Rapid and objective assessment of neural function in autism spectrum disorder using transient visual evoked potentials

OBJECTIVE: There is a critical need to identify biomarkers and objective outcome measures that can be used to understand underlying neural mechanisms in autism spectrum disorder (ASD). Visual evoked potentials (VEPs) offer a noninvasive technique to evaluate the functional integrity of neural mechanisms, specifically visual pathways, while probing for disease pathophysiology. METHODS: Transient VEPs (tVEPs) were obtained from 96 unmedicated children, including 37 children with ASD, 36 typically developing (TD) children, and 23 unaffected siblings (SIBS). A conventional contrast-reversing checkerboard condition was compared to a novel short-duration condition, which was developed to enable objective data collection from severely affected populations who are often excluded from electroencephalographic (EEG) studies. RESULTS: Children with ASD showed significantly smaller amplitudes compared to TD children at two of the earliest critical VEP components, P60-N75 and N75-P100. SIBS showed intermediate responses relative to ASD and TD groups. There were no group differences in response latency. Frequency band analyses indicated significantly weaker responses for the ASD group in bands encompassing gamma-wave activity. Ninety-two percent of children with ASD were able to complete the short-duration condition compared to 68% for the standard condition. CONCLUSIONS: The current study establishes the utility of a short-duration tVEP test for use in children at varying levels of functioning and describes neural abnormalities in children with idiopathic ASD. Implications for excitatory/inhibitory balance as well as the potential application of VEP for use in clinical trials are discussed

Empathy for others' pain is disrupted at the neurophysiological level in schizophrenia.

OBJECTIVE: Previous research has shown that empathy for pain is disrupted at the neural level in people with schizophrenia. However, many of these studies have failed to assess key background contextual variables that have previously been linked to neurophysiological responding. Moreover, no study to date has examined the potential influence of schizotypal characteristics on neurophysiological responding in non-clinical individuals. METHODS: People with schizophrenia (N = 17) were compared to demographically matched controls (N = 19) on an event-related potential (ERP) empathy for pain paradigm. The control group also completed a measure of schizotypal personality traits. RESULTS: People with schizophrenia exhibited atypical neural responding at early, emotion-sharing (frontal N110), and late, cognitive (central late positive potential [LPP]) processing stages of pain empathy, relative to controls. In the control group, positive schizotypy traits were significantly negatively related to reduced ERP amplitude in the late, cognitive (central LPP) processing stage of empathy. CONCLUSIONS: These data cross-validate previous studies that have shown that schizophrenia is associated with atypicalities in bottom-up automatic resonance processes that likely contribute to empathic and socio-emotional processing deficits, and indicate that these findings cannot be easily attributed to background contextual differences between the two groups. The results also point to a potential relationship between positive schizotypal characteristics and neurophysiological responding. Implications for simulation theories of empathy and social functioning in schizophrenia are discussed. PRACTITIONER POINTS: Empathic processing has been consistently linked to well-being and mental health in many groups, including people with schizophrenia. Previous research has shown that, relative to controls, people with schizophrenia exhibit abnormalities in their neurophysiological empathic response, but in these prior studies, the two groups also differed in a number of potentially important background contextual variables. The current study shows that, when closely matched on background contextual variables, abnormal neural responding is still evident. These data suggest that empathy for pain is disrupted at the neurophysiological level in schizophrenia

A role for affectivity in rapid facial mimicry: An electromyographic study.

Emotional expressions evoke rapid facial reactions in the perceiver that are consistent with the valence of the observed expression. We aimed to investigate whether this robust facial reaction is purely a motor matching response or instead represents underlying affective processes. Participants' (N = 60) corrugator supercilii and zygomaticus major muscle activity was quantified using facial electromyography (EMG) while they viewed three sets of images; (i) upright happy and angry facial expressions, (ii) inverted happy and angry facial expressions, and (iii) sad and happy eyes and mouth expressions. Participants displayed patterns of EMG responding that were consistent with the affective valence of the emotional expression, as opposed to merely matching the observed stimuli (i.e. a motor matching response). Using a novel methodological approach, these findings provide evidence for the contention that affective processing underlies rapid facial mimicry reactions

Intact spontaneous emotional expressivity to non-facial but not facial stimuli in schizophrenia: An electromyographic study.

