Sensory overresponsivity (SOR), an atypical negative reaction to sensory stimuli, is a relatively common feature of autism, although the degree of SOR can be highly variable. Previous work has shown that SOR may reflect both a reduced degree of habituation to sensory stimuli as well as reduced regulation of amygdala responses to such stimuli. Atypical but distinct neural responses may be seen in individuals with autism across the range of sensory responsiveness.

Now, SFARI Investigator Susan Bookheimer and colleagues have used functional magnetic resonance imaging (fMRI) to deepen our understanding of atypical neural responses underpinning SOR in autism, with possible implications for the design of interventions.

In the new work — partly funded by a SFARI Pilot Award — the team carried out an fMRI study of 42 children and adolescents with autism, as well as 27 typically developing control subjects. Individuals with autism were divided into high-SOR and low-SOR groups. Brain responses were measured in somatosensory, auditory, visual and prefrontal cortices, as well as amygdala, in response to joint auditory and tactile stimuli across six blocks of time.

They observed that the key SOR group difference is in the pattern of connectivity across sensory exposure: the high-SOR group showed initial but unsustained amygdala-prefrontal connectivity, whereas the low-SOR group switched from positive to negative amygdala-prefrontal connectivity across sensory exposure. Moreover, the low-SOR group uniquely lacked neural responsiveness to new but similar stimuli, suggesting a degree of overgeneralization.