Abstract:

Arousal is an activator for the body's resources, reflecting the strengthened preparation for external stimulus input. As it is introduced into the emotional dimension, arousal is regarded as one of the core characteristics of emotions, which is a measurement of body's wakefulness, and its level changes on the continuum from sleep to provocation. Arousal can be subjectively experienced by individuals, and has a unique physiological mechanism and neural circuit. Its concept contains both psychological arousal and physical arousal. However, as arousal is closely related to emotions, many investigators neglect the original meaning of arousal, taking arousal as a substitute for emotional intensity. The reason for this confusion may be that valence is regarded as the direction of emotions. In fact, valence is only a feature of emotions. It also has different intensities, which affect the emotional intensity. Therefore, arousal cannot be simply equaled with emotional intensity. Instead, emotional intensity should be the vector addition of arousal and valence.

In this paper, we analyze the concept of arousal and its relationship with emotions. Then, inspired by Lazarus' argument that stimuli define emotions, we hold that it may be possible to further understand the connotation and psychological mechanism of arousal from the perspective of anticipation. Specifically, a variety of emotions can be summed up to an objective material or stimulus. In other words, it is stimuli that define emotions; when stimuli appear more unexpectedly, it indicates that the level of previous preparedness is lower, so more resources are needed for the individual to mobilize, and the level of arousal rises in response. Anticipation and its related mechanisms (uncertainty, habitation, etc.) are the major cognitive mechanisms of arousal. As for other factors (stimulus attributes, individual differences, etc.), as the number of resources that the individual needs to process the stimulus changes, the one of the resources required to be mobilized after the stimulus appears(arousal level) changes accordingly. Besides, the degree of individual expectations can be affected. As a result, these factors also affect the level of arousal.

The neural mechanism of arousal mainly involves a “bottom-up” pathway that originates from the brainstem and projects to the thalamus, hypothalamus, and cerebral cortex. The arousal signals in the brainstem and the tail of the hypothalamus mainly come from the areas rich in monoamine neurons and cholinergic neurons. The GABAergic neurons in the preoptic area of ??the hypothalamus, the lateral hypothalamus, and the sub-substantia nigra reticular region play a role in inhibiting arousal. Some key cortical nodes in the default mode network and the salience network and their interconnections also participate in the processing of arousal levels. It is worth noting that the arousal system almost overlaps with the brain area that encodes unexpected signals. Based on this, the anticipatory mechanism is presumably the key factor that induces arousal changes.

This paper suggests that future researchers may further promote the basic and applied research for arousal from the following aspects: FMRI, eye movement, skin conductance and other technical methods may be used to explore the effect of physical arousal on psychological arousal, which is helpful to further clarify the physiological basis of arousal and related processing mechanisms; a model of integrating multimodal data may be used to optimize the measurement of arousal; the arousal characteristics of human mental diseases (especially comorbid problems) may be further evaluated; and it would be better if the discussion of the relationship between arousal and emotional intensity be more in-depth.

Key words: arousal, anticipation, cognitive mechanism, sleep, wakefulness, emotional intensity