Deficient biological motion perception in schizophrenia: results from a motion noise paradigm

Atypical local and global biological motion perception in children with attention deficit hyperactivity disorder

Perceiving biological motion (BM) is crucial for human survival and social interaction. Many studies have reported impaired BM perception in autism spectrum disorder, which is characterised by deficits in social interaction. Children with attention deficit hyperactivity disorder (ADHD) often exhibit similar difficulties in social interaction. However, few studies have investigated BM perception in children with ADHD. Here, we compared differences in the ability to process local kinematic and global configurational cues, two fundamental abilities of BM perception, between typically developing and ADHD children. We further investigated the relationship between BM perception and social interaction skills measured using the Social Responsiveness Scale and examined the contributions of latent factors (e.g. sex, age, attention, and intelligence) to BM perception. The results revealed that children with ADHD exhibited atypical BM perception. Local and global BM processing showed distinct features. Local BM processing ability was related to social interaction skills, whereas global BM processing ability significantly improved with age. Critically, general BM perception (i.e. both local and global BM processing) may be affected by sustained attentional ability in children with ADHD. This relationship was primarily mediated by reasoning intelligence. These findings elucidate atypical BM perception in ADHD and the latent factors related to BM perception. Moreover, this study provides new evidence that BM perception is a hallmark of social cognition and advances our understanding of the potential roles of local and global processing in BM perception and social cognitive disorders.

Interaction between spatial perception and temporal perception enables preservation of cause-effect relationship: Visual psychophysics and neuronal dynamics

INTRODUCTION

Visual perception of moving objects is integral to our day-to-day life, integrating visual spatial and temporal perception. Most research studies have focused on finding the brain regions activated during motion perception. However, an empirically validated general mathematical model is required to understand the modulation of the motion perception. Here, we develop a mathematical formulation of the modulation of the perception of a moving object due to a change in speed, under the formulation of the invariance of causality.

METHODS

We formulated the perception of a moving object as the coordinate transformation from a retinotopic space onto perceptual space and derived a quantitative relationship between spatiotemporal coordinates. To validate our model, we undertook the analysis of two experiments: (i) the perceived length of the moving arc, and (ii) the perceived time while observing moving stimuli. We performed a magnetic resonance imaging (MRI) tractography investigation of subjects to demarcate the anatomical correlation of the modulation of the perception of moving objects.

RESULTS

Our theoretical model shows that the interaction between visual-spatial and temporal perception, during the perception of moving object is described by coupled linear equations; and experimental observations validate our model. We observed that cerebral area V5 may be an anatomical correlate for this interaction. The physiological basis of interaction is shown by a Lotka-Volterra system delineating interplay between acetylcholine and dopamine neurotransmitters, whose concentrations vary periodically with the orthogonal phase shift between them, occurring at the axodendritic synapse of complex cells at area V5.

CONCLUSION

Under the invariance of causality in the representation of events in retinotopic space and perceptual space, the speed modulates the perception of a moving object. This modulation may be due to variations of the tuning properties of complex cells at area V5 due to the dynamic interaction between acetylcholine and dopamine. Our analysis is the first significant study, to our knowledge, that establishes a mathematical linkage between motion perception and causality invariance.

Using dynamic point light display stimuli to assess gesture deficits in schizophrenia

Background

Gesture deficits are ubiquitous in schizophrenia patients contributing to poor social communication and functional outcome. Given the dynamic nature of social communications, the current study aimed to explore the underlying socio-cognitive processes associated with point-light-displays (PLDs) of communicative gestures in the absence of any other confounding visual characteristics, and compare them to other well-established stimuli of gestures such as pictures by examining their association with symptom severity and motor-cognitive modalities.

Methods

We included 39-stable schizophrenia outpatients and 27-age-gender matched controls and assessed gesture processing using two tasks. The first task used static stimuli of pictures of a person performing a gesture. The limbs executing the gesture were missing and participants' task was to choose the correct gesture from three-options provided. The second task included videos of dynamic PLDs interacting with each other. One PLD performed communicative gestures, while the other PLD imitated/followed these performed gestures. Participants had to indicate, which of the two PLDs was imitating/following the other. Additionally, we evaluated symptom severity, as well as, motor and cognitive parameters.

Results

Patients underperformed in both gesture tasks compared to controls. Task performance for static stimuli was associated with blunted affect, motor coordination and sequencing domains, while PLD performance was associated with expressive gestures and sensory integration processes.

Discussion

Gesture representations of static and dynamic stimuli are associated with distinct processes contributing to poor social communication in schizophrenia, requiring novel therapeutic interventions. Such stimuli can easily be applied remotely for screening socio-cognitive deficits in schizophrenia.

