Emotion recognition and visual-scan paths in Fragile X syndrome

Adaptive group behavior of Fragile X mice in unfamiliar environments

Fragile X Syndrome (FXS) stands out as a prominent cause of inherited intellectual disability and a prevalent disorder closely linked to autism. FXS is characterized by substantial alterations in social behavior, encompassing social withdrawal, avoidance of eye contact, heightened social anxiety, increased arousal levels, language deficits, and challenges in regulating emotions. Conventional behavioral assessments primarily focus on short-term interactions within controlled settings. In this study, we conducted a comprehensive examination of the adaptive group behavior of Fmr1 KO male mice over a three-day period, without introducing experimental interventions or task-based evaluations. The data unveiled intricate behavioral anomalies, with the most significant changes manifesting during the initial adaptation to unfamiliar environments. Notably, certain behaviors exhibited a gradual return to typical patterns over time. This dynamic Fmr1 KO phenotype exhibited heightened activity, featuring increased exploration, amplified social interest, and an unconventional approach to social interactions characterized by a higher frequency of shorter engagements. These findings contribute to the growing understanding of social behavior in individuals with FXS and underscore the significance of comprehending their adaptive responses in various environmental contexts.

The use of eye-tracking technology as a tool to evaluate social cognition in people with an intellectual disability: a systematic review and meta-analysis

BACKGROUND

Relatively little is known about social cognition in people with intellectual disability (ID), and how this may support understanding of co-occurring autism. A limitation of previous research is that traditional social-cognitive tasks place a demand on domain-general cognition and language abilities. These tasks are not suitable for people with ID and lack the sensitivity to detect subtle social-cognitive processes. In autism research, eye-tracking technology has offered an effective method of evaluating social cognition-indicating associations between visual social attention and autism characteristics. The present systematic review synthesised research which has used eye-tracking technology to study social cognition in ID. A meta-analysis was used to explore whether visual attention on socially salient regions (SSRs) of stimuli during these tasks correlated with degree of autism characteristics presented on clinical assessment tools.

METHOD

Searches were conducted using four databases, research mailing lists, and citation tracking. Following in-depth screening and exclusion of studies with low methodological quality, 49 articles were included in the review. A correlational meta-analysis was run on Pearson's r values obtained from twelve studies, reporting the relationship between visual attention on SSRs and autism characteristics.

RESULTS AND CONCLUSIONS

Eye-tracking technology was used to measure different social-cognitive abilities across a range of syndromic and non-syndromic ID groups. Restricted scan paths and eye-region avoidance appeared to impact people's ability to make explicit inferences about mental states and social cues. Readiness to attend to social stimuli also varied depending on social content and degree of familiarity. A meta-analysis using a random effects model revealed a significant negative correlation (r = -.28, [95% CI -.47, -.08]) between visual attention on SSRs and autism characteristics across ID groups. Together, these findings highlight how eye-tracking can be used as an accessible tool to measure more subtle social-cognitive processes, which appear to reflect variability in observable behaviour. Further research is needed to be able to explore additional covariates (e.g. ID severity, ADHD, anxiety) which may be related to visual attention on SSRs, to different degrees within syndromic and non-syndromic ID groups, in order to determine the specificity of the association with autism characteristics.

Facial expression-based indicators of schizophrenia: Evidence from recent research

Impaired ability to recognize emotion in other's face (decoding) or to express emotion through the face (encoding) are considered critical in schizophrenia. The topic of research draws considerable attention since clinicians rely heavily on the patient's facial expressions for diagnosis and on the patient's ability to understand the clinician's communicative intent. While most researchers argue in favor of a generalized emotion deficit, others indicate an emotion-specific deficit in schizophrenia. An early review (Mandal et al., 1998) indicated a possible breakdown in perception-expression-experience link of emotion; later reviews (Kohler et al., 2010; Chan et al., 2010) pointed to a generalized emotion processing deficit due to perceptual deficits in schizophrenia. The present review (2010-2022) revisits this controversy with 47 published studies (37 decoding, 10 encoding) conducted on 2364 patients in 20 countries. Schizophrenia is characterized by reduced emotion processing ability, especially with negative symptoms and at an acute state of illness. It is however still unclear whether this dysfunction is independent of a generalized face perception deficit or of subjective experience of emotion in schizophrenia.

