Sensory processing sensitivity and somatosensory brain activation when feeling touch

Abstract

Sensory processing sensitivity is described as a personality trait associated with a high sensitivity to environmental and social stimuli. It has been assumed that about 15–20% of the total population can be described as highly sensitive. The concept states that those individuals represent a higher sensitivity to subtle stimuli, thereby exhibiting a different somatic sensation. Here we aim to test the assumption that the brain’s sensory perception is different in individuals with high sensory processing sensitivity. We used a German version of the Highly Sensitive Person scale to measure sensory processing sensitivity. Furthermore, we assessed the Big Five personality dimensions and trait empathy (using IRI). To test the hypothesis that the brain’s handling of sensory information is different in individuals with high sensory-processing sensitivity, we scanned participant’s brain activity with functional magnetic resonance imaging (fMRI) while they were touched by an experimenter’s hand. Results showed positive correlations of sensory processing sensitivity with neuroticism, openness, and empathy. Introversion was not a significant predictor. Neuroimaging data demonstrated that sensory processing sensitivity (controlled for associated personality dimensions) was not related to primary or secondary somatosensory BOLD responses, but positively associated with BOLD activity in left posterior insular cortex. Based on these results we conclude that sensory processing sensitivity seems to represent insula-mediated affective touch. We discuss these results with previous studies reporting an engagement of the insula in individuals with high sensory processing sensitivity.