Modeling the Mental Representation of Facial Expression Using Reverse Correlation: A Study into the Role of the Basolateral Amygdala and the Sensory Regulation Function of Emotion

Abstract

Emotion is an important evolutionary adaptation, which plays a critical role in allowing humans to interact with their environment—from social communication to sensory regulation. Facial expressions are the primary mechanisms by which emotion is expressed. The understanding of how expressions are created, perceived, and processed can be explored using a psychophysical method known as reverse correlation that allows randomly generated stimuli to model the mental representations of various emotions and distinct groups. The present study uses this technique to quantify differences between populations (Experiment 1) and emotions (Experiment 2). The first experiment compared the representation of fear between healthy controls and a group of individuals with a genetic disorder called Urbach-Wiethe disease, resulting in calcifications of the basolateral amygdala (BLA) and thus heightened fear perception. The patient population’s model had darker eye regions compared to controls, suggesting increased attention to and reliance on the eyes to identify fear. This finding supports the BLA’s role in down regulation of the amygdala’s acute vigilance system. The second experiment produced one model for fear and one for disgust within a single population. Contrary to previous research which indicated that fear and disgust facial expressions are opposite in form and sensory regulation function, the two representations were much more similar than they were opposite. The positive outcome of the first experiment and unfavorable outcome of the second suggests that this particular paradigm may not be sensitive enough to pick up differences between negative emotions, while it is useful in detecting group differences.