Happiness, anger, surprise, irritation… if we note down the emotions that we go through on a given day, the list will most probably be quite long. A surge of studies on the bidirectional interaction between emotion and cognition suggests that we need emotional appraisals in order to lead a successful life and maintain our personal, social and economic integrity (Bechara, 2005; Damasio, 1994; Fox, 2008; Gross & Thompson, 2007; Walter, 2005). And yet, we seldom ‘just’ experience emotions, but often try to influence them to best fit our current goals. Based on the assumption that emotional reactions entail changes on various levels, and that these changes happen in- or outside of our awareness, affective science has adopted emotion regulation as one of its major research topics (Beauregard, Levesque, & Paquette, 2004; Gross, 1999; Ochsner, 2007). In fact, neural (e.g. amygdala activation) and behavioral (e.g. feeling of negativity) correlates of emotional reactions are effectively reduced by top-down processes of explicit and implicit control (Drabant, McRae, Manuck, Hariri, & Gross, 2009; Levesque, et al., 2003; Ochsner, Ray, et al., 2004). Furthermore, evidence from studies investigating voluntary thought control suggests that control strategies may have lasting and paradoxical consequences (Abramowitz, Tolin, & Street, 2001; Wegner, 2009). In a very recent investigation, lasting effects of regulation were also shown after the cognitive control of emotions: the activation timecourse of the amygdala was significantly increased immediately following regulation, and this difference was also related to the activation of the amygdala to the same stimuli a few minutes later (Walter, et al., 2009). Aside from these contextual or qualitative influences, emotional processing also differs between individuals: genetic variation within the serotonergic system for instance is known to affect emotional reactivity both on the behavioral and on the neural level (Hariri, et al., 2005; Hariri, et al., 2002; Lesch, et al., 1996). In the present work, the temporal dynamics of volitional emotion regulation were investigated in three studies. It was hypothesized that both the subjective experience of negativity and the amygdala activation can be attenuated by the detachment from negative emotions, which in turn leads to an immediate neural aftereffect after the offset of regulation. Furthermore, volitional emotion regulation was expected to be capable of reducing or even obliterating genetically mediated amygdala hyperreactivity to negative emotional cues. Similar to previous investigations (Walter, et al., 2009), pictures of aversive or neutral emotional content were presented while participants were instructed to react naturally to half of the pictures, and to regulate their emotional response upon the other half of the stimuli. The first two studies of the present work were designed to further characterize the immediate aftereffect of volitional regulation in the amygdala: Study 1 included behavioral ratings of negativity at picture offset and at fixation offset in order to provide behavioral measures of experiential changes, while in Study 2, participants continued to experience or regulate their emotions during a “maintain” phase after picture offset. The primary goal of Study 3 was to evaluate whether volitional emotion regulation can reduce genetically mediated amygdala hyperreactivity to aversive emotional material in individuals with the short variant of the serotonin transporter genotype (Hariri, et al., 2005; Hariri, et al., 2002), and whether the immediate aftereffect is also influenced by the serotonin transporter genotype. In all three studies, the amygdala was significantly activated by aversive versus neutral stimuli, while cognitive emotion regulation attenuated the activation in the amygdala and increased the activation in a frontal-parietal network of regulatory brain regions. This neural effect was complemented by the behavioral ratings which show that the subjective experience of negativity was also reduced by detachment (Study 1). Also in all three studies, an immediate aftereffect was observed in the amygdala following the end of regulation. Moreover, the preoccupation with the previously seen pictures after the scanning session varied across the experimental conditions (Studies 2 and 3). Volitional regulation proved effective in reducing amygdala activation to negative stimuli even in 5-HTTLPR short allele carriers that show an increased reactivity to this type of cue. At the same time, functional coupling of the ventrolateral and medial orbital prefrontal cortex, the subgenual and the rostral anterior cingulate with the amygdala was higher in the s-group. However, in Study 3 the immediate aftereffect was found only in l/l-homozygote individuals following the regulation of fear. Taken together, the results of the three studies clearly show that volitional regulation is effective in reducing behavioral and neural correlates of the experience of negative emotions (Levesque, et al., 2003; Ochsner, Bunge, Gross, & Gabrieli, 2002; Ochsner, Ray, et al., 2004), even in the case of a genetically mediated hyperreactivity to such