Title: Brainstem white matter uniquely predicts sensory features in autistic children
Legend: The goal of this research was to determine how sensory features, such as increased or decreased sensitivity to the environment, are associated with the brainstem in autistic and non-autistic children (6.0-11.0 years-old). The brainstem is an early developing and anatomically complex brain structure that transmit sensory and motor information between the cerebrum and the body. Panel A depicts the brainstem white matter pathways where relationships between white matter structure and sensory features were unique in autistic and non-autistic groups. A graph showing these relationships within the cortico-pontine pathways (displayed in blue) shows the typical pattern of results. Follow-up analyses aimed to determine if these brain-sensory relationships were specific to the brainstem or representative of a broader whole-brain pattern. Panel B shows areas across the entire brain where white matter was uniquely related to sensory features in autistic children. While the brainstem represented only a small proportion of the search space (7%), it contained a large proportion of the total findings. Specifically, after normalizing for search space, almost a quarter (24%) of brainstem white matter was associated with sensory features in autistic children, compared to only 11% of cerebral white matter. Together, these findings suggest that the brainstem may largely contribute to sensory features in autistic children but in a way that is distinct from non-autistic children.
Citation: Surgent, O., Riaz, A., Ausderau, K. K., Adluru, N., Kirk, G. R., Guerrero-Gonzalez, J., Skaletski, E. C., Kecskemeti, S. R., Dean Iii, D. C., Weismer, S. E., Alexander, A. L., & Travers, B. G. (2022). Brainstem white matter microstructure is associated with hyporesponsiveness and overall sensory features in autistic children. Molecular autism, 13(1), 48. https://doi.org/10.1186/s13229-022-00524-3
Background: Elevated or reduced responses to sensory stimuli, known as sensory features, are common in autistic individuals and often impact quality of life. Little is known about the neurobiological basis of sensory features in autistic children. However, the brainstem may offer critical insights as it has been associated with both basic sensory processing and core features of autism.
Methods: Diffusion-weighted imaging (DWI) and parent-report of sensory features were acquired from 133 children (61 autistic children with and 72 non-autistic children, 6-11 years-old). Leveraging novel DWI processing techniques, we investigated the relationship between sensory features and white matter microstructure properties (free-water-elimination-corrected fractional anisotropy [FA] and mean diffusivity [MD]) in precisely delineated brainstem white matter tracts. Follow-up analyses assessed relationships between microstructure and sensory response patterns/modalities and analyzed whole brain white matter using voxel-based analysis.
Results: Results revealed distinct relationships between brainstem microstructure and sensory features in autistic children compared to non-autistic children. In autistic children, more prominent sensory features were generally associated with lower MD. Further, in autistic children, sensory hyporesponsiveness and tactile responsivity were strongly associated with white matter microstructure in nearly all brainstem tracts. Follow-up voxel-based analyses confirmed that these relationships were more prominent in the brainstem/cerebellum, with additional sensory-brain findings in the autistic group in the white matter of the primary motor and somatosensory cortices, the occipital lobe, the inferior parietal lobe, and the thalamic projections.
Limitations: All participants communicated via spoken language and acclimated to the sensory environment of an MRI session, which should be considered when assessing the generalizability of this work to the whole of the autism spectrum.
Conclusions: These findings suggest unique brainstem white matter contributions to sensory features in autistic children compared to non-autistic children. The brainstem correlates of sensory features underscore the potential reflex-like nature of behavioral responses to sensory stimuli in autism and have implications for how we conceptualize and address sensory features in autistic populations.
About the Lab: The Motor Brain and Development Lab is dedicated to advancing knowledge about motor development, brain development, and independent living skills to promote and enhance quality of life for individuals with and without developmental disorders. Our current projects specialize in examining motor and brain development in individuals on the autism spectrum.
Investigator: Brittany G. Travers, PhD