive deficits in schizophrenia.

Visual exploration of emotional faces in schizophrenia using masks from the Japanese Noh theatre

Studying eye movements during visual exploration is widely used to investigate visual information processing in schizophrenia. Here, we used masks from the Japanese Noh theatre to study visual exploration behavior during an emotional face recognition task and a brightness evaluation control task using the same stimuli. Eye movements were recorded in 25 patients with schizophrenia and 25 age-matched healthy controls while participants explored seven photos of Japanese Noh masks tilted to seven different angles. Additionally, participants were assessed on seven upright binary black and white pictures of these Noh masks (Mooney-like pictures), seven Upside-down pictures (180° upside-down turned Mooneys), and seven Neutral pictures. Participants either had to indicate whether they had recognized a face and its emotional expression, or they had to evaluate the brightness of the picture (total N = 56 trials). We observed a clear effect of inclination angle of Noh masks on emotional ratings (p < 0.001) and visual exploration behavior in both groups. Controls made larger saccades than patients when not being able to recognize a face in upside-down Mooney pictures (p < 0.01). Patients also made smaller saccades when exploring pictures for brightness (p < 0.05). Exploration behavior in patients was related to depressive symptom expression during emotional face recognition but not during brightness evaluation. Our findings suggest that visual exploration behavior in patients with schizophrenia is less flexible than in controls depending on the specific task requirements, specifically when exploring physical aspects of the environment.

Eye movement abnormalities and their association with cognitive impairments in schizophrenia

BACKGROUND

Eye movement abnormalities have been identified in schizophrenia; however, their relevance to cognition is still unknown. In this study, we explored the general relationship between eye movements and cognitive function.

METHODS

The three eye movement measures (scanpath length, horizontal position gain, and duration of fixations) that were previously reported to be useful in distinguishing subjects with schizophrenia from healthy subjects, as well as Wechsler Adult Intelligence Scale-III (WAIS-III) scores, were collected and tested for association in 113 subjects with schizophrenia and 404 healthy subjects.

RESULTS

Scanpath length was positively correlated with matrix reasoning and digit symbol coding in subjects with schizophrenia and correlated with vocabulary and symbol search in healthy subjects. Upon testing for interaction effects of diagnosis and scanpath length on correlated WAIS-III scores, a significant interaction effect was only observed for matrix reasoning. The positive correlation between scanpath length and matrix reasoning, which was specific to subjects with schizophrenia, remained significant after controlling for demographic confounders such as medication and negative symptoms. No correlation was observed between the two other eye movement measures and any of the WAIS-III scores.

CONCLUSIONS

Herein, we reveal novel findings on the association between eye-movement-based measures of visual exploration and cognitive scores requiring visual search in subjects with schizophrenia and in healthy subjects. The association between scanpath length and matrix reasoning, a measure of perceptual organization in subjects with schizophrenia, implies the existence of common cognitive processes, and subjects with longer scanpath length may be advantageous in performance of perceptual organization tasks.

Inflexible eye fixation pattern in schizophrenia affecting decision-making on daily life

Patients with schizophrenia have difficulties in real life due to impairment in ability to make decisions. The purpose of this study was to elucidate the relationship between impaired decision-making processes with real life stimuli and abnormal eye gaze patterns in patients with schizophrenia. Each of 23 patients with schizophrenia and 23 healthy controls performed an apparel purchase decision task including the influencing factors such as preference, fit, and price, during which the eye gaze was traced. Fixation time and fixation time ratio on areas of interest, which were set for participant faces and clothing, were compared between the two groups. Compared with controls, patients made purchase decisions at a higher rate and showed significantly shorter fixation time on clothing in the preference, fit, and price phases and on faces in the purchase phase. Fixation time ratio of face over clothing did not change over purchase decisions in patients, whereas controls showed significantly higher fixation time ratio in not-to-buy decisions than in to-buy decisions. These results suggest that aberrant decision-making behaviors in patients with schizophrenia are closely related to inflexible visual information gathering patterns because they apportion the same amount of attention to objects regardless of purchase intention.