Deficits in Working Memory and Theory of Mind May Underlie Difficulties in Social Perception of Children with ADHD

Children with attention deficit hyperactivity disorder (ADHD) are prone to peer rejection and disliking due to difficulties in social perception and interaction. To address social perception impairments in ADHD, we examined children with ADHD in a noisy biological motion (BM) direction discrimination paradigm in association with sociocognitive factors including emotion regulation, theory of mind (TOM), and working memory compared to healthy controls. Our results showed that children with ADHD were poorer in discriminating BM direction in noisy environments (F (1, 36) = 4.655, p=0.038). Moreover, a significant correlation was found between working memory and TOM with BM discrimination in an ADHD group (r = 0.442, p=0.01, and r = 0.403, p=0.05, respectively). Our findings could suggest that social perception in noisy scenarios may be affected by memory and social cognitive abilities of children with ADHD.

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.

Consensus Paper: Cerebellum and Social Cognition

The traditional view on the cerebellum is that it controls motor behavior. Although recent work has revealed that the cerebellum supports also nonmotor functions such as cognition and affect, only during the last 5 years it has become evident that the cerebellum also plays an important social role. This role is evident in social cognition based on interpreting goal-directed actions through the movements of individuals (social "mirroring") which is very close to its original role in motor learning, as well as in social understanding of other individuals' mental state, such as their intentions, beliefs, past behaviors, future aspirations, and personality traits (social "mentalizing"). Most of this mentalizing role is supported by the posterior cerebellum (e.g., Crus I and II). The most dominant hypothesis is that the cerebellum assists in learning and understanding social action sequences, and so facilitates social cognition by supporting optimal predictions about imminent or future social interaction and cooperation. This consensus paper brings together experts from different fields to discuss recent efforts in understanding the role of the cerebellum in social cognition, and the understanding of social behaviors and mental states by others, its effect on clinical impairments such as cerebellar ataxia and autism spectrum disorder, and how the cerebellum can become a potential target for noninvasive brain stimulation as a therapeutic intervention. We report on the most recent empirical findings and techniques for understanding and manipulating cerebellar circuits in humans. Cerebellar circuitry appears now as a key structure to elucidate social interactions.

A meta-analysis of the associations between theory of mind and neurocognition in schizophrenia

Theory of mind (ToM) refers to the ability to infer the mental states of others. ToM is impaired in schizophrenia and these deficits seem to hinder functional recovery. ToM is thus an important, but complex treatment target, supported by several processes. A large number of studies report significant associations between ToM and neurocognition (e.g. memory, attention), but the neurocognitive domains that are most closely linked to ToM remain to be identified. A meta-analysis was conducted to estimate the magnitude of the associations between ToM and neurocognition in people with schizophrenia. Correlations were extracted from the relevant literature, transformed into effect sizes Zr and pooled as weighted means. Focused-tests were employed to test for differences between neurocognitive domains and for differences linked to the characteristics of ToM tasks. Ninety-one studies (N = 5462) were included. Moderate associations emerged between ToM and each neurocognitive domain (Zrs 0.27-0.43), with no significant difference between domains (χ2(8) = 11.89, p = 0.156). Within the domain of executive functions, abstraction showed a stronger association with ToM (χ2(4) = 18.93, p = 0.001). Several ToM tasks characteristics (e.g. modality of stimuli, type of mental state), were significantly related to the magnitude of the associations between ToM and executive functions, visuospatial/problem solving, attention and episodic memory. These results suggest that ToM is linked to a wide range of neurocognitive abilities in schizophrenia, and that ToM tasks are a significant moderator of these associations. The assessment and treatment of ToM should consider the neurocognitive profile of each patient to understand his difficulties and to tailor interventions.

Structural and effective brain connectivity underlying biological motion detection

The perception of actions underwrites a wide range of socio-cognitive functions. Previous neuroimaging and lesion studies identified several components of the brain network for visual biological motion (BM) processing, but interactions among these components and their relationship to behavior remain little understood. Here, using a recently developed integrative analysis of structural and effective connectivity derived from high angular resolution diffusion imaging (HARDI) and functional magnetic resonance imaging (fMRI), we assess the cerebro-cerebellar network for processing of camouflaged point-light BM. Dynamic causal modeling (DCM) informed by probabilistic tractography indicates that the right superior temporal sulcus (STS) serves as an integrator within the temporal module. However, the STS does not appear to be a "gatekeeper" in the functional integration of the occipito-temporal and frontal regions: The fusiform gyrus (FFG) and middle temporal cortex (MTC) are also connected to the right inferior frontal gyrus (IFG) and insula, indicating multiple parallel pathways. BM-specific loops of effective connectivity are seen between the left lateral cerebellar lobule Crus I and right STS, as well as between the left Crus I and right insula. The prevalence of a structural pathway between the FFG and STS is associated with better BM detection. Moreover, a canonical variate analysis shows that the visual sensitivity to BM is best predicted by BM-specific effective connectivity from the FFG to STS and from the IFG, insula, and STS to the early visual cortex. Overall, the study characterizes the architecture of the cerebro-cerebellar network for BM processing and offers prospects for assessing the social brain.

