Neurophysiological correlates of holistic face processing in adolescents with and without autism spectrum disorder

Autistic traits specific to communication ability are associated with performance on a Mooney face detection task

Difficulties in global face processing have been associated with autism. However, autism is heterogenous, and it is not known which dimensions of autistic traits are implicated in face-processing difficulties. To address this gap in knowledge, we conducted two experiments to examine how identification of Mooney face stimuli (stylized, black-and-white images of faces without details) related to the six subscales of the Comprehensive Autistic Trait Inventory in young adults. In Experiment 1, regression analyses indicated that participants with poorer communication skills had lower task sensitivity when discriminating between face-present and face-absent images, whilst other autistic traits had no unique predictive value. Experiment 2 replicated these findings and additionally showed that autistic traits were linked to a reduced face inversion effect. Taken together, these results indicate autistic traits, especially communication difficulties, are associated with reduced configural processing of face stimuli. It follows that both reduced sensitivity for identifying upright faces amongst similar-looking distractors and reduced susceptibility to face inversion effects may be linked to relatively decreased reliance on configural processing of faces in autism. This study also reinforces the need to consider the different facets of autism independently.

Investigating the Face Inversion Effect in Autism Across Behavioral and Neural Measures of Face Processing: A Systematic Review and Bayesian Meta-Analysis

Importance

Face processing is foundational to human social cognition, is central to the hallmark features of autism spectrum disorder (ASD), and shapes neural systems and social behavior. Highly efficient and specialized, the face processing system is sensitive to inversion, demonstrated by reduced accuracy in recognition and altered neural response to inverted faces. Understanding at which mechanistic level the autistic face processing system may be particularly different, as measured by the face inversion effect, will improve overall understanding of brain functioning in autism.

Objective

To synthesize data from the extant literature to determine differences of the face processing system in ASD, as measured by the face inversion effect, across multiple mechanistic levels.

Data Sources

Systematic searches were conducted in the MEDLINE, Embase, Web of Science, and PubMed databases from inception to August 11, 2022.

Study Selection

Original research that reported performance-based measures of face recognition to upright and inverted faces in ASD and neurotypical samples were included for quantitative synthesis. All studies were screened by at least 2 reviewers.

Data Extraction and Synthesis

This systematic review and meta-analysis was conducted according to the 2020 Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline. Multiple effect sizes were extracted from studies to maximize information gain and statistical precision and used a random-effects, multilevel modeling framework to account for statistical dependencies within study samples.

Main Outcomes and Measures

Effect sizes were calculated as a standardized mean change score between ASD and neurotypical samples (ie, Hedges g). The primary outcome measure was performance difference between upright and inverted faces during face recognition tasks. Measurement modality, psychological construct, recognition demand, sample age, sample sex distribution, and study quality assessment scores were assessed as moderators.

Results

Of 1768 screened articles, 122 effect sizes from 38 empirical articles representing data from 1764 individual participants (899 ASD individuals and 865 neurotypical individuals) were included in the meta-analysis. Overall, face recognition performance differences between upright and inverted faces were reduced in autistic individuals compared with neurotypical individuals (g = -0.41; SE = 0.11; 95% credible interval [CrI], -0.63 to -0.18). However, there was considerable heterogeneity among effect sizes, which were explored with moderator analysis. The attenuated face inversion effect in autistic individuals was more prominent in emotion compared with identity recognition (b = 0.46; SE = 0.26; 95% CrI, -0.08 to 0.95) and in behavioral compared with electrophysiological measures (b = 0.23; SE = 0.24; 95% CrI, -0.25 to 0.70).

Conclusions and Relevance

This study found that on average, face recognition in autism is less impacted by inversion. These findings suggest less specialization or expertise of the face processing system in autism, particularly in recognizing emotion from faces as measured in behavioral paradigms.