Eye-tracking research in eating disorders: A systematic review

OBJECTIVE

Those with eating disorders (EDs) show attentional biases to disorder-relevant stimuli, such as food and body shape information. However, attentional bias research in EDs largely relies on reaction time based measures, which are limited in their ability to assess different components and the time course of attention. Eye-tracking paradigms have therefore been utilized to provide greater ecological validity, and directly capture the detailed sequence of processes in perception and attention. While numerous studies have examined eye movements in the mood, anxiety, and psychotic disorders, there has been a lack of studies in EDs. The purpose of this qualitative review is to provide a summary of eye-tracking studies in clinical ED populations.

METHOD

The review was conducted using the PRISMA guidelines. Electronic databases were systematically searched to identify studies examining gaze parameters in ED compared to healthy controls (HCs). Thirty-one studies met inclusion criteria.

RESULTS

Across ED diagnoses, there was evidence of attentional biases towards food and body stimuli. In addition, differential patterns of attention to social information, and differences in smooth pursuit and saccadic eye movements were found in anorexia nervosa (AN).

DISCUSSION

Findings are discussed in relation to research in other psychiatric disorders, and recommendations for future studies using eye-tracking in EDs are given. The findings add to the wider literature on attentional biases in EDs, and provide potential avenues for treatment. IJED-18-0331.R1. Investigación de seguimiento ocular en trastornos de la conducta alimentaria: una revisión sistemática.

A review of impaired visual processing and the daily visual world in patients with schizophrenia

Several studies have investigated perceptual processes in patients with schizophrenia. Research confirms that visual impairments are one of the most important features of schizophrenia. Many studies, using behavioral and psychological experiments, confirm that visual impairments can be used to determine illness severity, state, and best treatments. Herein, we review recent research pertaining to visual function in patients with schizophrenia and highlight the relationship between laboratory findings and subjective, real-life reports from patients themselves. The purpose of this review is to 1) describe visual impairments that manifest in patients with schizophrenia, 2) examine the relationship between visual dysfunction, assessed by laboratory tests, and the experiences of patients themselves, and 3) describe real-life experiences related to visual function in this population. In this review, the impairments of motion and color perception, perceptual organization, and scan paths are summarized, along with the relationship between laboratory findings and patients' real-world subjective experiences related to visual function.

[Oculomotor activity as an indicator of disturbances in perception and programming in patients with schizotypal disorder]

AIM

To consider the patterns of stimuli analysis and task execution in conditions of voluntary and involuntary attention in people with schizotypal disorder from the psychopathological and psychological points of view.

MATERIAL AND METHODS

A total of 40 subjects were examined including 16 patients diagnosed with schizotypal disorder, 13 with personality disorders and 11 without psychiatric pathology (controls). In the first part of the study, subjects looked upon various static images without any instructions, followed by a test with antisaccade task in vertical and horizontal directions; the last task duplicated the first, but the subjects were asked to remember the presented images as best as possible.

RESULTS

In the group of patients with schizotypal disorder, an increase in average and maximum fixation variance, its greater variation between images, and a decrease in the scanpath length were found. These differences were associated with the intentional focus of attention and several indicators of the accomplish efficiency of the antisaccade task.

CONCLUSION

The changes in fixative eye movements observed in individuals with schizotypal disorder indicate violations of information selectivity and construction of an image of future action. Assumptions about inadequacy of their perceptual strategy to the simultaneous one and the primacy of the sense-bearing (motivational) violations in the programming of saccadic activity were made.

Objective assessment of exploratory behaviour in schizophrenia using wireless motion capture

