Amygdala activity to fear and anger in healthy young males is associated with testosterone

Neuroimaging studies have documented modulation of the activity of the amygdala - a key node in the neural network underlying emotion perception and processing, and one that has also been associated with regulating aggression - by exogenous testosterone. However, results on the impact of normal range testosterone levels on explicit emotion recognition as a prerequisite for social interaction and amygdala activation in healthy young males are missing. Hence, we performed functional MRI at 3T in a group of 21 healthy males during explicit emotion recognition with a protocol specifically optimized to reliably detect amygdala activation. We observed similar amygdala activation to all emotions presented without any effect of gender of poser or laterality. Reaction times to fearful male faces were found negatively correlated to testosterone concentration, while no significant effects emerged for other emotions and neutral expressions. Correlation analyses revealed a significant positive association between testosterone levels and amygdala response to fearful and angry facial expressions, but not to other expressions. Hence, our results demonstrate that testosterone levels affect amygdala activation and also behavioral responses particularly to threat-related emotions in healthy young males. We conclude that these findings add to our understanding of emotion processing and its modulation by neuroendocrine factors.