Intact perception of coherent motion, dynamic rigid form, and biological motion in chronic schizophrenia

BACKGROUND

Prior studies have documented biological motion perception deficits in schizophrenia, but it remains unclear whether the impairments arise from poor social cognition, perceptual organization, basic motion processing, or sustained attention/motivation. To address the issue, we had 24 chronic schizophrenia patients and 27 healthy controls perform three tasks: coherent motion, where subjects indicated whether a cloud of dots drifted leftward or rightward; dynamic rigid form, where subjects determined the tilt direction of a translating, point-light rectangle; and biological motion, where subjects judged whether a human point-light figure walked leftward or rightward. Task difficulty was staircase controlled and depended on the directional variability of the background dot motion. Catch trials were added to verify task attentiveness and engagement.

RESULTS

Patients and controls demonstrated similar performance thresholds and near-ceiling catch trial accuracy for each task (uncorrected ps > 0.1; ds < 0.35). In all but the coherent motion task, higher IQ correlated with better performance (ps < 0.001).

CONCLUSION

Schizophrenia patients have intact perception of motion coherence, dynamic rigid form, and biological motion at least for our sample and set-up. We speculate that previously documented biological motion perception deficits arose from task or stimulus differences or from group differences in IQ, attention, or motivation.

Seeing the World as it is: Mimicking Veridical Motion Perception in Schizophrenia Using Non-invasive Brain Stimulation in Healthy Participants

Schizophrenia (Sz) is a mental health disorder characterized by severe cognitive, emotional, social, and perceptual deficits. Visual deficits are found in tasks relying on the magnocellular/dorsal stream. In our first experiment we established deficits in global motion processing in Sz patients compared to healthy controls. We used a novel task in which background optic flow produces a distortion of the apparent trajectory of a moving stimulus, leading control participants to provide biased estimates of the true motion trajectory under conditions of global stimulation. Sz patients were significantly less affected by the global background motion, and reported trajectories that were more veridically accurate than those of controls. In order to study the mechanism of this effect, we performed a second experiment where we applied transcranial electrical stimulation over area MT+ to selectively modify global motion processing of optic flow displays in healthy participants. Cathodal and high frequency random noise stimulation had opposite effects on trajectory perception in optic flow. The brain stimulation over a control site and in a control task revealed that the effect of stimulation was specific for global motion processing in area MT+. These findings both support prior studies of impaired early visual processing in Sz and provide novel approaches for measurement and manipulation of the underlying circuits.

It Is Not Just in Faces! Processing of Emotion and Intention from Biological Motion in Psychiatric Disorders

Social neuroscience offers a wide range of techniques that may be applied to study the social cognitive deficits that may underlie reduced social functioning—a common feature across many psychiatric disorders. At the same time, a significant proportion of research in this area has been conducted using paradigms that utilize static displays of faces or eyes. The use of point-light displays (PLDs) offers a viable alternative for studying recognition of emotion or intention inference while minimizing the amount of information presented to participants. This mini-review aims to summarize studies that have used PLD to study emotion and intention processing in schizophrenia (SCZ), affective disorders, anxiety and personality disorders, eating disorders and neurodegenerative disorders. Two main conclusions can be drawn from the reviewed studies: first, the social cognitive problems found in most of the psychiatric samples using PLD were of smaller magnitude than those found in studies presenting social information using faces or voices. Second, even though the information presented in PLDs is extremely limited, presentation of these types of stimuli is sufficient to elicit the disorder-specific, social cognitive biases (e.g., mood-congruent bias in depression, increased threat perception in anxious individuals, aberrant body size perception in eating disorders) documented using other methodologies. Taken together, these findings suggest that point-light stimuli may be a useful method of studying social information processing in psychiatry. At the same time, some limitations of using this methodology are also outlined.

Biological motion processing in schizophrenia - Systematic review and meta-analysis

CONTEXT

Patients with schizophrenia show impairments in processing of biological motion. This is especially important since deficits in domains of social cognition has been associated with functional outcome and everyday functioning in this population.

OBJECTIVES

We conducted a systematic review and meta-analysis of studies which have used point-light displays to present whole-body motion to patients with schizophrenia and healthy controls, to evaluate the magnitude of differences between these groups in biological motion processing.

METHOD

Firstly, relevant publications were identified by a systematic search of Google Scholar and PubMed databases. Secondly, we excluded non-relevant studies for the meta-analysis according to our exclusion criteria. Effect sizes were expressed as standardized mean difference (SMD).

RESULTS

15 papers reporting results of 14 different experiments with 571 patients and 482 controls were included in the meta-analysis. The results for the general biological motion perception analysis revealed that patients with schizophrenia (compared with healthy controls) present reduced biological motion processing capacity with the effect size (SMD) of 0.66 (95% CI, -0.79 to -0.54; p<0.001). The results for the specific biological motion-based tasks were also statistically significant with SMD of 0.72 for Basic Biological Motion task (95% CI: -0.94 to -0.51; p<0.001) and SMD of 0.61 for Emotion in Biological Motion task, (95% CI: -0.79 to -0.43; p<0.001) respectively.

