 already developing by the beginning of the second decade under the effect of pubertal hormones, while the latter, devoted to control of the emotions and long-term planning, does not reach full maturity until the age of 25 (Casey et al. 2008, Ernst and Mueller 2008). This cerebral configuration favors impulsive behaviors regulated by emotional reactions rather than by rational reasoning, which suggests a neurodevelopmental explanation for statistics on so-called risk behaviors during adolescence, for example, drunk driving, unprotected sex, fighting, consumption of psychoactive substances, etc. These behaviors, which have become the focus of major social and political concern, were seen in the United States to be responsible for a 200 % increase in morbidity and mortality during this phase of life (Dahl 2004). Statistics also show that such behaviors concern boys more than girls and that, taking all types of risk behavior into account, boys are three times more likely than girls to die as a result of this kind of situation (Kelley et al. 2004, Eaton et al. 2006). According to a neurodevelopmental logic, it is therefore important in fMRI verification to evaluate the treatment of emotional information not only from the perspective of age but also from that of sex.
My purpose here is not to present an exhaustive review of the various neuroscientific studies of the emotions whose experimental protocol is based on photographs of facial affect, but by developing an example that is pertinent from the perspective of its importance in the field, to question the process of translation between the stimulus photographs and the images produced by fMRI, as well as its productivity in constructing knowledge about adolescents’ management of emotional information. That is why I shall focus on the work of Yurgelun-Todd’s research team which has become a touchstone for this topic in science as well as in the media (cf. PBS Frontline 2002, Wallis, Dell and Park 2004, Sender 2008).
The team’s first results concerning the management of 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 y