Modulation of bodily response to chill stimuli by impaired structural connectivity of the left insula- a functional and lesion quantification study in stroke patients.

Abstract

The insula has important function in monitoring and integrating physiological responses to a personal experience of multimodal input. The experience of chills in response to auditory stimuli is an important example for a relevant arousing experience coupled with bodily response. A group study about altered chill experiences in patients with insula lesions is lacking. We investigated 28 stroke patients with predominantly insula lesions in the chronic stage and 14 age matched controls using chill stimuli of both valences (music, harsh sounds). We analyzed group differences in subjective chill reports, associated bodily responses (skin conductance response, SCR), lesion mapping, diffusion weighted imaging and functional magnetic resonance imaging (fMRI). Other neuropsychological deficits were excluded by comprehensive testing. Diffusion weighted imaging was quantified for four insula tracts using fractional anisotropy. Frequency of chill experiences was comparable between participant groups. However, bodily responses were decreased for the stroke group. Whereas there was no association of lesion location we found a positive association for the SCR during aversive sounds and the tract connecting anterior inferior insula and left temporal pole in the stroke group. Similarly, fMRI-activation in areas hypothesized to compensate for damage was increased with bodily response. We observed a decoupling of felt arousal and bodily response after insula lesion. Impaired bodily response was related to an impaired interaction of the left anterior insula and the temporal pole.