CONCLUSION

The findings from our meta-analysis highlight abnormalities in general and specific domains of biological motion perception in schizophrenia patients as compared with healthy controls.

A Causal Role of the Right Superior Temporal Sulcus in Emotion Recognition From Biological Motion

Understanding the emotions of others through nonverbal cues is critical for successful social interactions. The right posterior superior temporal sulcus (pSTS) is one brain region thought to be key in the recognition of the mental states of others based on body language and facial expression. In the present study, we temporarily disrupted functional activity of the right pSTS by using continuous, theta-burst transcranial magnetic stimulation (cTBS) to test the hypothesis that the right pSTS plays a causal role in emotion recognition from body movements. Participants ( N = 23) received cTBS to the right pSTS, which was individually localized using fMRI, and a vertex control site. Before and after cTBS, we tested participants’ ability to identify emotions from point-light displays (PLDs) of biological motion stimuli and a nonbiological global motion identification task. Results revealed that accurate identification of emotional states from biological motion was reduced following cTBS to the right pSTS, but accuracy was not impaired following vertex stimulation. Accuracy on the global motion task was unaffected by cTBS to either site. These results support the causal role of the right pSTS in decoding information about others’ emotional state from their body movements and gestures.

Behavioural evidence for distinct mechanisms related to global and biological motion perception

The perception of human motion is a vital ability in our daily lives. Human movement recognition is often studied using point-light stimuli in which dots represent the joints of a moving person. Depending on task and stimulus, the local motion of the single dots, and the global form of the stimulus can be used to discriminate point-light stimuli. Previous studies often measured motion coherence for global motion perception and contrasted it with performance in biological motion perception to assess whether difficulties in biological motion processing are related to more general difficulties with motion processing. However, it is so far unknown as to how performance in global motion tasks relates to the ability to use local motion or global form to discriminate point-light stimuli. Here, we investigated this relationship in more detail. In Experiment 1, we measured participants' ability to discriminate the facing direction of point-light stimuli that contained primarily local motion, global form, or both. In Experiment 2, we embedded point-light stimuli in noise to assess whether previously found relationships in task performance are related to the ability to detect signal in noise. In both experiments, we also assessed motion coherence thresholds from random-dot kinematograms. We found relationships between performances for the different biological motion stimuli, but performance for global and biological motion perception was unrelated. These results are in accordance with previous neuroimaging studies that highlighted distinct areas for global and biological motion perception in the dorsal pathway, and indicate that results regarding the relationship between global motion perception and biological motion perception need to be interpreted with caution.

Load-sensitive impairment of working memory for biological motion in schizophrenia

Impaired working memory (WM) is a core cognitive deficit in schizophrenia. Nevertheless, past studies have reported that patients may also benefit from increasing salience of memory stimuli. Such efficient encoding largely depends upon precise perception. Thus an investigation on the relationship between perceptual processing and WM would be worthwhile. Here, we used biological motion (BM), a socially relevant stimulus that schizophrenics have difficulty discriminating from similar meaningless motions, in a delayed-response task. Non-BM stimuli and static polygons were also used for comparison. In each trial, one of the three types of stimuli was presented followed by two probes, with a short delay in between. Participants were asked to indicate whether one of them was identical to the memory item or both were novel. The number of memory items was one or two. Healthy controls were more accurate in recognizing BM than non-BM regardless of memory loads. Patients with schizophrenia exhibited similar accuracy patterns to those of controls in the Load 1 condition only. These results suggest that information contained in BM could facilitate WM encoding in general, but the effect is vulnerable to the increase of cognitive load in schizophrenia, implying inefficient encoding driven by imprecise perception.

Dopaminergic Modulation of Biological Motion Perception in patients with Parkinson's disease

Parkinson’s disease (PD) is a progressive neurodegenerative disorder pathologically characterized by a selective loss of dopaminergic neurons in the substantia nigra. In previous studies, greater attention was paid to impairments in motor disturbances in contrast to impairments of cognitive function in PD that was often ignored. In present study, a duration discrimination paradigm was used to assess global and local biological motion (BM) perception in healthy controls(HCs) and PD patients with and without dopamine substitution treatment (DST). Biological motion sequences and inanimate motion sequences (inverted BM sequences) were sequentially presented on a screen. Observers were required to verbally make a 2-alternative forced-choice to indicate whether the first or second interval appeared longer. The stimuli involved global and local BM sequences. Statistical analyses were conducted on points of subjective equality (PSE). We found significant differences between untreated PD patients and HCs as well as differences between global and local BM conditions. PD patients have a deficit in both global and local BM perception. Nevertheless, these two BM conditions can be improved under DST. Our data indicates that BM perception may be damaged in PD patients and dopaminergic medication is conducive to maintain the BM perception in PD patients.