Motivation deficits are a prominent feature of schizophrenia and have substantial consequences for functional outcome. The impact of amotivation on exploratory behaviour has not been extensively assessed by entirely objective means. This study evaluated deficits in exploratory behaviour in an open-field setting using wireless motion capture. Twenty-one stable adult outpatients with schizophrenia and twenty matched healthy controls completed the Novelty Exploration Task, in which participants explored a novel environment containing familiar and uncommon objects. Objective motion data were used to index participants' locomotor activity and tendency for visual and tactile object exploration. Clinical assessments of positive and negative symptoms, apathy, cognition, depression, medication side-effects, and community functioning were also administered. Relationships between task performance and clinical measures were evaluated using Spearman correlations, and group differences were evaluated using multivariate analysis of covariance tests. Although locomotor activity and tactile exploration were similar between the schizophrenia and healthy control groups, schizophrenia participants exhibited reduced visual object exploration (F(2,35)=3.40, p=0.045). Further, schizophrenia participants' geometric pattern of locomotion, visual exploration, and tactile exploration were correlated with overall negative symptoms (|ρ|=0.46-0.64, p<=0.039) and apathy (|ρ|=0.49-0.62, p<=0.028), and both visual and tactile exploration were also correlated with community functioning (|ρ|=0.46-0.48, p<=0.043). The Novelty Exploration Task may be a valuable tool to quantify exploratory behaviour beyond what is captured through standard clinical instruments and human observer ratings. Findings from this initial study suggest that locomotor activity and object interaction tendencies are impacted by motivation, and reveal deficits specifically in visual exploration in schizophrenia.

Microsaccade Characteristics in Neurological and Ophthalmic Disease

Microsaccade research has recently reached a critical mass of studies that allows, for the first time, a comprehensive review of how microsaccadic dynamics change in neurological and ophthalmic disease. We discuss the various pathological conditions that affect microsaccades, their impact on microsaccadic and other fixational eye movement dynamics, and the incipient studies that point to microsaccadic features as potential indicators of differential and early diagnoses of multiple clinical conditions, from movement disorders to attention-deficit hyperactivity disorder to amblyopia. We propose that the objective assessment of fixational eye movement parameters may help refine differential diagnostics in neurological disease and assist in the evaluation of ongoing therapy regimes. In addition, determining the effects of ophthalmic disease on fixational eye movement features may help evaluate visual impairment in an objective manner, particularly in young patients or those experiencing communication difficulties.

Reduced Inferior and Orbital Frontal Thickness in Adolescent Bulimia Nervosa Persists Over Two-Year Follow-Up

OBJECTIVE

Cross-sectional data suggest functional and anatomical disturbances in inferior and orbital frontal regions in bulimia nervosa (BN). Using longitudinal data, we investigated whether reduced cortical thickness (CT) in these regions arises early and persists over adolescence in BN, independent of symptom remission, and whether CT reductions are markers of BN symptoms.

METHOD

A total of 33 adolescent females with BN symptoms (BN or other specified feeding or eating disorder) and 28 healthy adolescents participated in this study. Anatomical magnetic resonance imaging and clinical data were acquired at 3 time points within 2-year intervals over adolescence, with 31% average attrition between assessments. Using a region-of-interest approach, we assessed group differences in CT at baseline and over time, and tested whether between- and within-subject variations in CT were associated with the frequency of BN symptoms.

RESULTS

Reduced CT in the right inferior frontal gyrus persisted over adolescence in BN compared to healthy adolescents, even in those who achieved full or partial remission. Within the BN group, between-subject variations in CT in the inferior and orbital frontal regions were inversely associated with specific BN symptoms, suggesting, on average over time, greater CT reductions in individuals with more frequent BN symptoms.

CONCLUSION

Reduced CT in inferior frontal regions may contribute to illness persistence into adulthood. Reductions in the thickness of the inferior and orbital frontal regions may be markers of specific BN symptoms. Because our sample size precluded correcting for multiple comparisons, these findings should be replicated in a larger sample. Future study of functional changes in associated fronto-striatal circuits could identify potential circuit-based intervention targets.

Scanning to conclusions? Visual attention to neutral faces under stress in individuals with and without subclinical paranoia

BACKGROUND AND OBJECTIVES

A promising candidate for a vulnerability indicator for psychosis is the restricted scanpath. Restricted scanning of social stimuli, such as faces, might also contribute to misinterpretations of facial expressions and thus increase the likelihood of delusional interpretations. Moreover, similar to other vulnerability indicators of psychosis, scanpaths may be susceptible to stress. Thus, we hypothesized that scanpath restriction would increase as a function of delusion-proneness, stress and their interaction.

METHODS

Participants were asked to look at neutral faces and rate their trustworthiness under a stress and a non-stress condition, while the eye gaze was recorded. The non-clinical sample was classified into low- and high-paranoia scorers using a median split. Eye-tracking parameters of interest were number of fixations, fixations within emotion-relevant facial areas, scanpath length and duration of fixations.

