Neural correlates of social motor coordination in autism: A systematic review and meta-analysis of fNIRS studies.

This research looked at how autistic people's brains work differently when doing activities with others, like coordinating movements. Brain scans showed autistic people rely more on watching movements and less on understanding social cues. The severity of autism symptoms affects how the brain processes these shared activities. This helps explain why some autistic people may find it challenging to coordinate with others in social situations.

This systematic review and meta-analysis examined neural differences in social motor coordination between autistic and neurotypical individuals using functional near-infrared spectroscopy (fNIRS) across 11 studies. Key findings revealed that autistic individuals showed increased activation in the inferior parietal lobule (IPL) and reduced activation in the superior temporal sulcus (STS) during joint action tasks. This pattern suggests greater reliance on kinematic processing and diminished engagement with socially relevant information. Inter-brain synchrony analysis showed trends toward reduced reciprocal processing in autism, particularly in predicting partner mental states.

Importantly, autism severity influenced neural-behavioral associations, with mild versus moderate-to-severe symptoms showing distinct patterns, highlighting the complexity of social motor coordination in autism.

Findings suggest autism involves distinct neural strategies for social coordination rather than simple deficits. Different activation patterns indicate compensatory mechanisms that could inform intervention design. Autism severity should guide individualized approaches to social motor coordination training and therapeutic interventions.

Limited to fNIRS studies only, small number of studies included (11 total, 9 in meta-analysis), sample sizes not reported, inter-brain synchrony effects not statistically significant, and visual inspection methods used for severity analysis rather than quantitative measures.

This study aimed to provide a comprehensive overview of how individuals with autism spectrum condition (ASC) process social motor coordination, focusing on joint action and its neural correlates, as examined through functional near-infrared spectroscopy (fNIRS) in comparing to their neurotypical (NT) counterparts. Eleven studies were analyzed, with nine included in the meta-analysis. The results identified the inferior parietal lobule (IPL) and superior temporal sulcus (STS) as significant moderators explaining group differences in cortical activation during joint action. Specifically, individuals with ASC showed increased IPL activation and reduced STS activation, indicating a greater reliance on kinematic processing and diminished engagement in encoding and integrating socially relevant information.

Although the pooled effect size for inter-brain synchrony (IBS) was not statistically significant, descriptive analyses showed a trend toward reduced reciprocal processing in ASC, particularly in predicting and aligning with a partner's mental states, as supported by decreased IBS in the temporoparietal junction (TPJ). Furthermore, a visual inspection of behavioral and neural outcomes by autism severity exhibited distinct tendencies. Individuals with mild symptoms demonstrated different neural-behavioral associations compared to those with moderate-to-severe symptoms, suggesting that symptom severity influences how neural processing supports joint action. These findings highlight the differential involvement of neural systems in joint actions among individuals with ASC depending on task type and autism severity, and emphasize the distinction between intra- and inter-personal processing.

By integrating these findings, this study offers a more integrative perspective on social motor coordination in ASC as a complex, multi-dimensional process.