A new study published in the Journal of Imaging Neuroscience looked at the Lateral Occipitotemporal Cortex (LOTC), a brain region crucial for body part representation, to compare the representational structure of body parts between adults with Austin Spectrum Disorder (ASD) and typically developing (TD) adults.
“Individuals with ASD often struggle to interpret emotions and intentions from others’ faces and bodies,” study author Yuto Kurihara told us. “This communication challenge has long been debated as stemming from either basic visual processing deficits or higher-order cognitive problems.”
However, the fundamental perception of the body itself, Kurihara explained, specifically, how different body parts are visually distinguished in the brain, has not been sufficiently investigated.
“Adults with ASD often struggle to understand the meaning of body gestures. If this difficulty stemmed from an abnormality in body perception itself, it would be expected their body representation structure to differ from that of TD adults,” Kurihara told us. « Conversely, if the issue lies in higher-order processing (e.g., interpreting emotions, intentions, and social contexts), than their lower-level visual body representation structure should be similar. Our research investigated this latter possibility.”
While the behaviors of individuals with ASD may appear different from those of TD individuals at first glance, the researchers hypothesized that these differences were not fundamental. Their research aimed to elucidate the specific brain processes that underlie these differences from TD individuals.
“We measured brain activity in the Lateral Occipitotemporal Cortex (LOTC) using functional Magnetic Resonance Imaging (fMRI) while participants performed a 1-back task with body part images (e.g., faces, hands, arms, legs, chest, waist),” Kurihara told us. “In this task, participants judged whether the current image was the same as the previous one.”
The research team applied a multivariate pattern analysis technique called Representational Similarity Analysis (RSA) to the measured brain activity data. RSA can reveal how different stimuli are grouped or related in the brain by focusing on the similarity between spatial brain response patterns to different stimuli. This analysis allowed the researchers to investigate the structural categorization rather than merely the strength of responses. In this study, the researchers used RSA to compare the representational structure of body parts between the ASD and TD groups.
“In both the ASD and TD groups, body parts were organized into three semantic groups within the bilateral LOTC: faces, action effector body parts, and non-effector body parts,” Kurihara told us. « This implies that visual categorization of the body is appropriate for ASD and TD individuals. Furthermore, the body part representations obtained from the RSA showed statistically significant similarity between the two groups. Thus, it is clear that the structure of body part representations is similar in both TDs and ASDs.”
The results suggest that the difficulties in social interaction experienced by individuals with ASD may stem from differences in brain function other than the perception of the body itself.
“This a crucial finding, suggesting that the communication difficulties characteristic of ASD may not stem from differences in the fundamental visual processing of body parts within the LOTC,” Kurihara told us. “This insight suggests that the challenges experienced by individuals with ASD in this context are less about a difference in sensory representation itself, and more likely rooted in higher-order functions, such as the interpretation and social use of that information. Clarifying this distinction can help dispel misunderstandings and prejudices. Based on the insights from this study, we hope to contribute to the development of appropriate support for individuals with ASD and foster a more inclusive society.”