Electroretinography and contrast sensitivity, complementary translational biomarkers of sensory deficits in the visual system of individuals with fragile X syndrome

BACKGROUND

Disturbances in sensory function are an important clinical feature of neurodevelopmental disorders such as fragile X syndrome (FXS). Evidence also directly connects sensory abnormalities with the clinical expression of behavioral impairments in individuals with FXS; thus, positioning sensory function as a potential clinical target for the development of new therapeutics. Using electroretinography (ERG) and contrast sensitivity (CS), we previously reported the presence of sensory deficits in the visual system of the Fmr1-/y genetic mouse model of FXS. The goals of the current study were two-folds: (1) to assess the feasibility of measuring ERG and CS as a biomarker of sensory deficits in individuals with FXS, and (2) to investigate whether the deficits revealed by ERG and CS in Fmr1-/y mice translate to humans with FXS.

METHODS

Both ERG and CS were measured in a cohort of male individuals with FXS (n = 20, 18-45 years) and age-matched healthy controls (n = 20, 18-45 years). Under light-adapted conditions, and using both single flash and flicker (repeated train of flashes) stimulation protocols, retinal function was recorded from individual subjects using a portable, handheld, full-field flash ERG device (RETeval®, LKC Technologies Inc., Gaithersburg, MD, USA). CS was assessed in each subject using the LEA SYMBOLS® low-contrast test (Good-Lite, Elgin, IL, USA).

RESULTS

Data recording was successfully completed for ERG and assessment of CS in most individuals from both cohorts demonstrating the feasibility of these methods for use in the FXS population. Similar to previously reported findings from the Fmr1-/y genetic mouse model, individuals with FXS were found to exhibit reduced b-wave and flicker amplitude in ERG and an impaired ability to discriminate contrasts compared to healthy controls.

CONCLUSIONS

This study demonstrates the feasibility of using ERG and CS for assessing visual deficits in FXS and establishes the translational validity of the Fmr1-/y mice phenotype to individuals with FXS. By including electrophysiological and functional readouts, the results of this study suggest the utility of both ERG and CS (ERG-CS) as complementary translational biomarkers for characterizing sensory abnormalities found in FXS, with potential applications to the clinical development of novel therapeutics that target sensory function abnormalities to treat core symptomatology in FXS.

TRIAL REGISTRATION

ID-RCB number 2019-A01015-52 registered on the 17 May 2019.

Visual Behavior Impairments as an Aberrant Sensory Processing in the Mouse Model of Fragile X Syndrome

Fragile X Syndrome (FXS), the most common inherited form of human intellectual disability (ID) associated with autistic-like behaviors, is characterized by dys-sensitivity to sensory stimuli, especially vision. In the absence of Fragile Mental Retardation Protein (FMRP), both retinal and cerebral structures of the visual pathway are impaired, suggesting that perception and integration of visual stimuli are altered. However, behavioral consequences of these defects remain unknown. In this study, we used male Fmr1^−/y mice to further define visual disturbances from a behavioral perspective by focusing on three traits characterizing visual modality: perception of depth, contrasts and movements. We performed specific tests (Optomotor Drum, Visual Cliff) to evaluate these visual modalities, their evolution from youth to adulthood, and to assess their involvement in a cognitive task. We show that Fmr1^−/y mice exhibit alteration in their visual skills, displaying impaired perspective perception, a drop in their ability to understand a moving contrasted pattern, and a defect in contrasts discrimination. Interestingly, Fmr1^−/y phenotypes remain stable over time from adolescence to late adulthood. Besides, we report that color and shape are meaningful for the achievement of a cognitive test involving object recognition. Altogether, these results underline the significance of visual behavior alterations in FXS conditions and relevance of assessing visual skills in neuropsychiatric models before performing behavioral tasks, such as cognitive assessments, that involve visual discrimination.

