Structural-morphometric examination of thalamic nuclei in individuals with autism spectrum disorders

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] The thalamus has been implicated as a potential source of neural disruption in autism spectrum disorders (ASD). This subcortical nuclear complex is critically involved in sensory processing, an area of deficit in ASD. Whereas previous research reported atypical thalamic volume patterns in this population (Hardan, et al., 2007; Lin, et al., 2015; Tsatsanis, et al., 2003), the pattern of results across studies remains inconsistent. Differences in experimental design (e.g., analysis software, segmentation approach, participant sample characteristics), as well as limitations of conventional imaging techniques (e.g., insufficient image resolution), may have contributed to disparate findings. Given these discrepancies and methodological constraints, the exact nature of thalamic abnormalities in ASD remains unclear. The present study sought to examine ASD-related differences in morphometric features of the thalamus. DTI-based segmentation in conjunction with a statistical clustering algorithm were employed to evaluate volumetric properties of the thalamic nuclei in a sample of individuals with and without ASD. Nuclei clustering results do not correspond in size, shape, nor location to estimations provided by a standardized atlas of the human thalamus (Morel, 2007). Clustering results are not consistent with previous research findings (Wiegell, et al., 2003). Results suggest that this segmentation approach is unable to reliably resolve the major thalamic nuclei within the context of the current experimental design. Findings highlight the sensitivity of DTI-based segmentation to different data processing methods and thus identify considerations for methodological development and help evaluate the utility of alternative segmentation approaches for future investigations.