Academic journal article Cognitive, Affective and Behavioral Neuroscience

Functional Brain Activation to Emotional and Nonemotional Faces in Healthy Children: Evidence for Developmentally Undifferentiated Amygdala Function during the School-Age Period

Academic journal article Cognitive, Affective and Behavioral Neuroscience

Functional Brain Activation to Emotional and Nonemotional Faces in Healthy Children: Evidence for Developmentally Undifferentiated Amygdala Function during the School-Age Period

Article excerpt

Published online: 1 May 2013

# Psychonomic Society, Inc. 2013

Abstract The amygdala is a key region in emotion processing. In particular, fMRI studies have demonstrated that the amyg- dala is active during the viewing of emotional faces. Previous research has consistently found greater amygdala responses to fearful than to neutral faces in adults, convergent with a focus in the animal literature on the amygdala's role in fear processing. Studies have shown that the amygdala also responds differen- tially to other facial emotion types in adults. Yet the literature regarding when this differential amygdala responsivity develops is limited and mixed. Thus, the goal of the present study was to examine amygdala responses to emotional and neutral faces in a relatively large sample of healthy school-age children (N =52). Although the amygdala was active in response to emotional and neutral faces, the results did not support the hypothesis that the amygdala responds differ- entially to emotional faces in 7- to 12-year-old children. Nonetheless, amygdala activity was correlated with the severity of subclinical depression symptoms and with emotional regu- lation skills. Additionally, sex differences were observed in frontal, temporal, and visual regions, as well as effects of pubertal development in visual regions. These findings suggest important differences in amygdala reactivity in childhood.

Keywords Amygdala . Childhood . Emotional processing . Face processing . fMRI

Early investigations of the amygdala's functional role in humans consistently noted that the amygdala is significantly involved in the processing of fear-related stimuli (e.g., Adolphs, Tranel, Damasio, & Damasio, 1995; Bishop, Duncan, & Lawrence, 2004;Broksetal.,1998;Calder,1996; LaBar, Gatenby, Gore, LeDoux, & Phelps, 1998; LeDoux, 2003; Morris et al., 1998; Phillips et al., 1997). More recent studies have indicated that the amygdala is responsive to other emotions, as well. For example, meta-analytic work has indicated that emotional stimuli are significantly more likely to elicit amygdala activity than are neutral stimuli, for a variety of both negative and positive emotions (e.g., fear, disgust, sadness, humor, and happiness; Costafreda, Brammer, David, & Fu, 2008). However, whereas amygdala responsivity to emotional stimuli in adults has been well studied, relatively little is known about when differential amygdala responsivity to different emotionally evocative stimuli arises during development. The existing studies in the developmental literature (looking at healthy samples or investigating healthy groups within studies of psychopathology) have provided mixed results, with some studies finding increased amygdala activity to emotional as compared to neutral faces (e.g., Britton et al., 2010; Guyer et al., 2008; Monk et al., 2003), and others failing to detect differential responses (e.g., Thomas, Drevets, Dahl, et al., 2001a; Tottenham et al., 2011; Viding et al., 2012). Many of these studies employed relatively small sample sizes across a wide age range, which may have contributed to the conflicting findings. Thus, the goal of this study was to examine whether the amygdala shows differential activity to emotional and neutral faces in a relatively large sample of healthy children between the ages of 7 and 12.

Differential amygdala responses to emotional faces in adults

There is clear evidence that the amygdala is more active in response to fearful than to neutral faces in adults (Breiter et al., 1996;Bryantetal.,2008; Pessoa, Kastner, & Ungerleider, 2002; Surguladze et al., 2003;Wrightetal.,2001), but evi- dence is mixed as to whether amygdala responses to fearful faces are stronger than its responses to other types of emotional faces. Some studies have found greater amygdala activity to fearful than to either happy (Morris et al., 1998;Whalenetal., 1998) or disgusted (Phillips et al., 2004) faces, and a meta- analysis found that amygdala activity to fear stimuli was significantly more likely than activity to sad and happy stimuli (Phan, Wager, Taylor, & Liberzon, 2002). …

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