Overview of Social Cognitive Dysfunctions in Rare Developmental Syndromes With Psychiatric Phenotype

Rare neurodevelopmental syndromes often present social cognitive deficits that may underlie difficulties in social interactions and increase the risk of psychosis or autism spectrum disorders. However, little is known regarding the specificities of social cognitive impairment across syndromes while it remains a major challenge for the care. Our review provides an overview of social cognitive dysfunctions in rare diseases associated with psychiatric symptoms (with a prevalence estimated between 1 in 1,200 and 1 in 25,000 live births: 22q11.2 deletion syndrome, Angelman syndrome, Fragile X syndrome, Klinefelter syndrome, Prader-Willi syndrome, Rett syndrome, Smith-Magenis syndrome, Turner syndrome, and Williams syndrome) and shed some light on the specific mechanisms that may underlie these skills in each clinical presentation. We first detail the different processes included in the generic expression "social cognition" before summarizing the genotype, psychiatric phenotype, and non-social cognitive profile in each syndrome. Then, we offer a systematic review of the social cognitive abilities and the disturbed mechanisms they are likely associated with. We followed the PRISMA process, including the definition of the relevant search terms, the selection of studies based on clear inclusion, and exclusion criteria and the quality appraisal of papers. We finally provide insights that may have considerable influence on the development of adapted therapeutic interventions such as social cognitive training (SCT) therapies specifically designed to target the psychiatric phenotype. The results of this review suggest that social cognition impairments share some similarities across syndromes. We propose that social cognitive impairments are strongly involved in behavioral symptoms regardless of the overall cognitive level measured by intelligence quotient. Better understanding the mechanisms underlying impaired social cognition may lead to adapt therapeutic interventions. The studies targeting social cognition processes offer new thoughts about the development of specific cognitive training programs, as they highlight the importance of connecting neurocognitive and SCT techniques.

Differential effects of anxiety and autism on social scene scanning in males with fragile X syndrome

BACKGROUND

Existing literature draws links between social attention and socio-behavioural profiles in neurodevelopmental disorders. Fragile X syndrome (FXS) is associated with a known socio-behavioural phenotype of social anxiety and social communication difficulties alongside high social motivation. However, studies investigating social attention in males with FXS are scarce. Using eye tracking, this study investigates social attention and its relationship with both anxiety and autism symptomatology in males with FXS.

METHODS

We compared dwell times to the background, body, and face regions of naturalistic social scenes in 11 males with FXS (M age = 26.29) and 11 typically developing (TD) children who were matched on gender and receptive language ability (M age = 6.28). Using informant-report measures, we then investigated the relationships between social scene scanning and anxiety, and social scene scanning and social communicative impairments.

RESULTS

Males with FXS did not differ to TD children on overall dwell time to the background, body, or face regions of the naturalistic social scenes. Whilst males with FXS displayed developmentally 'typical' social attention, increased looking at faces was associated with both heightened anxiety and fewer social communication impairments in this group.

CONCLUSIONS

These results offer novel insights into the mechanisms associated with social attention in FXS and provide evidence to suggest that anxiety and autism symptomatology, which are both heightened in FXS, have differential effects on social attention.

Visual preference for social stimuli in individuals with autism or neurodevelopmental disorders: an eye-tracking study

BACKGROUND

Recent research has identified differences in relative attention to competing social versus non-social video stimuli in individuals with autism spectrum disorder (ASD). Whether attentional allocation is influenced by the potential threat of stimuli has yet to be investigated. This is manipulated in the current study by the extent to which the stimuli are moving towards or moving past the viewer. Furthermore, little is known about whether such differences exist across other neurodevelopmental disorders. This study aims to determine if adolescents with ASD demonstrate differences in attentional allocation to competing pairs of social and non-social video stimuli, where the actor or object either moves towards or moves past the viewer, in comparison to individuals without ASD, and to determine if individuals with three genetic syndromes associated with differing social phenotypes demonstrate differences in attentional allocation to the same stimuli.

