Cortical Patterns of Pleasurable Musical Chills Revealed by High-Density EEG

Abstract

Music has the capacity to elicit strong positive feelings in humans by activating the brain's reward system. Because group emotional dynamics is a central concern of social neurosciences, the study of emotion in natural/ecological conditions is gaining interest. This study aimed to show that high-density EEG (HD-EEG) is able to reveal patterns of cerebral activities previously identified by fMRI or PET scans when the subject experiences pleasurable musical chills. We used HD-EEG to record participants (11 female, 7 male) while listening to their favorite pleasurable chill-inducing musical excerpts; they reported their subjective emotional state from low pleasure up to chills. HD-EEG results showed an increase of theta activity in the prefrontal cortex when arousal and emotional ratings increased, which are associated with orbitofrontal cortex activation localized using source localization algorithms. In addition, we identified two specific patterns of chills: a decreased theta activity in the right central region, which could reflect supplementary motor area activation during chills and may be related to rhythmic anticipation processing, and a decreased theta activity in the right temporal region, which may be related to musical appreciation and could reflect the right superior temporal gyrus activity. The alpha frontal/prefrontal asymmetry did not reflect the felt emotional pleasure, but the increased frontal beta to alpha ratio (measure of arousal) corresponded to increased emotional ratings. These results suggest that EEG may be a reliable method and a promising tool for the investigation of group musical pleasure through musical reward processing.

Keywords: EEG; cerebral activity; chills; emotion; high density EEG; music; musical reward; peak pleasure.

FIGURE 1

Representation of the experimental procedure. Eight extracts (five chill-inducing extracts and three neutral extracts) were listened to. Extracts were 90 s long and calibrated to start 60 s before indicated chill-inducing moments.

FIGURE 2

Region of interest for EEG analysis, LPF, left prefrontal; RPF, right prefrontal; LF, left frontal; RF, right frontal; LT, left temporal; RT, right temporal; LC, left central; RC, right central.

FIGURE 3

(A) Comparison of power spectral density (μV²/Hz) values in the theta and alpha frequency range for each condition (LP, low pleasure; HP, high pleasure; Chills) in the prefrontal, frontal, central, and temporal ROIs (*p < 0.05, **p < 0.01, errors bars represent SEM). (B) Surface topography for each condition showed an increased positivity for chills and a gradually increasing positivity in parieto-central sites as the emotion increased (μV).

FIGURE 4

Comparison of power spectral density (μV²/Hz) value for each condition (LP, low pleasure; HP, high pleasure; Chills) for beta to alpha ratio, frontal asymmetry, and prefrontal asymmetry (*p < 0.05, errors bars represent SEM).

FIGURE 5

(A) Current source density (μA/mm³) for each condition (LP, low pleasure; HP, high pleasure; Chills) for the supplementary motor area, bilateral insula, orbitofrontal cortex, and superior temporal gyri. (B) Representation of cortical activations (μA/mm³) for the orbito-frontal cortex/VmPFC complex in the sagittal and the transversal planes (*p < 0.01, **p < 0.001, ***p < 0.0001, ****p < 1.10^–5, errors bars represent SEM).