Neural basis of altered earlier attention and higher order biological motion processing in schizophrenia

Schizophrenia patients have impairments of biological motion (BM) perception, which provides critical information about social cognition. Because social cognition is underpinned by attention, the impairments of BM perception in schizophrenia could be partially attributable to altered attention. To elucidate the impairments in attention and social perception in schizophrenia, we investigated the neural basis of impaired BM processing using MRI in respect to attention deficits by eye tracker. Voxel-based morphometry was performed to evaluate the relationship between BM perception and gray matter (GM) volume. The temporo-parietal junction (TPJ) and anterior superior temporal sulcus (aSTS) were related to task accuracy. However, when the effect of attention (i.e., eye movement) was controlled, the relationship in TPJ became non-significant, while aSTS showed a significant relationship with BM perception. Alteration in TPJ might be associated with inefficient attentional strategy, whereas dysfunctional aSTS might be correlated with deficit in higher order BM processing per se. Several cognitive levels as well as corresponding brain areas are possibly involved in the manifestation of social cognitive deficits in schizophrenia.

Dopamine Activation Preserves Visual Motion Perception Despite Noise Interference of Human V5/MT

When processing sensory signals, the brain must account for noise, both noise in the stimulus and that arising from within its own neuronal circuitry. Dopamine receptor activation is known to enhance both visual cortical signal-to-noise-ratio (SNR) and visual perceptual performance; however, it is unknown whether these two dopamine-mediated phenomena are linked. To assess this, we used single-pulse transcranial magnetic stimulation (TMS) applied to visual cortical area V5/MT to reduce the SNR focally and thus disrupt visual motion discrimination performance to visual targets located in the same retinotopic space. The hypothesis that dopamine receptor activation enhances perceptual performance by improving cortical SNR predicts that dopamine activation should antagonize TMS disruption of visual perception. We assessed this hypothesis via a double-blinded, placebo-controlled study with the dopamine receptor agonists cabergoline (a D2 agonist) and pergolide (a D1/D2 agonist) administered in separate sessions (separated by 2 weeks) in 12 healthy volunteers in a William's balance-order design. TMS degraded visual motion perception when the evoked phosphene and the visual stimulus overlapped in time and space in the placebo and cabergoline conditions, but not in the pergolide condition. This suggests that dopamine D1 or combined D1 and D2 receptor activation enhances cortical SNR to boost perceptual performance. That local visual cortical excitability was unchanged across drug conditions suggests the involvement of long-range intracortical interactions in this D1 effect. Because increased internal noise (and thus lower SNR) can impair visual perceptual learning, improving visual cortical SNR via D1/D2 agonist therapy may be useful in boosting rehabilitation programs involving visual perceptual training.

SIGNIFICANCE STATEMENT

In this study, we address the issue of whether dopamine activation improves visual perception despite increasing sensory noise in the visual cortex. We show specifically that dopamine D1 (or combined D1/D2) receptor activation enhances the cortical signal-to-noise-ratio to boost perceptual performance. Together with the previously reported effects of dopamine upon brain plasticity and learning (Wolf et al., 2003; Hansen and Manahan-Vaughan, 2014), our results suggest that combining rehabilitation with dopamine agonists could enhance both the saliency of the training signal and the long-term effects on brain plasticity to boost rehabilitation regimens for brain injury.

The Cerebellum: Adaptive Prediction for Movement and Cognition

Over the past 30 years, cumulative evidence has indicated that cerebellar function extends beyond sensorimotor control. This view has emerged from studies of neuroanatomy, neuroimaging, neuropsychology, and brain stimulation, with the results implicating the cerebellum in domains as diverse as attention, language, executive function, and social cognition. Although the literature provides sophisticated models of how the cerebellum helps refine movements, it remains unclear how the core mechanisms of these models can be applied when considering a broader conceptualization of cerebellar function. In light of recent multidisciplinary findings, we examine how two key concepts that have been suggested as general computational principles of cerebellar function- prediction and error-based learning- might be relevant in the operation of cognitive cerebro-cerebellar loops.

Facilitating Effects of Emotion on the Perception of Biological Motion: Evidence for a Happiness Superiority Effect

It has been reported that visual perception can be influenced not only by the physical features of a stimulus but also by the emotional valence of the stimulus, even without explicit emotion recognition. Some previous studies reported an anger superiority effect while others found a happiness superiority effect during visual perception. It thus remains unclear as to which emotion is more influential. In the present study, we conducted two experiments using biological motion (BM) stimuli to examine whether emotional valence of the stimuli would affect BM perception; and if so, whether a specific type of emotion is associated with a superiority effect. Point-light walkers with three emotion types (anger, happiness, and neutral) were used, and the threshold to detect BM within noise was measured in Experiment 1. Participants showed higher performance in detecting happy walkers compared with the angry and neutral walkers. Follow-up motion velocity analysis revealed that physical difference among the stimuli was not the main factor causing the effect. The results of the emotion recognition task in Experiment 2 also showed a happiness superiority effect, as in Experiment 1. These results show that emotional valence (happiness) of the stimuli can facilitate the processing of BM.

