A continuous emotional task activates the left amygdala in healthy volunteers: ¹⁸FDG PET study

Abstract 

Human amygdalar activation has been reported during facial emotion recognition (FER) studies, mostly using fast temporal resolution techniques (fMRI, H₂¹⁵O PET or MEG). The ¹⁸FDG PET technique has never been previously applied to FER studies. We decided to test whether amygdala response during FER tasks could be assessed with this technique. The study was conducted in 10 healthy right-handed volunteers who underwent two scans on different days in random order. Content of the tasks was either emotional (ET) or neutral (CT) and lasted for 17 ½ min. Three SPM2 analyses were completed. The first, an ET-CT contrast, showed left amygdalar activation. The second ruled out order effect as a confounder factor. Finally, the whole brain contrast showed activation of the emotional recognition-related areas. Time responses and errors indicated high rates of accuracy in both tasks. We discuss the results and the role of habituation phenomena and the possibility of applying this technique to samples of patients with psychiatric disorders. In conclusion, our study reveals left amygdalar activation assessed with FDG PET, as well as other major emotion recognition-related brain areas during FER tasks.

Keywords: Positron emission tomography, Nuclear medicine, Limbic system, Hemispheric specialization