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

BACKGROUND AND PURPOSE

The insula has important functions 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.

METHODS

Twenty-eight stroke patients with predominantly insula lesions in the chronic stage and 14 age-matched controls were investigated using chill stimuli of both valences (music, harsh sounds). Group differences were analyzed in subjective chill reports, associated bodily responses (skin conductance response), lesion mapping, diffusion-weighted imaging and functional magnetic resonance imaging. Other neuropsychological deficits were excluded by comprehensive testing. Diffusion-weighted imaging was quantified for four insula tracts using fractional anisotropy.

RESULTS

The 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, a positive association was found for the skin conductance response during aversive sounds and the tract connecting anterior inferior insula and left temporal pole in the stroke group. Similarly, functional magnetic resonance imaging activation in areas hypothesized to compensate for damage was increased with bodily response.

CONCLUSIONS

A decoupling of felt arousal and bodily response after insula lesion was observed. Impaired bodily response was related to an impaired interaction of the left anterior insula and the temporal pole.