RESULTS

In general, high-paranoia scorers had a significantly shorter scanpath compared to low-paranoia scorers (F(1, 48) = 2.831, p = 0.05, η_p² = 0.056) and there was a trend towards a further decrease of scanpath length under stress in high-paranoia scorers relative to low-paranoia scorers (interaction effect: F(1, 48) = 2.638, p = 0.056, η_p² = 0.052). However, no effects were found for the other eye-tracking parameters. Moreover, trustworthiness ratings remained unaffected by group or condition.

LIMITATIONS

The participants of this study had only slight elevations of delusion-proneness, which might explain the absence of differences in trustworthiness ratings.

CONCLUSIONS

Restricted scanpaths appear to be partly present in individuals with subclinical levels of paranoia and appear to be susceptible to stress in this group. Nevertheless, further research in high-risk groups is necessary before drawing more definite conclusions.

Preserved implicit mentalizing in schizophrenia despite poor explicit performance: evidence from eye tracking

Schizophrenia has been characterized by an impaired mentalizing. It has been suggested that distinguishing implicit from explicit processes is crucial in social cognition, and only the latter might be affected in schizophrenia. Two other questions remain open: (1) Is schizophrenia characterized by an hypo- or hyper attribution of intentions? (2) Is it characterized by a deficit in the attribution of intention or of contingency? To test these three questions, spontaneous mentalizing was tested in 29 individuals with schizophrenia and 29 control subjects using the Frith-Happé animations, while eye movements were recorded. Explicit mentalizing was measured from participants’ verbal descriptions and was contrasted with implicit mentalizing measured through eye tracking. As a group, patients made less accurate and less intentional descriptions of the goal-directed and theory of mind animations. No group differences were found in the attribution of contingency. Eye tracking results revealed that patients and controls showed a similar modulation of eye movements in response to the mental states displayed in the Frith-Happé animations. To conclude, in this paradigm, participants with schizophrenia showed a dissociation between explicit and implicit mentalizing, with a decrease in the explicit attribution of intentions, whereas their eye movements suggested a preserved implicit perception of intentions.

Restricted attention to social cues in schizophrenia patients

Deficits of psychosocial functioning are a robust finding in schizophrenia. Research on social cognition may open a new avenue for the development of effective interventions. As a correlate of social perceptive information processing deficits, schizophrenia patients (SZP) show deviant gaze behavior (GB) while viewing emotional faces. As understanding of a social environment requires gathering complex social information, our study aimed at investigating the gaze behavior of SZP related to social interactions and its impact on the level of social and role functioning. GB of 32 SZP and 37 healthy control individuals (HCI) was investigated with a high-resolution eye tracker during an unguided viewing of 12 complex pictures of social interaction scenes. Regarding whole pictures, SZP showed a shorter scanpath length, fewer fixations and a shorter mean distance between fixations. Furthermore, SZP exhibited fewer and shorter fixations on faces, but not on the socially informative bodies nor on the background, suggesting a cue-specific abnormality. Logistic regression with bootstrapping yielded a model including two GB parameters; a subsequent ROC curve analysis indicated an excellent ability of group discrimination (AUC .85). Face-related GB aberrations correlated with lower social and role functioning and with delusional thinking, but not with negative symptoms. Training of spontaneous integration of face-related social information seems promising to enable a holistic perception of social information, which may in turn improve social and role functioning. The observed ability to discriminate SZP from HCI warrants further research on the predictive validity of GB in psychosis risk prediction.

The dysconnection hypothesis (2016)

Twenty years have passed since the dysconnection hypothesis was first proposed (Friston and Frith, 1995; Weinberger, 1993). In that time, neuroscience has witnessed tremendous advances: we now live in a world of non-invasive neuroanatomy, computational neuroimaging and the Bayesian brain. The genomics era has come and gone. Connectomics and large-scale neuroinformatics initiatives are emerging everywhere. So where is the dysconnection hypothesis now? This article considers how the notion of schizophrenia as a dysconnection syndrome has developed - and how it has been enriched by recent advances in clinical neuroscience. In particular, we examine the dysconnection hypothesis in the context of (i) theoretical neurobiology and computational psychiatry; (ii) the empirical insights afforded by neuroimaging and associated connectomics - and (iii) how bottom-up (molecular biology and genetics) and top-down (systems biology) perspectives are converging on the mechanisms and nature of dysconnections in schizophrenia.

