Brain–heart dynamics during emotional processing under uncertain conditions: An index of depression risk

Abstract

Recent studies highlight interoception as the key to processing healthy emotion and pathophysiology of affective disorders such as major depressive disorder (MDD). It has been reported that interoceptive responses are impaired in MDD and in healthy individuals with a high depressive risk (HDR). However, it is unclear how individual differences in HDR relate to neurophysiological underpinnings for interoceptive and emotional reactions under different degrees of certainty. We examined whether HDR mediates the relationship between a neuro-physiological marker for interoception, heartbeat-evoked potential (HEP), and an index for cardiac reactivity, heart rate (HR) or heart rate variability (HRV). In a concurrent EEG-ECG experiment, 26 healthy participants underwent an emotion-evoking picture evaluation task. One of three differential auditory tones associated with a level of certainty preceded display of a pleasant or unpleasant picture. The results showed attenuated HRV activity for certain cues in HDR individuals. Neural and physiological reactions to uncertain, unpleasant pictures were enhanced by the depressive risk. These results suggest reduced responses in prediction processing and enlarged precision-weighted prediction error for unpleasant pictures. Finally, HDR significantly mediated the HEP and HR relationship for unexpected unpleasant stimuli. Our study thus provides evidence that interoceptive predictive coding in the cardiac domain is altered by HDR, and suggests that investigating the heart-brain interaction related to predictive coding will offer insights into how to estimate the level of depressive risk.