You looking at me?: Interpreting social cues in schizophrenia

BACKGROUND

Deficits in the perception of social cues are common in schizophrenia and predict functional outcome. While effective communication depends on deciphering both verbal and non-verbal features, work on non-verbal communication in the disorder is scarce.

METHOD

This behavioural study of 29 individuals with schizophrenia and 25 demographically matched controls used silent video-clips to examine gestural identification, its contextual modulation and related metacognitive representations.

RESULTS

In accord with our principal hypothesis, we observed that individuals with schizophrenia exhibited a preserved ability to identify archetypal gestures and did not differentially infer communicative intent from incidental movements. However, patients were more likely than controls to perceive gestures as self-referential when confirmatory evidence was ambiguous. Furthermore, the severity of their current hallucinatory experience inversely predicted their confidence ratings associated with these self-referential judgements.

CONCLUSIONS

These findings suggest a deficit in the contextual refinement of social-cue processing in schizophrenia that is potentially attributable to impaired monitoring of a mirror mechanism underlying intentional judgements, or to an incomplete semantic representation of gestural actions. Non-verbal communication may be improved in patients through psychotherapeutic interventions that include performance and perception of gestures in group interactions.

Complexities of emotional responses to social and non-social affective stimuli in schizophrenia

BACKGROUND

Adaptive emotional responses are important in interpersonal relationships. We investigated self-reported emotional experience, physiological reactivity, and micro-facial expressivity in relation to the social nature of stimuli in individuals with schizophrenia (SZ).

METHOD

Galvanic skin response (GSR) and facial electromyography (fEMG) were recorded in medicated outpatients with SZ and demographically matched healthy controls (CO) while they viewed social and non-social images from the International Affective Pictures System. Participants rated the valence and arousal, and selected a label for experienced emotions. Symptom severity in the SZ and psychometric schizotypy in CO were assessed.

RESULTS

The two groups did not differ in their labeling of the emotions evoked by the stimuli, but individuals with SZ were more positive in their valence ratings. Although self-reported arousal was similar in both groups, mean GSR was greater in SZ, suggesting differential awareness, or calibration of internal states. Both groups reported social images to be more arousing than non-social images but their physiological responses to non-social vs. social images were different. Self-reported arousal to neutral social images was correlated with positive symptoms in SZ. Negative symptoms in SZ and disorganized schizotypy in CO were associated with reduced mean fEMG. Greater corrugator mean fEMG activity for positive images in SZ indicates valence-incongruent facial expressions.

CONCLUSION

The patterns of emotional responses differed between the two groups. While both groups were in broad agreement in self-reported arousal and emotion labels, their mean GSR, and fEMG correlates of emotion diverged in relation to the social nature of the stimuli and clinical measures. Importantly, these results suggest disrupted self awareness of internal states in SZ and underscore the complexities of emotion processing in health and disease.

Specific vulnerability of face perception to noise: a similar effect in schizophrenia patients and healthy individuals

Face perception plays a foundational role in the social world. This perceptual ability is deficient in schizophrenia. A noise-filtering mechanism is essential for perceptual processing. It remains unclear as to whether a specific noise-filtering mechanism is implicated in the face perception problem or a general noise-filtering mechanism is involved which also mediates non-face visual perception problems associated with this psychiatric disorder. This study examined and compared the effects of external noise on the performance of face discrimination and car discrimination in schizophrenia patients (n=25) and healthy controls (n=27). Superimposing the external visual noise on face or car stimuli elevated perceptual thresholds (i.e. degraded performance levels) for both face and car discrimination. However, the effect of noise was significantly larger on face than on car discrimination, both in patients and controls. This pattern of results suggests specific vulnerability of face processing to noise in healthy individuals and those with schizophrenia.

Local and global limits on visual processing in schizophrenia

Schizophrenia has been linked to impaired performance on a range of visual processing tasks (e.g. detection of coherent motion and contour detection). It has been proposed that this is due to a general inability to integrate visual information at a global level. To test this theory, we assessed the performance of people with schizophrenia on a battery of tasks designed to probe voluntary averaging in different visual domains. Twenty-three outpatients with schizophrenia (mean age: 40±8 years; 3 female) and 20 age-matched control participants (mean age 39±9 years; 3 female) performed a motion coherence task and three equivalent noise (averaging) tasks, the latter allowing independent quantification of local and global limits on visual processing of motion, orientation and size. All performance measures were indistinguishable between the two groups (ps>0.05, one-way ANCOVAs), with one exception: participants with schizophrenia pooled fewer estimates of local orientation than controls when estimating average orientation (p = 0.01, one-way ANCOVA). These data do not support the notion of a generalised visual integration deficit in schizophrenia. Instead, they suggest that distinct visual dimensions are differentially affected in schizophrenia, with a specific impairment in the integration of visual orientation information.