Scene Construction, Visual Foraging, and Active Inference

This paper describes an active inference scheme for visual searches and the perceptual synthesis entailed by scene construction. Active inference assumes that perception and action minimize variational free energy, where actions are selected to minimize the free energy expected in the future. This assumption generalizes risk-sensitive control and expected utility theory to include epistemic value; namely, the value (or salience) of information inherent in resolving uncertainty about the causes of ambiguous cues or outcomes. Here, we apply active inference to saccadic searches of a visual scene. We consider the (difficult) problem of categorizing a scene, based on the spatial relationship among visual objects where, crucially, visual cues are sampled myopically through a sequence of saccadic eye movements. This means that evidence for competing hypotheses about the scene has to be accumulated sequentially, calling upon both prediction (planning) and postdiction (memory). Our aim is to highlight some simple but fundamental aspects of the requisite functional anatomy; namely, the link between approximate Bayesian inference under mean field assumptions and functional segregation in the visual cortex. This link rests upon the (neurobiologically plausible) process theory that accompanies the normative formulation of active inference for Markov decision processes. In future work, we hope to use this scheme to model empirical saccadic searches and identify the prior beliefs that underwrite intersubject variability in the way people forage for information in visual scenes (e.g., in schizophrenia).

Self-Face Recognition in Schizophrenia: An Eye-Tracking Study

Self-face recognition has been shown to be impaired in schizophrenia (SZ), according to studies using behavioral tasks implicating cognitive demands. Here, we employed an eye-tracking methodology, which is a relevant tool to understand impairments in self-face recognition deficits in SZ because it provides a natural, continuous and online record of face processing. Moreover, it allows collecting the most relevant and informative features each individual looks at during the self-face recognition. These advantages are especially relevant considering the fundamental role played by the patterns of visual exploration on face processing. Thus, this paper aims to investigate self-face recognition deficits in SZ using eye-tracking methodology. Visual scan paths were monitored in 20 patients with SZ and 20 healthy controls. Self, famous, and unknown faces were morphed in steps of 20%. Location, number, and duration of fixations on relevant areas were recorded with an eye-tracking system. Participants performed a passive exploration task (no specific instruction was provided), followed by an active decision making task (individuals were explicitly requested to recognize the different faces). Results showed that patients with SZ had fewer and longer fixations compared to controls. Nevertheless, both groups focused their attention on relevant facial features in a similar way. No significant difference was found between groups when participants were requested to recognize the faces (active task). In conclusion, using an eye tracking methodology and two tasks with low levels of cognitive demands, our results suggest that patients with SZ are able to: (1) explore faces and focus on relevant features of the face in a similar way as controls; and (2) recognize their own face.

Implicit emotion perception in schizophrenia

Explicit but not implicit facial emotion perception has been shown to be impaired in schizophrenia. In this study, we used newly developed technology in social neuroscience to examine implicit emotion processing. It has been shown that when people look at faces, they automatically infer social traits, and these trait judgments rely heavily on facial features and subtle emotion expressions even with neutral faces. Eighty-one individuals with schizophrenia or schizoaffective disorder and 62 control subjects completed a computer task with 30 well-characterized neutral faces. They rated each face on 10 trait judgments: attractive, mean, trustworthy, intelligent, dominant, fun, sociable, aggressive, emotionally stable and weird. The degree to which trait ratings were predicted by objectively-measured subtle emotion expressions served as a measure of implicit emotion processing. Explicit emotion recognition was also examined. Trait ratings were significantly predicted by subtle facial emotional expressions in controls and patients. However, impairment in the implicit emotion perception of fear, happiness, anger and surprise was found in patients. Moreover, these deficits were associated with poorer everyday problem-solving skills and were relatively independent of explicit emotion recognition. Implicit emotion processing is impaired in patients with schizophrenia or schizoaffective disorder. Deficits in implicit and explicit emotion perception independently contribute to the patients' poor daily life skills. More research is needed to fully understand the role of implicit and explicit processes in the functional deficits of patients, in order to develop targeted and useful remediation interventions.

