f emotional information with respect to age and sex were published in the scientific journal NeuroReport in February 2001 (Killgore, Oki and Yurgelun-Todd 2001). It was a matter of using fMRI to measure the activation of the amygdala versus that of the prefrontal cortex in young girls and young boys aged 9-17 upon viewing photographs of the facial expression of fear from Ekman and Friesen’s POFA set. The researchers believe this experimental protocol allowed them to make visible a difference in the activation of the amygdala versus that of the prefrontal cortex, partly in relation to the age and partly in relation to the sex of the participants (Killgore, Oki and Yurgelun-Todd 2001). Referring to these results and to the results of an unpublished study that evaluated the capacity of adolescents, as compared with adults, to recognize the facial affect of fear, Yurgelun-Todd said in an interview,
In general, the males in our studies showed more reaction from that gut region [the amygdala] of the brain, and less frontal or executive reaction. The relationship between the gut response and that executive region was very striking for the males, and somewhat striking for the females, but was not as extreme for the teenage females compared to the teenage males. (PBS Frontline 2002, p. 4)
Given that the adolescent state is defined by how the subjects activate the prefrontal cortex versus the amygdala, this statement suggests that adolescence is inflected in two similar versions but with different degrees of intensity depending on whether the subjects are girls or boys. By contrast, Yurgelun-Todd offers a dichotomous reading when she compares the responses of young subjects and adults, stating that,
The brain is responding differently to the outside world in teenagers compared to adults. And in particular, with emotional information, the teenager’s brain may be responding with more of a gut reaction than an executive or more thinking kind of response. And if that’s the case, then one of the things that you expect is that you’ll have more of an impulsive behavioral response, instead of a necessarily thoughtful or measured kind of response. (PBS Frontline 2002, p. 3)
Here the fMRI technique that is materialized in the scanned image, starting with photos of facial affect and using the bodies of volunteer subjects, has allowed the introduction of a dual hierarchy in the cerebral management of emotional information, first between adults and adolescents, and then between young girls and young boys.
In order to see this process of translation more clearly, let us review the description of this experiment and try to bring out all the elements involved in the trajectory from the photograph of the facial affect of fear to the production of the scanned image, of which the researchers’ reading and interpretation produces a classification as a function of the age and sex of the subjects in terms of their management of emotional information : nine boys and ten girls who have been predefined as adolescent and whose eyesight and mental health have been tested lie in a scanner and look at black-and-white photographs from the 1970s of Caucasian-type men and women performing the facial affect of fear according to the tension and muscle positioning indicators developed by Ekman and Friesen. By measuring the signal that reflects variations in the quantity of oxygen in the blood as a function of brain activity (the blood-oxygen-level-dependent or BOLD signal) during periods of visualizing photos of the facial affect of fear versus periods of visualizing a white circle, fMRI produces a statistical image by means of a system of digital computation and analysis which represents in colors a difference in the activation of the cerebral regions under study as a function of the age and sex of the individual in the scanner, cerebral regions which previous experiments on animals and humans suffering from brain lesions have established as being pertinent to the management of the emotional information of fear (Killgore, Oki and Yurgelun-Todd 2001).
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