METHODS

In study 1, adolescents with ASD and control participants were presented with social and non-social video stimuli in two formats (moving towards or moving past the viewer) whilst their eye movements were recorded. This paradigm was then employed with groups of individuals with fragile X, Cornelia de Lange, and Rubinstein-Taybi syndromes who were matched with one another on chronological age, global adaptive behaviour, and verbal adaptive behaviour (study 2).

RESULTS

Adolescents with ASD demonstrated reduced looking-time to social versus non-social videos only when stimuli were moving towards them. Individuals in the three genetic syndrome groups showed similar looking-time but differences in fixation latency for social stimuli moving towards them. Across both studies, we observed within- and between-group differences in attention to social stimuli that were moving towards versus moving past the viewer.

CONCLUSIONS

Taken together, these results provide strong evidence to suggest differential visual attention to competing social versus non-social video stimuli in populations with clinically relevant, genetically mediated differences in socio-behavioural phenotypes.

Quantifying naturalistic social gaze in fragile X syndrome using a novel eye tracking paradigm

A hallmark behavioral feature of fragile X syndrome (FXS) is the propensity for individuals with the syndrome to exhibit significant impairments in social gaze during interactions with others. However, previous studies employing eye tracking methodology to investigate this phenomenon have been limited to presenting static photographs or videos of social interactions rather than employing a real-life social partner. To improve upon previous studies, we used a customized eye tracking configuration to quantify the social gaze of 51 individuals with FXS and 19 controls, aged 14-28 years, while they engaged in a naturalistic face-to-face social interaction with a female experimenter. Importantly, our control group was matched to the FXS group on age, developmental functioning, and degree of autistic symptomatology. Results showed that participants with FXS spent significantly less time looking at the face and had shorter episodes (and longer inter-episodes) of social gaze than controls. Regression analyses indicated that communication ability predicted higher levels of social gaze in individuals with FXS, but not in controls. Conversely, degree of autistic symptoms predicted lower levels of social gaze in controls, but not in individuals with FXS. Taken together, these data indicate that naturalistic social gaze in FXS can be measured objectively using existing eye tracking technology during face-to-face social interactions. Given that impairments in social gaze were specific to FXS, this paradigm could be employed as an objective and ecologically valid outcome measure in ongoing Phase II/Phase III clinical trials of FXS-specific interventions.

Implicit Discrimination of Basic Facial Expressions of Positive/Negative Emotion in Fragile X Syndrome and Autism Spectrum Disorder

Fragile X syndrome (FXS) and autism spectrum disorders (ASD) are characterized by impaired social functioning. We examined the spontaneous discrimination of happy and disgusted facial expressions, from neutral faces, in individuals with FXS (n  =  13, Mage  =  19.70) and ASD (n  =  15, Mage  =  11.00) matched on adaptive behavior and verbal abilities measured by the Vineland Adaptive Behavior Scale. Eye gaze to the eyes and mouth of neutral faces was also measured. Results suggest individuals with FXS and ASD distinguish facial expressions spontaneously in the same way. Individuals with FXS looked significantly less at the eye region of neutral faces than individuals with ASD. These results provide insight into similarities and differences in face processing in two neurodevelopmental disorders noted for their similarities in social behavior.

Effects of labeling and pointing on object gaze in boys with fragile X syndrome: an eye-tracking study

