Brain connectivity patterns map onto sensory processing styles in autistic youth

A recent investigation presents evidence that distinct patterns of brain connectivity can be linked to the various sensory experiences observed in autistic youth. Researchers from Western University discovered that the functional connections between brain regions could predict an autistic child’s sensory profile with considerable accuracy.

The study, published in the journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, found that sensory processing differences characterize up to 87 percent of individuals on the autism spectrum. These differences manifest in the form of heightened or diminished sensitivity to sensory stimuli such as light, sound, texture, smell, or taste.

Some autistic individuals actively seek out specific sensory inputs, while others must avoid common sensory experiences entirely. While these sensory variations appear highly personalized, prior research has indicated they tend to cluster into specific behavioral categories. Previous research had identified five distinct sensory phenotypes among autistic youth: sensory adaptive, generalized sensory differences, and three more specialized profiles involving selective sensitivities or unique sensory seeking behaviors.

Until now, the relationship between these behavioral profiles and the brain's internal wiring remained unclear. To explore this connection, researchers led by Matthew Kolisnyk and Ryan Stevenson analyzed data from 146 autistic children and adolescents aged three to twenty-one. Caregivers completed clinical questionnaires detailing the children's responses to various sensory stimuli, allowing researchers to categorize each participant into one of the five established sensory phenotypes.

Participants then underwent resting-state functional magnetic resonance imaging (fMRI), which measures brain activity with minimal mental effort. By tracking blood oxygen levels, researchers mapped the brain's functional connectivity, revealing how different neural regions communicate and share information. The scans were divided into 200 sections of the cerebral cortex and 32 subcortical regions deep within the brain.

Researchers applied graph theory to quantify brain network connectivity, assessing metrics such as the strength of connections between regions and the efficiency of information transfer. Additional calculations determined whether certain brain regions functioned as central hubs for long-distance communication or how highly interconnected a region's neighbors were.

The resulting data points generated detailed descriptions of each participant's unique brain network. These measurements were then fed into a machine learning algorithm, which learned to recognize patterns in the connectivity data and predict each child's sensory phenotype. The algorithm successfully differentiated between seven of the ten possible pairs of sensory phenotypes based solely on their brain connectivity metrics.

The model performed best when distinguishing between the sensory adaptive group and the group with generalized sensory differences. Specific brain networks emerged as strong predictors of a child's sensory profile. Children in the sensory adaptive group exhibited stronger global connections in the prefrontal cortex, which is involved in decision-making and executive function.

They also showed high connectivity in the orbitofrontal cortex, an area above the eyes that integrates sensory information with emotional rewards. Conversely, children with generalized sensory differences displayed stronger local connections within the somatomotor network, which handles touch and voluntary movement. Their primary sensory processing regions were highly interconnected locally but lacked strong connections to the prefrontal cortex, indicating a potential difference in how higher-level brain regions modulate incoming sensory signals.

The analysis also identified distinct connectivity signatures for the more specialized sensory profiles. Children with isolated taste and smell sensitivities showed unique patterns of brain connectivity. These findings provide insights into the biological diversity within the autism spectrum and could help explain the wide range of sensory experiences observed in autistic individuals.