The Authors: The article entitled “Cultural Specificity in Amygdala Response to Fear Faces” was researched by Joan Y. Chiao, Tetsuya Iidaka, Heather L. Gordon, Junpei Nogawa, Moshe Bar, Elissa Aminoff, Norihiro Sadato, and Nalini Ambady. All of these researchers sought to study the amygdala and whether cultural specificity had an affect on the neural response to fear faces.
Intro: The human amygdala is greatly activated to fear faces. It is thought that this heightened response is a reflection of an adaptive social signal to either warn or solicit help from others. Prior neuroimaging studies have only examined amygdala response to different emotional stimuli in participants within the same culture and not cross culturally, it remains unknown whether culture affects the neural response to fear faces. The researchers’ decided to test their hypotheses on two distinct cultures, native Japanese in Japan and Caucasians in the United States.
Hypotheses: The authors had came up with two hypotheses for this research.
H1: Given automatic, prepotent nature of amygdala response to fear faces and the adaptive importance of responding to any signal of imminent danger in the environment, cultural affiliation will not affect the amygdala response to fear faces.
H2: Amygdala response may be enhanced for own- culture fear faces, given the greater similarity between self and other members of the same cultural group.
The purpose of the present work was to investigate these two competing hypotheses regarding culture and neural activation in response to fear faces. The researchers used event-related functional magnetic resonance imaging in two distinct cultures to investigate cultural specificity in the amygdala’s response. In total the experiment had 20 healthy participants both men and women between the ages of 18-25 years, with corrected- to-normal vision, that were right- handed. The experiment used digitized grayscale pictures of 80 faces each with either a fearful, a neutral, a happy, or an angry expression taken from Japanese and Caucasian posers (20 men and 20 women from each cultural group). All participants were tested within their own culture by an experimenter who conducted the study in their native language, for each trial participants made an emotion categorization judgment using one of four buttons, the order of the stimuli was randomized within and between functional runs.
The fMRI results were evaluated in two different ways, through actual activation of the amygdala and response time/accuracy of emotions. Consistent with the researcher’s hypotheses, whole brain analyses revealed greater activation within regions of left and right amygdala for own culture compared to other-culture fear faces. Greater response to own-culture fear faces was also found in medial-temporal regions critical to successful encoding and retrieval of faces. The study showed that Caucasian participants were significantly more accurate at recognizing fear in their own-culture relative to other culture faces, while Japanese participants were faster in recognizing fear relative to Caucasian participants. To examine whether a culture of participant and a culture of face was present at higher thresholds, anatomical ROI analyses were also conducted. The anatomical ROI analyses also confirmed that amygdala response for recognizing fear was significantly greater for member’s of one’s own culture compared to other cultural groups. No other significant response for other emotional expressions were found in the ROI analyses.
In sum, the study demonstrates that cultural specificity ( or membership) modulates the brain’s primary response to fear. This is significant because the previously demonstration of the automatic, prepotent nature of the amygdala responses to fear faces underscores the significance of further cross-cultural testing at the neural level.