At a functional level, the stimulus-specific laterality of these responses reflects the inherent nature and value of these stimulus types. The right biased response to faces is consistent with studies implicating right hemisphere brain regions in general, and the right amygdala specifically, for processing facial expressions, especially those of negative affect (Ahern et al 1991; Adolphs et al 2001). Furthermore, Hariri et al (2002) found that dextroamphetamine, a nonspecific monoaminergic agonist and anxiogenic, selectively potentiates the response of only the right amygdala during the perceptual processing of angry and fearful faces, suggesting that this structure may be especially critical in processing the emotional content of stimuli. In addition, human subjects who were exposed to erotic stimuli had increased levels of activation of the right amygdala and right temporal pole as measured by fMRI (Beauregard et al 2001). The right amygdala has also been shown to be associated with enhanced recall memory for emotional films (Cahill et al 2000). Finally, recent studies have demonstrated the involvement of the right amygdala in contextual conditioned fear and in stress or emotional related processes (Anderson and Teicher 1999; Baker and Kim 2004; Scicli et al 2004).