We examined the visual processing of a social learning stimulus and the ways in which visual attention was distributed to objects as well as to the examiner's face during word learning under conditions that varied only in the presence or absence of a label. The goal of the current study, then, was to evaluate the effects of differentially providing pointing and labeling during exposure to a novel target object in males with fragile X syndrome (FXS) (n=14, ages 4.33-10.02), autism spectrum disorder (ASD) (n=17, ages 4.04-10.4), or typical development (TD) (n=18, ages 2.05-5.33). In particular, the present study examined attention to the examiner's face as well as target and distracter objects that were presented as video stimuli. An eye-tracker captured gaze to the video stimuli as they were shown in order to examine the way in which children with FXS, ASD, or TD distributed their gaze toward the examiner and the objects. Results indicated that no group showed increased gaze toward the target object compared to the distracter object. However, results revealed that participants with FXS showed significantly increased face gaze compared to the novel objects, whereas children with ASD and TD both showed similar amounts of relative gaze toward the face and objects. Furthermore, the act of pointing at the target object was found to increase gaze toward the target objects compared to when there was no pointing in all groups. Together, these findings suggest that social cues like those employed in a word-learning task, when presented with video, may relate to gaze in FXS in context- or task-dependent ways that are distinct from those expected during live interaction.

The contribution of inhibitory interneurons to circuit dysfunction in Fragile X Syndrome

Many neurological disorders, including neurodevelopmental disorders, report hypersynchrony of neuronal networks. These alterations in neuronal synchronization suggest a link to the function of inhibitory interneurons. In Fragile X Syndrome (FXS), it has been reported that altered synchronization may underlie hyperexcitability, cognitive dysfunction and provide a link to the increased incidence of epileptic seizures. Therefore, understanding the roles of inhibitory interneurons and how they control neuronal networks is of great importance in studying neurodevelopmental disorders such as FXS. Here, we present a review of how interneuron populations and inhibition are important contributors to the loss of excitatory/inhibitory balance seen in hypersynchronous and hyperexcitable networks from neurodevelopmental disorders, and specifically in FXS.

Social approach and emotion recognition in fragile X syndrome

Evidence is emerging that individuals with Fragile X syndrome (FXS) display emotion recognition deficits, which may contribute to their significant social difficulties. The current study investigated the emotion recognition abilities, and social approachability judgments, of FXS individuals when processing emotional stimuli. Relative to chronological age- (CA-) and mental age- (MA-) matched controls, the FXS group performed significantly more poorly on the emotion recognition tasks, and displayed a bias towards detecting negative emotions. Moreover, after controlling for emotion recognition deficits, the FXS group displayed significantly reduced ratings of social approachability. These findings suggest that a social anxiety pattern, rather than poor socioemotional processing, may best explain the social avoidance observed in FXS.

Viewing social scenes: a visual scan-path study comparing fragile X syndrome and Williams syndrome

Fragile X syndrome (FXS) and Williams syndrome (WS) are both genetic disorders which present with similar cognitive-behavioral problems, but distinct social phenotypes. Despite these social differences both syndromes display poor social relations which may result from abnormal social processing. This study aimed to manipulate the location of socially salient information within scenes to investigate the visual attentional mechanisms of: capture, disengagement, and/or general engagement. Findings revealed that individuals with FXS avoid social information presented centrally, at least initially. The WS findings, on the other hand, provided some evidence that difficulties with attentional disengagement, rather than attentional capture, may play a role in the WS social phenotype. These findings are discussed in relation to the distinct social phenotypes of these two disorders.

Hyper-reactivity in fragile X syndrome females: generalised or specific to socially-salient stimuli? A skin conductance study

Fragile X syndrome (FXS) is characterised by hyper-reactivity, autistic tendencies and social anxiety. It has been hypothesised that the FXS social phenotype is secondary to a generalised hyper-reactivity that leads to social avoidance. No study, however, has investigated whether hyperarousal in FXS is generalised or more specific to socially salient information. We recorded skin conductance responses (SCRs) while females with FXS, as well as chronological age-(CA-) and mental age-(MA-) matched controls, viewed two sets of visual images: direct-gaze emotional faces and affectively arousing scenes. Explicit emotion recognition and subjective ratings of emotions aroused by images were also recorded. Overall, females with FXS displayed hyper-reactivity only when viewing the more socially salient stimuli (emotional faces), compared to CA-matched controls, but not MA-matched controls. Moreover, females with FXS also displayed atypical emotion recognition abilities and subjective ratings of their own emotional states. These findings suggest that any hyper-reactivity observed in FXS may be more specific to socially salient stimuli, rather than generalised.