Researchers have identified a distinct pattern of brain activity in neurodiverse children who experience sensory over-responsivity. The findings suggest that children who are highly sensitive to everyday stimuli may unknowingly regulate their neural networks to cope with overwhelming sights and sounds. The study was published in the Journal of Neurodevelopmental Disorders.
Sensory processing challenges are a frequent concern for parents and clinicians. These issues often manifest as sensory over-responsivity. Children with this condition experience intense physical or emotional reactions to stimuli that others might find harmless or mundane.
Common triggers include the texture of clothing seams, the sound of a vacuum cleaner, or bright fluorescent lights. While these reactions are often observed in children with autism or attention deficit hyperactivity disorder, they also occur in children without a specific diagnosis.
The biological mechanisms behind these intense reactions have remained largely elusive. Diagnosis currently relies on caregiver reports and clinical observations rather than biological markers. To address this gap, a team of researchers sought to map the neural underpinnings of sensory over-responsivity. They aimed to understand how different brain systems interact when a child processes sensory information.
The study was conducted by a multidisciplinary team. The lead investigators included Pratik Mukherjee, a professor of radiology and biomedical imaging, and Elysa Marco, a pediatric neurologist. Both are affiliated with the University of California, San Francisco. They collaborated with researchers from Cortica Healthcare and other institutions.
The investigators based their analysis on a framework of two opposing brain systems. They categorized these as exogenous and endogenous systems. The exogenous system involves brain networks that face outward. It includes regions responsible for processing vision, touch, and movement. This system helps the brain interpret raw data coming from the external environment.
In contrast, the endogenous system focuses inward. It includes networks responsible for attention, decision-making, and emotional regulation. This system handles higher-level cognitive tasks. It allows an individual to plan actions, control impulses, and attribute meaning to experiences. The researchers hypothesized that the balance between these two systems might look different in children who struggle with sensory regulation.
To test this hypothesis, the team recruited 83 children between the ages of 8 and 12. All participants were recruited from a community neurodevelopment center. They screened the children to ensure they were neurodiverse, meaning they had a high likelihood of a developmental condition such as ADHD or learning differences. However, the researchers specifically excluded children with a confirmed autism diagnosis to reduce variability in the sample.
Clinicians assessed the children using a structured evaluation called the Sensory Processing 3 Dimensions Assessment. Based on this direct observation, the children were divided into two groups. One group consisted of 39 children who exhibited sensory over-responsivity. The second group consisted of 44 neurodiverse children who did not show these specific sensory sensitivities.
The researchers used magnetic resonance imaging to scan the brains of all participants. They employed a technique known as resting-state functional MRI. This method measures spontaneous fluctuations in brain activity while the subject is at rest. It allows scientists to see which brain regions are communicating with each other.
The imaging results revealed a striking divergence between the two groups. In the children with sensory over-responsivity, the researchers observed a reduction in connectivity within the exogenous networks. Specifically, the areas of the brain dedicated to vision and motor control showed lower levels of local synchronization. It appeared as though the brain was dampening its connection to the sensory world.
Simultaneously, these same children showed elevated connectivity within the endogenous networks. The brain regions associated with attention and cognitive control were highly active and synchronized. This pattern created a distinct neural signature. The inward-facing systems were dialed up, while the outward-facing systems were dialed down.
The neurodiverse children without sensory issues displayed the exact opposite pattern. In this group, the exogenous sensory networks were highly connected. Conversely, their endogenous regulation networks showed lower levels of connectivity. This created a clear “double dissociation” between the two groups. The functional organization of their brains appeared to be diametrically opposed depending on their sensory responsiveness.
This contrast was evident in both long-range and local brain connections. Long-range connectivity refers to communication between distant brain regions. Local connectivity refers to synchronization among neighboring neurons. The study found that children with sensory over-responsivity had generally weaker long-range connections across the brain. However, the local hyper-connectivity in their regulatory networks was a standout feature.
The researchers also examined the structural integrity of the brain’s white matter. White matter acts as the cabling that connects different brain regions. Using diffusion tensor imaging, the team found that children with sensory sensitivities had reduced structural integrity in specific pathways. These pathways included the posterior thalamic radiations, which carry visual information, and the internal capsule, which carries touch and motor signals.
To understand the practical implications of these brain patterns, the researchers looked at behavioral data. They assessed how well the children managed their emotions in daily life. They classified the children as either “resilient” or “dysregulated” based on parent reports. Resilient children were better at adapting to change and recovering from setbacks. Dysregulated children struggled more with anger and emotional control.
The study found that the distinct brain pattern—low sensory connectivity and high regulatory connectivity—was strongest in the resilient children with sensory over-responsivity. This suggests that the brain pattern may be an adaptive mechanism. A child who is easily overwhelmed by sensory input might subconsciously suppress their sensory networks to reduce the noise. At the same time, they may upregulate their cognitive control networks to maintain composure.
For the dysregulated children, this distinct separation of brain systems was less apparent. Their brain activity did not show the same clear compensatory shift. This implies that the ability to modulate these two systems is linked to better emotional and behavioral outcomes. The unique neural signature identified by the researchers seems to be a marker of successful coping in the face of sensory overload.
Pratik Mukherjee noted the logic behind this physiological response. He explained, “We think that when you are overstimulated by sensory input, you compensate by dialing up your brain’s inward-focused networks to gain self-control. You also dial down your outward-focused networks to minimize sensory input.” He added that children who are not overwhelmed do not need to employ this strategy.
The research team also tested whether these brain patterns could be used for diagnosis. They utilized machine learning algorithms to analyze the imaging data. By combining functional MRI data with structural white matter data, the algorithms could classify children with high accuracy. The model distinguished between children with and without sensory over-responsivity with nearly 90 percent accuracy.
This high level of classification suggests that sensory over-responsivity has a robust biological basis. It is not merely a behavioral preference or a symptom of other conditions. It involves measurable changes in how the brain is wired and how it functions. The ability to identify these markers could eventually lead to objective diagnostic tools.
There are several caveats to consider regarding this research. The sample size of 83 children is relatively small for a neuroimaging study. The findings will need to be replicated in larger, independent cohorts to ensure they are distinct and universal. Additionally, the study excluded children with autism. Since sensory issues are highly prevalent in autism, it remains unknown if these specific findings apply to that population.
The cross-sectional nature of the study also limits conclusions about cause and effect. The researchers looked at the children at a single point in time. It is not yet clear when these brain patterns emerge in development. Longitudinal studies following children from infancy through adolescence would be necessary to track how these networks develop. Such studies could determine if the brain patterns precede the sensory issues or develop as a response to them.
Future research directions include investigating how these brain networks respond to treatment. Occupational therapy is a common intervention for sensory processing challenges. Researchers could use these imaging techniques to see if therapy changes brain connectivity. If the brain pattern is indeed a coping mechanism, successful therapy might alter the need for such strong downregulation of sensory networks.
The study, “A neural substrate for sensory over-responsivity defined by exogenous and endogenous brain systems,” was authored by Hannah L. Choi, Maia C. Lazerwitz, Rachel Powers, Mikaela Rowe, Jamie Wren-Jarvis, Amir Sadikov, Lanya T. Cai, Robyn Chu, LaShelle Rullan, Kaitlyn J. Trimarchi, Rafael D. Garcia, Elysa J. Marco & Pratik Mukherjee.