Emotional stimuli, such as facial expressions, reliably evoke rapid, spontaneous and covert facial reactions in the perceiver that reflect the affective valence of the observed stimulus. These physiological reactions have been linked to a variety of social cognitive processes known to be disrupted in schizophrenia, such as emotion recognition and affective empathy. Moreover, individuals with schizophrenia exhibit atypical rapid facial reactions when observing emotional expressions. The current study aimed to determine if the disruption in schizophrenia is specific to facial expressions, or instead reflects more generalised emotional or motor impairments in the elicitation of this rapid facial response. Here we quantified activity in the corrugator supercilii and zygomaticus major muscle regions using electromyography while individuals with schizophrenia (n = 24) and controls (n = 21) viewed images of facial and non-facial emotional stimuli. The results indicate that schizophrenia is marked by a disruption in rapid facial responding to facial expressions, but intact responding to non-facial emotional stimuli. This dissociation between the processing of facial and non-facial emotional stimuli points to the need for a greater understanding of the degree to which facial emotion processing impairments contribute to disruptions in mimetic responding in this population

Age invariance in rapid facial affective reactions to emotionally valenced stimuli.

It has been suggested that an age-related positivity effect may only occur in the context of explicit information processing, but it is unclear whether this bias extends to the processing of rapid facial reactions. In addition, most studies that have looked for evidence of age-related implicit positivity have used attentional (as opposed to sensory) unawareness paradigms, or used broad-based indicators of attentional awareness that do not speak to the nature of the affective response. In the present study, younger and older adults were therefore asked to view non-facial images presented supraliminally (i.e., consciously) as well as outside of sensory awareness (i.e., subliminally) while their facial reactions were indexed using electromyography. The results indicated that both younger and older adults exhibited rapid facial reactions congruent with the emotional valence of non-facial images in both supraliminal and subliminal conditions. Relative to young, older adults did not respond with greater zygomaticus (cheek) activity to positive stimuli or reduced corrugator (brow) activity to negative stimuli in either condition. These data show that rapid facial reactions to emotional stimuli are intact in late adulthood, even in response to stimuli that activate more automatic and implicit forms of emotion processing. However, there is no evidence for any age-related positivity bias in these behavioral responses

Continuity of temperament subgroup classifications from infancy to toddlerhood in the context of early autism traits

Our previous cross-sectional investigation (Chetcuti et al., 2020) showed that infants with autism traits could be divided into distinct subgroups based on temperament. This longitudinal study builds on this existing work by exploring the continuity of temperament subgroup classifications and their associations with behavioral/clinical phenotypic features from infancy to toddlerhood. 103 infants (68% male) showing early signs of autism were referred to the study by community healthcare professionals and seen for assessments when aged around 12-months (Time 1), 18-months (Time 2), and 24-months (Time 3). Latent profile analysis revealed inhibited/low positive, active/negative reactive, and sociable/well-regulated subgroups at each timepoint, and a unique reactive/regulated subgroup at Time 3. Cross-tabulations indicated a significant likelihood of children having a recurrent subgroup classification from one timepoint to the next, and no apparent patterns to the movement of children who did change from one subgroup to another over time. Temperament subgroups were associated with concurrent child social–emotional functioning and autism traits, but unrelated to child age, sex, or developmental level. These findings suggest that temperament subgroup classifications might represent a reliable and very early indicator of autism characteristics and social–emotional functioning among infants/toddlers with autism traits

Some markers of mirroring appear intact in schizophrenia: evidence from mu suppression

Although schizophrenia is associated with impairments in social cognition, the scope and neural correlates of these disturbances are largely unknown. In this study, we investigated whether schizophrenia patients show impaired functioning of the mirror neuron system (MNS), as indexed by electroencephalographic (EEG) mu (8-13 Hz) suppression, a hypothesized biomarker of MNS activity that is sensitive to the degree of social interaction depicted in visual stimuli. A total of 32 outpatients and 26 healthy controls completed an EEG paradigm that included six action observation or execution conditions that differed in their degrees of social interaction. Participants also completed a validated empathy questionnaire. Across both groups, we found a significant linear increase in mu suppression across the conditions involving greater levels of social engagement and interaction, but no significant group or interaction effects. Patients self-reported diminished empathic concern and perspective taking, which showed some moderate relations to mu suppression levels. Thus, the schizophrenia group showed generally intact modulation of MNS functioning at the electrophysiological level, despite self-reporting empathic disturbances. The disturbances commonly seen on self-report, performance, and neuroimaging measures of mentalizing in schizophrenia may largely reflect difficulties with higher-level inferential processes about others' emotions, rather than a basic incapacity to share in these experiences