Measures of tonic and phasic activity of the locus coeruleus-norepinephrine system in children with autism spectrum disorder: An event-related potential and pupillometry study.
Autistic kids often show high resting arousal yet blunted brain and pupil reactions to new events, a profile tied more to ADHD symptoms than core autism.
01Research in Context
What this study did
Kaiser et al. (2022) watched the pupils and brain waves of the kids. Half had autism, half were typical. All were 6-12 years old.
The team recorded resting pupil size and quick pupil jumps to sounds. They also tracked event-related potentials, or ERPs. These show how fast the brain answers a stimulus.
What they found
Kids with autism had wider resting pupils, hinting at higher baseline arousal. Yet their pupils and ERPs gave smaller blips when sounds popped up.
Odd twist: the dampened blips linked stronger to ADHD scores than to autism traits. Core autism signs did not predict the size of the pupil jump.
How this fits with other research
Sun et al. (2023) saw a similar dull pupil dance in adults with autism judging faces. Both studies point to sluggish phasic responses across ages and tasks.
de Jonge et al. (2025) also hunt neural markers, but they use resting gamma waves to forecast language growth. Together the papers show varied brain metrics can flag different developmental paths.
Ohan et al. (2015) prove that many toddlers with autism gain average IQ by age nine. Yesol’s data add a live physiologic measure that might help spot which kids will make those gains.
Why it matters
You now have a quick, cheap clue: big resting pupil plus tiny stimulus jump may signal ADHD-like arousal issues inside your ASD caseload. If you see this pattern, consider adding self-regulation or attention goals, not just social ones. Track changes after intervention by snapping a 30-second pupil video before and after sessions; no extra gear beyond a tablet camera and free analysis app.
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Join Free →Film the child’s eye for 30 s before session; note resting pupil size, then present a brief click and watch for a quick constriction-dilation jump to gauge phasic response.
02At a glance
03Original abstract
A growing body of research suggests that locus coeruleus-norepinephrine (LC-NE) system may function differently in individuals with autism spectrum disorder (ASD). Understanding the dynamics of both tonic (resting pupil diameter) and phasic (pupil dilation response [PDR] and event-related potential [ERP]) indices may provide meaningful insights about the nature of LC-NE function in ASD. Twenty-four children with ASD and 27 age- and nonverbal-IQ matched typically developing (TD) children completed two experiments: (1) a resting eye-tracking task to measure tonic pupil diameter, and (2) a three-stimulus oddball paradigm to measure phasic responsivity using PDR and ERP. Consistent with prior reports, our results indicate that children with ASD exhibit increased tonic (resting pupil diameter) and reduced phasic (PDR and ERP) activity of the LC-NE system compared to their TD peers. For both groups, decreased phasic responsivity was associated with increased resting pupil diameter. Lastly, tonic and phasic LC-NE indices were primarily related to measures of attention-deficit/hyperactivity disorder (ADHD), and not ASD, symptomatology. These findings expand our understanding of neurophysiological differences present in ASD and demonstrate that aberrant LC-NE activation may be associated with atypical arousal and decreased responsivity to behaviorally-relevant information in ASD.
Autism research : official journal of the International Society for Autism Research, 2022 · doi:10.1038/s41467-019-12048-1