Diminished Repetition Suppression Reveals Selective and Systems-Level Face Processing Differences in ASD.

Researchers used brain scans to study how autistic and non-autistic adults process repeated images and sounds. They found that autistic people had difficulty with brain responses specifically when seeing faces repeatedly, but not with objects or words. This face-processing difference was linked to greater social communication challenges and showed up as differences in brain connections related to recognizing faces.

This fMRI study compared repetition suppression (RS) - the brain's reduced response to repeated stimuli - between autistic and neurotypical adults across multiple stimulus categories. While typically developing individuals show robust RS as a sign of neural efficiency and learning, the research found that autistic individuals showed specifically reduced RS for faces only, not for objects, printed words, or spoken words. This selective deficit in face processing was associated with greater social communication challenges and accompanied by altered brain connectivity and white matter differences in face-recognition networks. The findings suggest that fundamental neural mechanisms supporting face processing are selectively disrupted in autism, which may contribute to social communication difficulties.

Findings suggest face-processing interventions may be particularly relevant for autistic individuals with social communication challenges. Results support targeted approaches focusing on face recognition and social visual processing rather than broad sensory interventions.

Sample size not reported in abstract. Study design unclear from available information. Cross-sectional design cannot establish causality. Generalizability to broader autism population uncertain without demographic details.

Repeated exposure to a stimulus results in reduced neural response, or repetition suppression, in brain regions responsible for processing that stimulus. This rapid accommodation to repetition is thought to underlie learning, stimulus selectivity, and strengthening of perceptual expectations. Importantly, reduced sensitivity to repetition has been identified in several neurodevelopmental, learning, and psychiatric disorders, including autism spectrum disorder (ASD), a neurodevelopmental disorder characterized by challenges in social communication and repetitive behaviors and restricted interests. Reduced ability to exploit or learn from repetition in ASD is hypothesized to contribute to sensory hypersensitivities, and parallels several theoretical frameworks claiming that ASD individuals show difficulty using regularities in the environment to facilitate behavior.

Using fMRI in autistic and neurotypical human adults (females and males), we assessed the status of repetition suppression across two modalities (vision, audition) and with four stimulus categories (faces, objects, printed words, and spoken words). ASD individuals showed domain-specific reductions in repetition suppression for face stimuli only, but not for objects, printed words, or spoken words. Reduced repetition suppression for faces was associated with greater challenges in social communication in ASD. We also found altered functional connectivity between atypically adapting cortical regions and higher-order face recognition regions, and microstructural differences in related white matter tracts in ASD.

These results suggest that fundamental neural mechanisms and system-wide circuits are selectively altered for face processing in ASD and enhance our understanding of how disruptions in the formation of stable face representations may relate to higher-order social communication processes.A common finding in neuroscience is that repetition results in plasticity in stimulus-specific processing regions, reflecting selectivity and adaptation (repetition suppression [RS]). RS is reduced in several neurodevelopmental and psychiatric conditions including autism spectrum disorder (ASD). Theoretical frameworks of ASD posit that reduced adaptation may contribute to associated challenges in social communication and sensory processing. However, the scope of RS differences in ASD is unknown.

We examined RS for multiple categories across visual and auditory domains (faces, objects, printed words, spoken words) in autistic and neurotypical individuals. We found reduced RS in ASD for face stimuli only and altered functional connectivity and white matter microstructure between cortical face-recognition areas. RS magnitude correlated with social communication challenges among autistic individuals.