Raising attention to attention deficit hyperactivity disorder in schizophrenia

Schizophrenia and attention deficit hyperactivity disorder (ADHD) are two psychiatric disorders with a negative impact on quality of life of individuals affected. Although they are classified into distinct disorders categories, attentional dysfunction is considered as a core feature in both conditions, either at the clinical then pathophysiological level. Beyond the obvious clinical overlap between these disorders, the Research Domain Criteria approach might offer an interesting perspective for disentangling common circuits underpinning both disorders. Hence, we review evidences regarding the overlap between schizophrenia and ADHD, at the clinical level, and at the level of underlying brain mechanisms. The evidence regarding the influence of environmental risk factors in the emergence of both disorders, and their developmental trajectories is also reviewed. Among these, we will try to elucidate the complex relationship between stimulants use and psychotic symptoms, discussing the potential role of ADHD medication in inducing psychosis or in exacerbating it. We aim that, taken together, these findings may promote further investigation with important implications both for clinicians and research. In fact, considering the amounting evidence on the overlap between schizophrenia and ADHD, the delineation of their boundaries might help in the decision for diagnosis and treatment. Moreover, it may help to promote interventions focused on the prevention of both schizophrenia and ADHD, by the reduction of recognized environmental risk factors.

Standing postural instability in patients with schizophrenia: Relationships with psychiatric symptoms, anxiety, and the use of neuroleptic medications

The purpose of this study was to assess postural instability in patients with schizophrenia using a pressure-sensitive platform and to examine the effects of anxiety, psychiatric symptoms, and the use of neuroleptic medications on postural sway. Participants were 23 patients with schizophrenia and 23 healthy controls. We found that the patients showed greater overall postural instability than the controls. Furthermore, they demonstrated greater instability when the test was performed with the eyes closed than with the eyes open. However, removal of visual input had less impact on the indices of postural instability in the patients than in the controls, suggesting that schizophrenia is associated with difficulties in integrating visual information and proprioceptive signals. Furthermore, in contrast to the controls, anxiety exacerbated postural instability in the patients. There were significant associations between postural stability and psychiatric symptoms in the patients without extrapyramidal symptoms, whereas medication dose did not significantly correlate with postural stability.

An eye-tracking investigation of intentional motion perception in patients with schizophrenia

BACKGROUND

Schizophrenia has been characterized by an impaired attribution of intentions in social interactions. However, it remains unclear to what extent poor performance may be due to low-level processes or to later, higher-level stages or to what extent the deficit reflects an over- (hypermentalization) or underattribution of intentions (hypomentalization).

METHODS

We evaluated intentional motion perception using a chasing detection paradigm in individuals with schizophrenia or schizoaffective disorder and in healthy controls while eye movements were recorded. Smooth pursuit was measured as a control task. Eye-tracking was used to dissociate ocular from cognitive stages of processing.

RESULTS

We included 27 patients with schizophrenia, 2 with schizoaffective disorder and 29 controls in our analysis. As a group, patients had lower sensitivity to the detection of chasing than controls, but showed no bias toward the chasing present response. Patients showed a slightly different visual exploration strategy, which affected their ocular sensitivity to chasing. They also showed a decreased cognitive sensitivity to chasing that was not explained by differences in smooth pursuit ability, in visual exploration strategy or in general cognitive abilities.

LIMITATIONS

It is not clear whether the deficit in intentional motion detection demonstrated in this study might be explained by a general deficit in motion perception in individuals with schizophrenia or whether it is specific to the social domain.

CONCLUSION

Participants with schizophrenia showed a hypomentalization deficit: they adopted suboptimal visual exploration strategies and had difficulties deciding whether a chase was present or not, even when their eye movement revealed that chasing information had been seen correctly.

