Amygdala and Fear: Locationist or Social Constructivism?

The amygdala is activated for a range of positive and negative emotions, and thus the view that the amygdala controls only our fear experience would be naïve. It may be that the amygdala draws our attention to emotional events to help us encode and learn from these experiences. Vytal and Hamann (2010) conducted a meta-analysis on 83 neuroimaging studies that elicited five emotions (fear, anger, disgust, sadness, happiness) using a variety of methods (e.g., photos, facial expressions, induction). These studies looked for two types of patterns:

1) Consistency Patterns: Across studies, what are the brain regions whose activity was most consistently and strongly associated with each basic emotion?

2) Discriminable Patterns: : Across studies, is each basic emotion associated with some unique regional activations, not shared by other emotions?

Across studies, fear consistently activated three structures: both amygdalae, the right cerebellum, and the right insula (see Figure 17).

Discriminable Patterns for fear are shown in Table 7. These findings indicate that compared to most emotions, fear resulted in more activation of the amygdalae, particularly the left amygdala. The left putamen seems to also be an important structure, distinguishing fear from both anger and disgust. Another meta-analysis also identified the amygdala as uniquely activated during fear, and found that the anterior cingulate cortex (ACC) and orbito-frontal cortex (OFC) was often activated during fear as well (Murphy et al., 2003)

Note: BA = Brodmann’s Area; IFG = Interior Frontal Gyrus. Adapted from “Neuroimaging support for discrete neural correlates of basic emotions: a voxel-based meta-analysis,” by K. Vytal and S. Hamann, 2010, . Journal of Cognitive Neuroscience, 22(12), p. 2872 – 2874 (Neuroimaging Support for Discrete Neural Correlates of Basic Emotions: A Voxel-based Meta-analysis ). Copyright 2012 by Massachusetts Institute of Technology.

Discriminable and consistency patterns support the locationist view of the brain. Specifically, locationist theories support the fear-amygdala hypothesis which suggests that the amygdala is the main center of the brain involved in the fear emotion. Similar meta-analysis work by Lindquist, Barrett, and colleagues (2012) has found support against the locationist view and for the social constructivist view. When comparing emotions, they found that activation of both amygdalae was associated with fear perception and disgust experience, but not the fear experience. This means the amygdala was activated when people perceived fear in their environment such as in a fearful facial expression, but also when people viewed something disgusting, such as gore. These findings suggest the amygdala is activated for visual stimuli that result in perceiving fear or in actually feeling disgust. Further, activation in the left amygdala was greatest for sadness perception compared to other emotions (such as in viewing a sad facial expression). Their work found the right amygdala was associated with perceiving or experiencing highly arousing negative emotions like disgust, fear, and anger. Conversely, the left amygdala was activated when participants were introspecting about their emotional state, such as when recalling a fear experience. Thus, this theory suggests that the right and left amygdala serve different emotional functions, not necessarily that the amygdala is only responsible for feeling or experiencing the emotion fear.