Similarities and differences in the induction and regulation of the negative emotions fear and disgust: A functional near infrared spectroscopy study

Abstract

Affective processing, including induction and regulation of emotion, activates neural networks, induces physiological responses, and generates subjective experience. Dysregulation of these processes can lead to maladaptive behavior and even psychiatric morbidity. Multimodal studies of emotion thus not only help elucidate the nature of emotion, but also contribute to important clinical insights. In the present study, we compared the induction (EI) and effortful regulation (ER) with reappraisal of fear and disgust in healthy subjects using functional near infrared spectroscopy (fNIRS) in conjunction with electrodermal activity (EDA). During EI, there was significant activation in medial prefrontal cortex (PFC) for fear and more widespread activation for disgust, with right lateral PFC significantly more active during disgust compared to fear. ER was equally effective for fear and disgust reducing subjective emotion rating by roughly 45%. Compared to baseline, there was no increased PFC activity for fear during ER, while for disgust lateral PFC was significantly more active. Significant differences between the two negative emotions were also observed in sympathetic nerve activity as reflected in EDA during EI, but not during ER. Lastly, compared to men, women had higher emotion rating for both fear and disgust without corresponding differences in EDA. In conclusion, in the present study we show that emotion induction was associated with differential activation in both PFC and sympathetic nerve activity for fear and disgust. These differences were however less prominent during emotion regulation. We discuss the potential interpretation of our results and their implications regarding our understanding of negative emotion processing.

Behavioral, cortical and autonomic effects of single-dose escitalopram on the induction and regulation of fear and disgust: Comparison with single-session psychological emotion regulation with reappraisal

“…Previous studies have also shown physiological differences in the autonomic responses fear and disgust elicit ( 7 , 8 , 76 , 77 ). Consistent with this, we found in a previous study ( 61 ) significant differences in EDR frequency during emotion induction of fear and disgust, reflecting increased sympathetic activity during fear but not disgust. This difference in EDR frequency between fear and disgust was replicated in the current study in the placebo arm but was abolished by escitalopram.…”

“…(A,B) The dotted line comparisons in A (fear) and B (disgust) show that compared to control phase, after ingestion of escitalopram, a roughly 30% increase in electrodermal response frequency was measured at rest (absence of emotive stimuli) during the fear experiments but not the disgust ones. (A–D) The solid line comparisons show that, similarly to what was previously reported in a study without pharmacological intervention ( 61 ), placebo was associated with no difference between task EDA and rest in fear (A,C) but lower than rest in disgust (B,D) . This pattern was reversed in the escitalopram arm, where task EDA was significantly lower than rest in fear (A,C) but not significantly different than rest in disgust (B,D) .…”

“…Direct comparison of the two negative emotions illustrates this contrast more clearly. In a previous study ( 61 ), in the absence of any pharmacological intervention, we found greater activation of right ventrolateral PFC during disgust compared to fear, an area known to be involved in response inhibition and in this case possibly reflecting a need for motor inhibition during disgust to suppress emetic impulses ( 91 , 92 ). However, in the presence of escitalopram, there was instead greater activation in bilateral lateral PFC for fear compared to disgust, with no PFC areas found to be more strongly activated during disgust compared to fear.…”

“…EDA measures changes in sympathetic nerve activity and is often used as a peripheral marker of cognitive and affective processes related to limbic and PFC activity ( 74 ). Although not specific for a given emotion by itself ( 75 ), previous studies have shown physiological differences in the responses different emotions preferentially elicit; for example, sympathetic activation for fear and parasympathetic activation for disgust ( 8 , 61 , 76 , 77 ).…”

“…Studies investigating psychological regulation of emotions have also demonstrated changes in the fronto-limbic circuits. Lateral PFC, especially dorsolateral areas, have been associated with cognitive control of behavior ( 56 – 59 ), and its activation changes in tandem with cognitive regulation of emotion with reappraisal ( 60 , 61 ). Long-term psychological treatments that promote cognitive reappraisal skills ( 3 , 62 , 63 ), and successful psychotherapy improving cognitive control have also been associated with post-treatment reduction in PFC activity ( 64 – 66 ).…”