Excessive checking behavior during an image comparison task in schizophrenia

BACKGROUND

Patients with schizophrenia display significant working memory and executive deficits. In patients with obsessive-compulsive disorder (OCD), several studies suggest that working memory dysfunction may be one of the causes of compulsive checking behaviors. Hence, this study aimed at assessing whether patients with schizophrenia were impaired on an image comparison task used to measure checking behaviors, and whether the origin and profile of impairment on this task was different between schizophrenia and OCD.

METHODS

Eye movement recordings were used to assess the checking behavior of 24 patients with schizophrenia and 24 control participants who had to decide whether two images were different or identical. The verbal and visuo-spatial components of participants' working memory were measured using the reading span and backward location span tests.

RESULTS

Compared to controls, patients with schizophrenia had reduced working memory spans and showed excessive checking behavior when comparing the two images. However, the intensity of their checking behavior was not significantly related to their working memory deficits.

CONCLUSIONS

Several recent studies demonstrated that the excessive checking behaviors displayed by patients with OCD were related to working memory dysfunction. The absence of a relationship between the excessive checking behavior of patients with schizophrenia and their working memory deficits suggests that checking behaviors do not have the same origin in the two disorders.

Visual attention to emotional face in schizophrenia: an eye tracking study

OBJECTIVE

Deficits in the processing of facial emotions have been reported extensively in patients with schizophrenia. To explore whether restricted attention is the cause of impaired emotion processing in these patients, we examined visual attention through tracking eye movements in response to emotional and neutral face stimuli in a group of patients with schizophrenia and healthy individuals. We also examined the correlation between visual attention allocation and symptoms severity in our patient group.

METHOD

Thirty adult patients with schizophrenia and 30 matched healthy controls participated in this study. Visual attention data were recorded while participants passively viewed emotional-neutral face pairs for 500 ms. The relationship between the visual attention and symptoms severity were assessed by the Positive and Negative Syndrome Scale (PANSS) in the schizophrenia group. Repeated Measures ANOVAs were used to compare the groups.

RESULTS

Comparing the number of fixations made during face-pairs presentation, we found that patients with schizophrenia made fewer fixations on faces, regardless of the expression of the face. Analysis of the number of fixations on negative-neutral pairs also revealed that the patients made fewer fixations on both neutral and negative faces. Analysis of number of fixations on positive-neutral pairs only showed more fixations on positive relative to neutral expressions in both groups. We found no correlations between visual attention pattern to faces and symptom severity in schizophrenic patients.

CONCLUSION

The results of this study suggest that the facial recognition deficit in schizophrenia is related to decreased attention to face stimuli. Finding of no difference in visual attention for positive-neutral face pairs between the groups is in line with studies that have shown increased ability to positive emotional perception in these patients.

Altered integrity of the right arcuate fasciculus as a trait marker of schizophrenia: a sibling study using tractography-based analysis of the whole brain

Trait markers of schizophrenia aid the dissection of the heterogeneous phenotypes into distinct subtypes and facilitate the genetic underpinning of the disease. The microstructural integrity of the white matter tracts could serve as a trait marker of schizophrenia, and tractography-based analysis (TBA) is the current method of choice. Manual tractography is time-consuming and limits the analysis to preselected fiber tracts. Here, we sought to identify a trait marker of schizophrenia from among 74 fiber tracts across the whole brain using a novel automatic TBA method. Thirty-one patients with schizophrenia, 31 unaffected siblings and 31 healthy controls were recruited to undergo diffusion spectrum magnetic resonance imaging at 3T. Generalized fractional anisotropy (GFA), an index reflecting tract integrity, was computed for each tract and compared among the three groups. Ten tracts were found to exhibit significant differences between the groups with a linear, stepwise order from controls to siblings to patients; they included the right arcuate fasciculus, bilateral fornices, bilateral auditory tracts, left optic radiation, the genu of the corpus callosum, and the corpus callosum to the bilateral dorsolateral prefrontal cortices, bilateral temporal poles, and bilateral hippocampi. Posthoc between-group analyses revealed that the GFA of the right arcuate fasciculus was significantly decreased in both the patients and unaffected siblings compared to the controls. Furthermore, the GFA of the right arcuate fasciculus exhibited a trend toward positive symptom scores. In conclusion, the right arcuate fasciculus may be a candidate trait marker and deserves further study to verify any genetic association.