A randomized cross-over trial investigating the neurocognitive effects of acute exercise on face recognition in children with autism spectrum disorder

Difficulties in face recognition contribute to social-cognitive problems in autistic children. Evidence on behavioral interventions targeting this cognitive domain is limited. In non-autistic individuals, a single exercise session is known to elicit temporary benefits for several cognitive functions. Our study investigates whether acute aerobic exercise influences face recognition in autistic children. In a randomized order, 29 participants completed a 20-min moderately-intense cycling bout on an ergometer and a control condition. Before and after each condition, participants categorized Mooney faces and instruments during a computerized cognitive task. Simultaneously, the N170 component of event-related potentials and pupil size were recorded using electroencephalography and eyetracking, respectively. As indicated by a greater increase of reaction time in the exercise compared to the control condition, the results revealed impaired face recognition following aerobic exercise. This effect was accompanied by a lower decrease of the positive N170 amplitude and a trend towards a greater constriction of the pupil size in the exercise compared to the control condition. Our findings highlight the interplay of the physiological state and face recognition in autistic children. Exercise-induced impairments in this social-cognitive ability may be due to an interference with the learning effect that is typically seen for the structural encoding of faces.

Inferential Emotion Tracking reveals impaired context-based emotion processing in individuals with high Autism Quotient scores

Emotion perception is essential for successful social interactions and maintaining long-term relationships with friends and family. Individuals with autism spectrum disorder (ASD) experience social communication deficits and have reported difficulties in facial expression recognition. However, emotion recognition depends on more than just processing face expression; context is critically important to correctly infer the emotions of others. Whether context-based emotion processing is impacted in those with Autism remains unclear. Here, we used a recently developed context-based emotion perception task, called Inferential Emotion Tracking (IET), and investigated whether individuals who scored high on the Autism Spectrum Quotient (AQ) had deficits in context-based emotion perception. Using 34 videos (including Hollywood movies, home videos, and documentaries), we tested 102 participants as they continuously tracked the affect (valence and arousal) of a blurred-out, invisible character. We found that individual differences in Autism Quotient scores were more strongly correlated with IET task accuracy than they are with traditional face emotion perception tasks. This correlation remained significant even when controlling for potential covarying factors, general intelligence, and performance on traditional face perception tasks. These findings suggest that individuals with ASD may have impaired perception of contextual information, it reveals the importance of developing ecologically relevant emotion perception tasks in order to better assess and treat ASD, and it provides a new direction for further research on context-based emotion perception deficits in ASD.

Atypical oscillatory dynamics during emotional face processing in paediatric obsessive-compulsive disorder with MEG

Children and youth with obsessive-compulsive disorder (OCD) demonstrate difficulties with social, emotional and cognitive functions in addition to the core diagnosis of obsessions and compulsions. This is the first magnetoencephalography (MEG) study to examine whole-brain neurophysiological functional connectivity of emotional face processing networks in paediatric OCD. Seventy-two participants (OCD: n = 36; age 8-17 yrs; typically developing controls: n = 36, age 8-17 yrs) completed an implicit emotional face processing task in the MEG. Functional connectivity networks in canonical frequency bands were compared between groups, and within OCD and control groups between emotions (angry vs. happy). Between groups, participants with OCD showed increased functional connectivity in the gamma band to angry faces, suggesting atypical perception of angry faces in OCD. Within groups, the OCD group showed greater engagement of the beta band, suggesting the over-use of top-down processing when perceiving happy versus angry emotions, while controls engaged in bottom-up gamma processing, also greater to happy faces. Over-activation of top-down processing has been linked to difficulties modifying one's cognitive set. Findings establish altered patterns of neurophysiological connectivity in children with OCD, and are striking in their oscillatory specificity. Our results contribute to a greater understanding of the neurobiology of the disorder, and are foundational for the possibility of alternative targets for intervention.

Qualitative differences in the spatiotemporal brain states supporting configural face processing emerge in adolescence in autism

BACKGROUND

Studying the neural processing of faces can illuminate the mechanisms of compromised social expertise in autism. To resolve a longstanding debate, we examined whether differences in configural face processing in autism are underpinned by quantitative differences in the activation of typical face processing pathways, or the recruitment of non-typical neural systems.