Impaired recognition of communicative interactions from biological motion in schizophrenia

BACKGROUND

Patients with schizophrenia are deficient in multiple aspects of social cognition, including biological motion perception. In the present study we investigated the ability to read social information from point-light stimuli in schizophrenia.

METHODOLOGY/PRINCIPAL FINDINGS

Participants with paranoid schizophrenia and healthy controls were presented with a biological motion task depicting point-light actions of two agents either engaged in a communicative interaction, or acting independently of each other. For each stimulus, participants were asked to decide whether the two agents were communicating vs. acting independently of each other (task A), and to select the correct action description among five response alternatives (task B). Participants were also presented with a mental rotation task to assess their visuospatial abilities, and with a facial emotion recognition task tapping social cognition. Results revealed that participants with schizophrenia performed overall worse than controls both in discriminating communicative from non-communicative actions (task A) and in selecting which of the 5 response alternatives best described the observed actions (task B). Interestingly, the impaired performance of schizophrenic participants was mainly due to misclassification of non-communicative stimuli as communicative actions. Correlation analysis revealed that visuospatial abilities predicted performance in task A but not in task B, while facial emotion recognition abilities was correlated with performance in both task A and task B.

CONCLUSIONS/SIGNIFICANCE

These findings are consistent with theories of "overmentalizing" (excessive attribution of intentionality) in schizophrenia, and suggest that processing social information from biological motion does rely on social cognition abilities.

The neurophysiology of biological motion perception in schizophrenia

INTRODUCTION

The ability to recognize human biological motion is a fundamental aspect of social cognition that is impaired in people with schizophrenia. However, little is known about the neural substrates of impaired biological motion perception in schizophrenia. In the current study, we assessed event-related potentials (ERPs) to human and nonhuman movement in schizophrenia.

METHODS

Twenty-four subjects with schizophrenia and 18 healthy controls completed a biological motion task while their electroencephalography (EEG) was simultaneously recorded. Subjects watched clips of point-light animations containing 100%, 85%, or 70% biological motion, and were asked to decide whether the clip resembled human or nonhuman movement. Three ERPs were examined: P1, N1, and the late positive potential (LPP).

RESULTS

Behaviorally, schizophrenia subjects identified significantly fewer stimuli as human movement compared to healthy controls in the 100% and 85% conditions. At the neural level, P1 was reduced in the schizophrenia group but did not differ among conditions in either group. There were no group differences in N1 but both groups had the largest N1 in the 70% condition. There was a condition × group interaction for the LPP: Healthy controls had a larger LPP to 100% versus 85% and 70% biological motion; there was no difference among conditions in schizophrenia subjects.

CONCLUSIONS

Consistent with previous findings, schizophrenia subjects were impaired in their ability to recognize biological motion. The EEG results showed that biological motion did not influence the earliest stage of visual processing (P1). Although schizophrenia subjects showed the same pattern of N1 results relative to healthy controls, they were impaired at a later stage (LPP), reflecting a dysfunction in the identification of human form in biological versus nonbiological motion stimuli.

Absent activation in medial prefrontal cortex and temporoparietal junction but not superior temporal sulcus during the perception of biological motion in schizophrenia: a functional MRI study

BACKGROUND

Patients with schizophrenia show disturbances in both visual perception and social cognition. Perception of biological motion (BM) is a higher-level visual process, and is known to be associated with social cognition. BM induces activation in the "social brain network", including the superior temporal sulcus (STS). Although deficits in the detection of BM and atypical activation in the STS have been reported in patients with schizophrenia, it remains unclear whether other nodes of the "social brain network" are also atypical in patients with schizophrenia.

PURPOSE

We aimed to explore whether brain regions other than STS were involved during BM perception in patients with schizophrenia, using functional magnetic resonance imaging (fMRI).

METHODS AND PATIENTS

Seventeen patients with schizophrenia, and 17 age- and sex- matched healthy controls, underwent fMRI scanning during a one-back visual task, containing three experimental conditions: (1) BM, (2) scrambled motion (SM), and (3) static condition. We used one-sample t-tests to examine neural responses selective to BM versus SM within each group, and two-sample t-tests to directly compare neural patterns to BM versus SM in schizophrenics versus controls.

RESULTS

We found significant activation in the STS region when BM was contrasted with SM in both groups, with no significant difference between groups. On the contrary, significant activation in the medial prefrontal cortex (MPFC) and bilateral temporoparietal junction (TPJ) was found only in the control group. When we directly compared the two groups, the healthy controls showed significant greater activation in left MPFC and TPJ to BM versus SM than patients with schizophrenia.