Effects of Training of Affect Recognition on the recognition and visual exploration of emotional faces in schizophrenia

BACKGROUND

Schizophrenia patients have impairments in facial affect recognition and display scanpath abnormalities during the visual exploration of faces. These abnormalities are characterized by fewer fixations on salient feature areas and longer fixation durations. The present study investigated whether social-cognitive remediation not only improves performance in facial affect recognition but also normalizes patients' gaze behavior while looking at faces.

METHODS

Within a 2 × 2-design (group × time), 16 schizophrenia patients and 16 healthy controls performed a facial affect recognition task with concomitant infrared oculography at baseline (T0) and after six weeks (T1). Between the measurements, patients completed the Training of Affect Recognition (TAR) program. The influence of the training on facial affect recognition (percent of correct answers) and gaze behavior (number and mean duration of fixations into salient or non-salient facial areas) was assessed.

RESULTS

In line with former studies, at baseline patients showed poorer facial affect recognition than controls and aberrant scanpaths, and after TAR facial affect recognition was improved. Concomitant with improvements in performance, the number of fixations in feature areas ('mouth') increased while fixations in non-feature areas ('white space') decreased. However, the change in fixation behavior did not correlate with the improvement in performance.

CONCLUSIONS

After TAR, patients pay more attention to facial areas that contain information about a displayed emotion. Although this may contribute to the improved performance, the lack of a statistical correlation implies that this factor is not sufficient to explain the underlying mechanism of the treatment effect.

Relationship between abstract thinking and eye gaze pattern in patients with schizophrenia

Background

Effective integration of visual information is necessary to utilize abstract thinking, but patients with schizophrenia have slow eye movement and usually explore limited visual information. This study examines the relationship between abstract thinking ability and the pattern of eye gaze in patients with schizophrenia using a novel theme identification task.

Methods

Twenty patients with schizophrenia and 22 healthy controls completed the theme identification task, in which subjects selected which word, out of a set of provided words, best described the theme of a picture. Eye gaze while performing the task was recorded by the eye tracker.

Results

Patients exhibited a significantly lower correct rate for theme identification and lesser fixation and saccade counts than controls. The correct rate was significantly correlated with the fixation count in patients, but not in controls.

Conclusions

Patients with schizophrenia showed impaired abstract thinking and decreased quality of gaze, which were positively associated with each other. Theme identification and eye gaze appear to be useful as tools for the objective measurement of abstract thinking in patients with schizophrenia.

Eye-head coordination abnormalities in schizophrenia

BACKGROUND

Eye-movement abnormalities in schizophrenia are a well-established phenomenon that has been observed in many studies. In such studies, visual targets are usually presented in the center of the visual field, and the subject's head remains fixed. However, in every-day life, targets may also appear in the periphery. This study is among the first to investigate eye and head movements in schizophrenia by presenting targets in the periphery of the visual field.

METHODOLOGY/PRINCIPAL FINDINGS

Two different visual recognition tasks, color recognition and Landolt orientation tasks, were presented at the periphery (at a visual angle of 55° from the center of the field of view). Each subject viewed 96 trials, and all eye and head movements were simultaneously recorded using video-based oculography and magnetic motion tracking of the head. Data from 14 patients with schizophrenia and 14 controls were considered. The patients had similar saccadic latencies in both tasks, whereas controls had shorter saccadic latencies in the Landolt task. Patients performed more head movements, and had increased eye-head offsets during combined eye-head shifts than controls.

CONCLUSIONS/SIGNIFICANCE

Patients with schizophrenia may not be able to adapt to the two different tasks to the same extent as controls, as seen by the former's task-specific saccadic latency pattern. This can be interpreted as a specific oculomotoric attentional dysfunction and may support the hypothesis that schizophrenia patients have difficulties determining the relevance of stimuli. Patients may also show an uneconomic over-performance of head-movements, which is possibly caused by alterations in frontal executive function that impair the inhibition of head shifts. In addition, a model was created explaining 93% of the variance of the response times as a function of eye and head amplitude, which was only observed in the controls, indicating abnormal eye-head coordination in patients with schizophrenia.