METHODS

We investigated spatial and temporal characteristics of event-related EEG responses to upright and inverted faces in a large sample of children, adolescents, and adults with and without autism. We examined topographic analyses of variance and global field power to identify group differences in the spatial and temporal response to face inversion. We then examined how quasi-stable spatiotemporal profiles - microstates - are modulated by face orientation and diagnostic group.

RESULTS

Upright and inverted faces produced distinct profiles of topography and strength in the topographical analyses. These topographical profiles differed between diagnostic groups in adolescents, but not in children or adults. In the microstate analysis, the autistic group showed differences in the activation strength of normative microstates during early-stage processing at all ages, suggesting consistent quantitative differences in the operation of typical processing pathways; qualitative differences in microstate topographies during late-stage processing became prominent in adults, suggesting the increasing involvement of non-typical neural systems with processing time and over development.

CONCLUSIONS

These findings suggest that early difficulties with configural face processing may trigger later compensatory processes in autism that emerge in later development.

Oxytocin impacts top-down and bottom-up social perception in adolescents with ASD: a MEG study of neural connectivity

Background

In the last decade, accumulative evidence has shown that oxytocin can modulate social perception in typically developed individuals and individuals diagnosed with autism. While several studies show that oxytocin (OT) modulates neural activation in social-related neural regions, the mechanism that underlies OT effects in ASD is not fully known yet. Despite evidence from animal studies on connections between the oxytocinergic system and excitation/inhibition neural balance, the influence of OT on oscillatory responses among individuals with ASD has been rarely examined. To bridge these gaps in knowledge, we investigated the effects of OT on both social and non-social stimuli while focusing on its specific influence on the neural connectivity between three socially related neural regions—the left and right fusiform and the medial frontal cortex.

Methods

Twenty-five adolescents with ASD participated in a wall-established social task during a randomized, double-blind placebo-controlled MEG and OT administration study. Our main task was a social-related task that required the identification of social and non-social-related pictures. We hypothesized that OT would modulate the oscillatory connectivity between three pre-selected regions of interest to be more adaptive to social processing. Specifically, we focused on alpha and gamma bands which are known to play an important role in face processing and top-down/bottom-up balance.

Results

Compared to placebo, OT reduced the connectivity between the medial frontal cortex and the fusiform in the low gamma more for social stimuli than for non-social ones, a reduction that was correlated with individuals’ performance in the task. Additionally, for both social and non-social stimuli, OT increased the connectivity in the alpha and beta bands.

Limitations

Sample size was determined based on sample sizes previously reported in MEG in clinical populations, especially OT administration studies in combination with neuroimaging in ASD. We were limited in our capability to recruit for such a study, and as such, the sample size was not based on a priori power analysis. Additionally, we limited our analyses to specific neural bands and regions. To validate the current results, future studies may be needed to explore other parameters using whole-brain approaches in larger samples.

Conclusion

These results suggest that OT influenced social perception by modifying the communication between frontal and posterior regions, an attenuation that potentially impacts both social and non-social early perception. We also show that OT influences differ between top-down and bottom-up processes, depending on the social context. Overall, by showing that OT influences both social-related perception and overall attention during early processing stages, we add new information to the existing understanding of the impact of OT on neural processing in ASD. Furthermore, by highlighting the influence of OT on early perception, we provide new directions for treatments for difficulties in early attentional phases in this population.

Trial registration Registered on October 27, 2021—Retrospectively registered, https://clinicaltrials.gov/ct2/show/record/NCT05096676 (details on clinical registration can be found in www.clinicalTrial.gov, unique identifier: NCT05096676).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13229-022-00513-6.

