The role of specific facial features in eliciting emotion-related amygdala activity in children: An investigation utilizing behavioral, genetic, and functional magnetic resonance imaging measures

Existing animal and adult human literature has specified a critical role for the amygdala in the processing of facial expressions. However, there is a paucity of research addressing the development of the ability to recognize and interpret face emotion. Based on extant neuroimaging work addressing the putative, fast amygdala pathway and evidence that this sub-cortical route is activated not only by the eye components of an emotional face (e.g. Morris et al., 2002) but also low-level perceptual features (Whalen et al., 2004), the core goal of this thesis is to investigate the role of individual features of faces in the amygdala response to facial emotion, as well as to better understand the role of features in children's identification of face emotion.;The current thesis utilized three measurement techniques and several behavioral manipulations designed to address questions related to the importance of specific facial features and their context in eliciting emotion-related amygdala activity in children. Chapter 2 describes forced-choice picture sorting tasks used to examine how 8-year-old children categorize emotional faces when only some of the facial features are available. Chapters 3, 4 and 5 report on three fMRI studies that examined children's brain response to low-level perceptual information in facial expressions, during an emotional-face matching task designed to activate the amygdala, and to atypical face stimuli such as inverted faces. A sub-set of participants were genotyped for the 5-HTTLPR polymorphism to explore individual differences in amygdala response during the emotional face-matching task. Chapter 6 synthesizes these four studies and discusses their contributions to the burgeoning body of knowledge on the development of face emotion processing.