CONCLUSION

Our findings suggest that patients with schizophrenia show normal activation to biologically and socially relevant motion stimuli in the STS, but atypical activation in other regions of the social brain network, specifically MPFC and TPJ. Moreover, these results were not due to atypical processing of motion, suggesting that patients with schizophrenia lack in the recruitment of neural circuits needed for the visual perception of social cognition.

Visual processing and social cognition in schizophrenia: relationships among eye movements, biological motion perception, and empathy

Schizophrenia patients have impairments at several levels of cognition including visual attention (eye movements), perception, and social cognition. However, it remains unclear how lower-level cognitive deficits influence higher-level cognition. To elucidate the hierarchical path linking deficient cognitions, we focused on biological motion perception, which is involved in both the early stage of visual perception (attention) and higher social cognition, and is impaired in schizophrenia. Seventeen schizophrenia patients and 18 healthy controls participated in the study. Using point-light walker stimuli, we examined eye movements during biological motion perception in schizophrenia. We assessed relationships among eye movements, biological motion perception and empathy. In the biological motion detection task, schizophrenia patients showed lower accuracy and fixated longer than healthy controls. As opposed to controls, patients exhibiting longer fixation durations and fewer numbers of fixations demonstrated higher accuracy. Additionally, in the patient group, the correlations between accuracy and affective empathy index and between eye movement index and affective empathy index were significant. The altered gaze patterns in patients indicate that top-down attention compensates for impaired bottom-up attention. Furthermore, aberrant eye movements might lead to deficits in biological motion perception and finally link to social cognitive impairments. The current findings merit further investigation for understanding the mechanism of social cognitive training and its development.

Deficient local biological motion perception in migraineurs: results from a duration discrimination paradigm

Migraine ranks as the third most common disease in the world and has caused significant losses of daily life abilities. Previously, people gave more attention to the pain of migraines and usually ignored the impairments of cognitive function in migraineurs. In the present study, a duration discrimination paradigm was used to assess the global and local biological motion perception in migraineurs and healthy controls. In the experiment, biological motion sequences and inanimate motion sequences (the inverted biological motion sequences) were sequentially presented on a screen. Observers were instructed to make a two-alternative forced choice to accurately indicate which interval (the first or the second) appeared longer. The stimuli involved global biological motion sequences and local biological motion sequences. The statistical analyses were conducted on the points of subjective equality that were obtained by fitting a psychometric function to each individual observer's data. In migraineurs, global biological motion signals lengthened the perceived temporal duration (as occurs in normal people), whereas local biological motion signals did not have this temporal dilation effect. The results indicated that patients with migraine showed a deficit in local biological motion perception, whereas their global biological motion perception was comparable to that of healthy subjects.

Sex Differences in the Neuromagnetic Cortical Response to Biological Motion

Body motion is a rich source of information for social interaction, and visual biological motion processing may be considered as a hallmark of social cognition. It is unclear, however, whether the social brain is sex specific. Here we assess sex impact on the magnetoencephalographic (MEG) cortical response to point-light human locomotion. Sex differences in the cortical MEG response to biological motion occur mostly over the right brain hemisphere. At early latencies, females exhibit a greater activation than males over the right parietal, left temporal, and right temporal cortex, a core of the social brain. At later latencies, the boosts of activation are greater in males over the right frontal and occipital cortices. The findings deliver the first evidence for gender-dependent modes in the time course and topography of the neural circuitry underpinning visual processing of biological motion. The outcome represents a framework for studying sex differences in the social brain in psychiatric and neurodevelopmental disorders.

Effects of domain-specific noise on visual motion processing in schizophrenia

Background

Visual perception impairments in schizophrenia stem from abnormal information processing. Information processing requires neural response to a stimulus (signal) against a backdrop of 1) random variation in baseline neural activity (internal noise) and sometimes irrelevant environmental stimulation (external noise). Filtering out noise is a critical aspect of information processing, and needs to be critically examined in schizophrenia.

Methods

To understand how noise in the visual system constrains perceptual processing, we devised a novel paradigm to build in both signal and external noise on same visual stimulus. Here, instead of uniformed noise, domain-specific noise—variations in stimulus speed—was introduced to evaluate the performance of schizophrenia patients in speed discrimination. Each motion stimulus—a random dot pattern (RDP) comprising 200 moving dots—included a range of speeds, drawn individually from a Gaussian distribution for each dot. The task for patients (n = 26) and controls (n = 28) was to identify which of two stimuli moved faster based on their mean speeds.

Findings

Patients exhibited deficient speed discrimination at baseline, in the absence of speed noise. Their speed discrimination was further degraded in the presence of low and medium levels of external noise. In the presence of a high levels of noise, degradation of patients' speed discrimination leveled-off, resulting in similar performance to controls.

Conclusion

These domain-specific noise effects on speed discrimination provide direct evidence for the existence of heightened internal noise within a specific visual motion processing domain in schizophrenia.