High-level visual search in children with autism

Visual search has been classified as easy feature search, with rapid target detection and little set size dependence, versus slower difficult search with focused attention, with set size–dependent speed. Reverse hierarchy theory attributes these classes to rapid high cortical-level vision at a glance versus low-level vision with scrutiny, attributing easy search to high-level representations. Accordingly, faces “pop out” of heterogeneous object photographs. Individuals with autism have difficulties recognizing faces, and we now asked if this disability disturbs their search for faces. We compare search times and set size slopes for children with autism spectrum disorders (ASDs) and those with neurotypical development (NT) when searching for faces. Human face targets were found rapidly, with shallow set size slopes. The between-group difference between slopes (18.8 vs. 11.3 ms/item) is significant, suggesting that faces may not “pop out” as easily, but in our view does not warrant classifying ASD face search as categorically different from that of NT children. We also tested search for different target categories, dog and lion faces, and nonface basic categories, cars and houses. The ASD group was generally a bit slower than the NT group, and their slopes were somewhat steeper. Nevertheless, the overall dependencies on target category were similar: human face search fastest, nonface categories slowest, and dog and lion faces in between. We conclude that autism may spare vision at a glance, including face detection, despite its reported effects on face recognition, which may require vision with scrutiny. This dichotomy is consistent with the two perceptual modes suggested by reverse hierarchy theory.

The “Primitive Brain Dysfunction” Theory of Autism: The Superior Colliculus Role

A better understanding of the pathogenesis of autism will help clarify our conception of the complexity of normal brain development. The crucial deficit may lie in the postnatal changes that vision produces in the brainstem nuclei during early life. The superior colliculus is the primary brainstem visual center. Although difficult to examine in humans with present techniques, it is known to support behaviors essential for every vertebrate to survive, such as the ability to pay attention to relevant stimuli and to produce automatic motor responses based on sensory input. From birth to death, it acts as a brain sentinel that influences basic aspects of our behavior. It is the main brainstem hub that lies between the environment and the rest of the higher neural system, making continuous, implicit decisions about where to direct our attention. The conserved cortex-like organization of the superior colliculus in all vertebrates allows the early appearance of primitive emotionally-related behaviors essential for survival. It contains first-line specialized neurons enabling the detection and tracking of faces and movements from birth. During development, it also sends the appropriate impulses to help shape brain areas necessary for social-communicative abilities. These abilities require the analysis of numerous variables, such as the simultaneous evaluation of incoming information sustained by separate brain networks (visual, auditory and sensory-motor, social, emotional, etc.), and predictive capabilities which compare present events to previous experiences and possible responses. These critical aspects of decision-making allow us to evaluate the impact that our response or behavior may provoke in others. The purpose of this review is to show that several enigmas about the complexity of autism might be explained by disruptions of collicular and brainstem functions. The results of two separate lines of investigation: 1. the cognitive, etiologic, and pathogenic aspects of autism on one hand, and two. the functional anatomy of the colliculus on the other, are considered in order to bridge the gap between basic brain science and clinical studies and to promote future research in this unexplored area.

Atypically slow processing of faces and non-faces in older autistic adults

Face recognition is a fundamental function that requires holistic processing. Differences in face processing have been consistently identified in autistic children, but it is unknown whether these differences persist across the adult lifespan. Using event-related functional magnetic resonance imaging, we measured holistic face processing with a rapid Mooney faces task in 50 autistic and 49 non-autistic participants (30–74 years). Behavioral tasks included a self-paced version of the same paradigm and a global–local processing task (Navon). Reduced detection rates for faces, but not non-faces, were found in autistic adults, including slower responses on all conditions. Without time constraints, differences in accuracy disappeared between groups, although reaction times in correctly identifying faces remained higher in autistic adults. The functional magnetic resonance imaging results showed lower activation in the left and right superior frontal gyrus in the autism group but no age-related differences. Overall, our findings point toward slower information processing speed rather than a face recognition deficit in autistic adults. This suggests that face-processing differences are not a core feature of autism across the adult lifespan.

