27 Neuroendocrinological aspects of social anxiety and aggression related disorders al., 2007; Roelofs, Minelli, et al., 2009; Inge Volman, Toni, et al., 2011). Social AATs using emotional faces have therefore been used to objectively measure the motor responses that are brought about by the automatic and instrumentally driven tendency to approach or avoid a certain stimulus (Chen & Bargh, 1999; Heuer et al., 2007; Roelofs, Elzinga, & Rotteveel, 2005; Rotteveel & Phaf, 2004). A commonly used type is a manual reaction time task which requires participants to approach and to avoid socially appetitive and aversive visually presented stimuli (happy and angry faces, respectively) by pulling (approach) or pushing away a joystick (avoidance) (see Figure 2.2E). In zooming versions of the AAT, pulling or pushing the joystick increases or decreases the size of the picture respectively, giving the impression of moving towards or moving away from the participant (Heuer et al., 2007). Affect–behavior congruence (i.e., approaching happy or avoiding angry faces) leads to quicker responses than when automatic tendencies need to be overridden, as is the case with affect–behavior incongruence (i.e., approaching angry or avoiding happy faces). Highly socially anxious individuals have been shown to avoid socially threatening (i.e., angry) faces, compared to low anxious controls (Heuer et al., 2007; Roelofs, Putman, et al., 2010), while psychopathic offenders show diminished avoidance tendencies of angry faces, compared to controls (von Borries et al., 2012). Neurobiology underlying social motivational behavior Approach and avoidance-related behaviors are mediated by complex interacting neural networks, which can be categorized in the so-called emotional network, reward network, and cognitive control network (Cremers & Roelofs, 2016), which will be broadly described hereafter. The amygdala plays a central role in the emotional network; its subnuclei process salient information from the environment, such as emotional facial expressions, and trigger behavioral responses in response to these environmental stimuli. The basolateral amygdala (BLA) receives input from the thalamus and sensory cortices (such as fusiform gyrus, involved in face processing), whereas the central amygdala (CeA) orchestrates autonomic responses by projections to the periaqueductal gray (PAG) initiating freeze, to brainstem nuclei for release of neurotransmitters, and the hypothalamus for release of oxytocin, corticotropin releasing hormone (CRH), and gonadotropin releasing hormone (GnRH). This eventually leads to enhanced cortisol and testosterone levels, respectively. The amygdala is also connected to the reward network, which comprises the ventral tegmental area (VTA), striatum (including the nucleus accumbens (NAcc)), and medial prefrontal cortex (mPFC) (Haber & Knutson, 2010). Striatal dopamine transmission is essential for the adaptive regulation of social behavior as it is involved in reward learning 2
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