Exploring Sensory Hypersensitivity in Infants: How EEG is Shaping Our Understanding

Sensory processing issues in infants are more common than many might think, with studies showing that approximately 5–13% of children aged 4–6 years and 11.4% of children aged 3-14 years, experience sensory difficulties. These challenges can significantly impact daily life, leading to issues like sleep disturbances and dietary imbalances, which in turn place considerable stress on parents.

Traditionally, the assessment of sensory difficulties has relied heavily on parent-reported questionnaires, such as the Infant/Toddler Sensory Profile (ITSP). However, these subjective measures have limitations, as they can be influenced by various factors and may not provide a complete picture of the child's sensory processing abilities. To address these limitations, researchers have turned to more objective measures, such as electroencephalography (EEG), to better understand the neural mechanisms underlying sensory hypersensitivity. 

EEG is a powerful tool that allows researchers to measure brain activity in real-time by recording electrical signals produced by neurons in the brain. One of the key advantages of EEG is its ability to capture event-related potentials (ERPs), which are brain responses that are directly related to specific sensory events, such as a touch or a sound. By analysing these responses, researchers can gain insights into how the brain processes sensory information. In the context of sensory hypersensitivity, EEG can provide valuable information about how infants' brains respond to tactile stimuli. Specifically, somatosensory-evoked potentials (SEPs) are measured in response to tactile stimulation, and abnormalities in SEP amplitude and latency can indicate differences in sensory processing. For example, previous research has shown that infants with hypersensitivity may exhibit abnormal SEP patterns, which could be linked to the heightened sensory responses that characterise this condition. 

TruScan Research EEG System in Infant Research 

A recent study conducted by Kamiya et al. (2024) at Osaka University, used the TruScan EEG system to investigate the neural correlates of sensory hypersensitivity in infants. TruScan EEG is a state-of-the-art device that offers high-resolution EEG recording with 19 channels, making it ideal for capturing the subtle neural signals associated with sensory processing in young children.

During the study, infants were held in their parents' laps while a tactile stimulus was applied to the sole of their feet using a specially designed vibrator. The EEG data collected by the TruScan system allowed the researchers to analyse SEPs and measure the coherence between different brain regions, providing insights into how sensory information is processed in the infant brain.

One of the key findings of the study was that the latency of the N2 component of the SEP, a marker of early sensory processing, was positively correlated with hypersensitivity. This suggests that infants who are hypersensitive may have delayed neural responses to tactile stimuli, which could contribute to their heightened sensory experiences. Additionally, the researchers found that inter-hemispheric coherence, particularly in the delta frequency band, was associated with sensory hypersensitivity. This indicates that hypersensitivity may be related to altered connectivity between brain regions involved in sensory processing.