Classification of evoked responses to inverted faces reveals both spatial and temporal cortical response abnormalities in Autism spectrum disorder

The neurophysiology of face processing has been studied extensively in the context of social impairments associated with autism spectrum disorder (ASD), but the existing studies have concentrated mainly on univariate analyses of responses to upright faces, and, less frequently, inverted faces. The small number of existing studies on neurophysiological responses to inverted face in ASD have used univariate approaches, with divergent results. Here, we used a data-driven, classification-based, multivariate machine learning decoding approach to investigate the temporal and spatial properties of the neurophysiological evoked response for upright and inverted faces, relative to the neurophysiological evoked response for houses, a neutral stimulus. 21 (2 females) ASD and 29 (4 females) TD participants ages 7 to 19 took part in this study. Group level classification accuracies were obtained for each condition, using first the temporal domain of the evoked responses, and then the spatial distribution of the evoked responses on the cortical surface, each separately. We found that classification of responses to inverted neutral faces vs. houses was less accurate in ASD compared to TD, in both the temporal and spatial domains. In contrast, there were no group differences in the classification of evoked responses to upright neutral faces relative to houses. Using the classification in the temporal domain, lower decoding accuracies in ASD were found around 120 ms and 170 ms, corresponding the known components of the evoked responses to faces. Using the classification in the spatial domain, lower decoding accuracies in ASD were found in the right superior marginal gyrus (SMG), intra-parietal sulcus (IPS) and posterior superior temporal sulcus (pSTS), but not in core face processing areas. Importantly, individual classification accuracies from both the temporal and spatial classifiers correlated with ASD severity, confirming the relevance of the results to the ASD phenotype.

The baby schema effect in adolescence and its difference from that in adulthood

The baby schema effect induced by particular features of baby faces acts as an innate releasing mechanism that evokes positive emotions and instinctual behavioral responses. Our prior research in adults has revealed that this effect initially found in infancy extends into child faces. Adolescence is an important period involving development in various aspects of cognition, including face perception. Here, we investigated whether the extended baby schema effect we previously found in adult observers develops earlier-in adolescence-and how different it appears in adolescents as compared with in adults. In the current study, 76 adolescents and 77 adults were asked to judge the likeability of 148 neutral faces of infants and children (0.08-6.5 years of age) on 7-point scales. Results showed that both adolescents and adults perceived the faces of both infants and children younger than 4.6 years as more likeable relative to those of older children, indicating that the baby schema effect previously found in adulthood also occurs in adolescence. However, adolescents rated lower than adults toward the infant and child faces across all face ages, suggesting that this effect might be under development in adolescence. Overall, our findings provide new evidence for the development of face perception in adolescence and demonstrate age-related changes in innate releasing mechanisms in our protective and caretaking responses toward infants and children.

Reduced neural sensitivity to rapid individual face discrimination in autism spectrum disorder

Background

Individuals with autism spectrum disorder (ASD) are characterized by impairments in social communication and interaction. Although difficulties at processing social signals from the face in ASD have been observed and emphasized for many years, there is a lot of inconsistency across both behavioral and neural studies.

Methods

We recorded scalp electroencephalography (EEG) in 23 8-to-12 year old boys with ASD and 23 matched typically developing boys using a fast periodic visual stimulation (FPVS) paradigm, providing objective (i.e., frequency-tagged), fast (i.e., few minutes) and highly sensitive measures of rapid face categorization, without requiring any explicit face processing task. We tested both the sensitivity to rapidly (i.e., at a glance) categorize faces among other objects and to individuate unfamiliar faces.

Outcomes

While general neural synchronization to the visual stimulation and neural responses indexing generic face categorization were undistinguishable between children with ASD and typically developing controls, neural responses indexing individual face discrimination over the occipito-temporal cortex were substantially reduced in the individuals with ASD. This difference vanished when faces were presented upside-down, due to the lack of significant face inversion effect in ASD.

Interpretation

These data provide original evidence for a selective high-level impairment in individual face discrimination in ASD in an implicit task. The objective and rapid assessment of this function opens new perspectives for ASD diagnosis in clinical settings.

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We assess implicit face processing in ASD via Fast Periodic Visual Stimulation EEG.

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Rapid categorization of a face as a face is not impaired in children with ASD.

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Individual face discrimination is selectively impaired in ASD.

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Children with ASD show no face inversion effect.

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FPVS-EEG opens new perspectives for clinical settings.