Ultra-high resolution imaging of laminar thickness in face-selective cortex in autism

Gray matter cortical thickness (CT) is related to perceptual abilities. The fusiform face area (FFA) (Kanwisher et al., The Journal of Neuroscience: The Official Journal of the Society for Neuroscience, 17, 4302-4311, 1997) in the inferior temporal lobe is defined by its face selectivity, and the CT of the FFA correlates with the ability to make difficult visual decisions (Bi et al., Current Biology, 24, 222-227, 2014; McGugin et al., Journal of Cognitive Neuroscience, 28, 282-294, 2016, Journal of Cognitive Neuroscience, 32, 1316-1329, 2020). In McGugin et al. Journal of Cognitive Neuroscience, 32, 1316-1329, (2020), individuals with better face recognition had relatively thinner FFAs, whereas those with better car recognition had thicker FFAs. This opposite correlation effect (OCE) for faces and cars was pronounced when we look selectively at the deepest laminar subdivision of the FFA. The OCE is thought to arise because car and face recognition abilities are fine-tuned by experience during different developmental periods. Given autism's impact on face recognition development, we predicted the OCE would not appear in autistic individuals. Our results replicate the OCE in total FFA thickness and in deep layers in neurotypical adults. Importantly, we find a significant reduction of these effects in adults with autism. This supports the idea that the OCE observed in neurotypical adults has a developmental basis. The abnormal OCE in autism is specific to the right FFA, suggesting that group differences depend on local specialization of the FFA, which did not occur in autistic individuals.