An Integrative Way for Studying Neural Basis of Basic Emotions With fMRI

Abstract

How emotions are represented in the nervous system is a crucial unsolved problem in the affective neuroscience. Many studies are striving to find the localization of basic emotions in the brain but failed. Thus, many psychologists suspect the specific neural loci for basic emotions, but instead, some proposed that there are specific neural structures for the core affects, such as arousal and hedonic value. The reason for this widespread difference might be that basic emotions used previously can be further divided into more "basic" emotions. Here we review brain imaging data and neuropsychological data, and try to address this question with an integrative model. In this model, we argue that basic emotions are not contrary to the dimensional studies of emotions (core affects). We propose that basic emotion should locate on the axis in the dimensions of emotion, and only represent one typical core affect (arousal or valence). Therefore, we propose four basic emotions: joy-on positive axis of hedonic dimension, sadness-on negative axis of hedonic dimension, fear, and anger-on the top of vertical dimensions. This new model about basic emotions and construction model of emotions is promising to improve and reformulate neurobiological models of basic emotions.

Keywords: basic emotions; core affects; dimensional studies; fMRI; monoamine.

FIGURE 1

Basic emotion and circumplex. (A) Schlosberg proposed two-dimension of facial expression in a roughly circular surface, whose axes are pleasantness–unpleasantness and attention–rejection. The four basic emotions have different levels of activation, for example, fear and anger can reach higher levels of activation. (B) Circumplex model of emotion proposed that all emotions locate specially on a circle of the circumplex, means that different emotions have different arousal or hedonic parameters. Two core affects of emotions, which are represented on the horizontal dimension and vertical dimension, are induced by two features of a stimulus: the safety value of the stimulus and the hedonic value of the stimulus.

FIGURE 2

Integrative model for basic emotions and construction approach (dimension theory). Integrative model of emotion proposed that the basic emotions are on the specific locations in the circle of the circumplex; and they are typical emotions which have only one features of core affects: Fear and anger are only related to the safety value of the stimulus, while sadness and joy are only related to the hedonic value of a stimulus; or the “basic emotion” fear and anger have no hedonic value and happiness and sadness have no safety value (Zheng et al., 2016).

FIGURE 3

Two dimensions of emotion reflect the directions of behaviors or agitation of autonomous nervous system. The horizontal dimension represents the direction of the behavior, including the approaching/avoidance of the behavior. The emotion happiness and sadness and their behaviors prey or fleeing are on the opposite directions, happiness or joy induce approaching behavior, and sadness and disgust induce avoidance behavior. The vertical dimension represents the energy of the action (agitated or rest). Fear and anger or fight or flight might have same level of agitation, but they are twin emotions, standing back-to-back on the top of vertical axis, facing opposite direction (approaching or avoidance). The zero point of the vertical dimension means normal waking state, and negative axis means sleepy or tired, or the vertical dimensions above zero means sympathetic nervous system, and the dimensions below zero means para-sympathetic nervous system.

FIGURE 4

Fear and anger are twin emotions. At a surprise or uncertain situation, we humans usually have a safety check with the situation, which is unconscious, similar to Lazarus’s primary appraisal. Then the individual will consciously compare the situation with his own ability to see if he can cope with the situation. If the individual feels he has insufficient resources, he would flight away; or he will be angry and fight. Fear and anger occur in a tandem, with fear occurring first, then anger coming immediately afterward. Afterward, the individual will reflect upon the situation, which might be called reappraisal. If he coped successfully with the situation, he will be happy; or he will be sad. Therefore, we humans have four basic emotions. Just like Izard proposed: people need the emotion fear to explain flight for safety; anger to explain tendency to cope with the unexpected situation; joy or happiness to express the pride of achievement, and sadness to express the acceptance of failure (Izard, 2007).