materials. Thus, it seems reasonable to assume that conscious will can effectively counteract genetic determinants of emotional behavior. Moreover, the present results suggest that the temporal dynamics of volitional emotion regulation are characterized by a paradoxical rebound in amygdala activation after regulation, and that the immediate aftereffect is a marker of the efficiency of the initial and the sustained effects of emotion regulation (Walter, et al., 2009). In summary, the successful replication of the immediate aftereffect of emotion regulation in all three studies of this dissertation opens up exciting new research perspectives: a comparison of the short- and long-term effects of different regulatory strategies, and the investigation of these effects also in positive emotions would complement the present results, since the neural mechanisms involved in these processes show some characteristic differences (Ochsner, 2007; Staudinger, Erk, Abler, & Walter, 2009). A comprehensive characterization of this neural marker and its implications for emotional experience might also be useful with respect to clinical applications. The detailed examination of the various time scales of emotional regulation might for instance inform the diagnostic and therapeutic interventions in affective disorders that are associated with emotional dysfunctions (Brewin, Andrews, & Rose, 2000; Johnstone, van Reekum, Urry, Kalin, & Davidson, 2007). Ultimately, we might thus come to understand the neural underpinnings of what the feelings we have today have to do with the feelings we had yesterday – and with the feelings with might have tomorrow.

Happiness, anger, surprise, irritation… if we note down the emotions that we go through on a given day, the list will most probably be quite long. A surge of studies on the bidirectional interaction between emotion and cognition suggests that we need emotional appraisals in order to lead a successful life and maintain our personal, social and economic integrity (Bechara, 2005; Damasio, 1994; Fox, 2008; Gross & Thompson, 2007; Walter, 2005). And yet, we seldom ‘just’ experience emotions, but often try to influence them to best fit our current goals. Based on the assumption that emotional reactions entail changes on various levels, and that these changes happen in- or outside of our awareness, affective science has adopted emotion regulation as one of its major research topics (Beauregard, Levesque, & Paquette, 2004; Gross, 1999; Ochsner, 2007). In fact, neural (e.g. amygdala activation) and behavioral (e.g. feeling of negativity) correlates of emotional reactions are effectively reduced by top-down processes of explicit and implicit control (Drabant, McRae, Manuck, Hariri, & Gross, 2009; Levesque, et al., 2003; Ochsner, Ray, et al., 2004). Furthermore, evidence from studies investigating voluntary thought control suggests that control strategies may have lasting and paradoxical consequences (Abramowitz, Tolin, & Street, 2001; Wegner, 2009). In a very recent investigation, lasting effects of regulation were also shown after the cognitive control of emotions: the activation timecourse of the amygdala was significantly increased immediately following regulation, and this difference was also related to the activation of the amygdala to the same stimuli a few minutes later (Walter, et al., 2009). Aside from these contextual or qualitative influences, emotional processing also differs between individuals: genetic variation within the serotonergic system for instance is known to affect emotional reactivity both on the behavioral and on the neural level (Hariri, et al., 2005; Hariri, et al., 2002; Lesch, et al., 1996). In the present work, the temporal dynamics of volitional emotion regulation were investigated in three studies. It was hypothesized that both the subjective experience of negativity and the amygdala activation can be attenuated by the detachment from negative emotions, which in turn leads to an immediate neural aftereffect after the offset of regulation. Furthermore, volitional emotion regulation was expected to be capable of reducing or even obliterating genetically mediated amygdala hyperreactivity to negative emotional cues. Similar to previous investigations (Walter, et al., 2009), pictures of aversive or neutral emotional content were presented while participants were instructed to react naturally to half of the pictures, and to regulate their emotional response upon the other half of the stimuli. The first two studies of the present work were designed to further characterize the immediate aftereffect of volitional regulation in the amygdala: Study 1 included behavioral ratings of negativity at picture offset and at fixation offset in order to provide behavioral measures of experiential changes, while in Study 2, participants continued to experience or regulate their emotions during a “maintain” phase after picture offset. The primary goal of Study 3 was to evaluate whether volitional emotion regulation can reduce genetically mediated amygdala hyperreactivity to aversive emotional material in individuals with the short variant of the serotonin transporter genotype (Hariri, et al., 2005; Hariri, et al., 2002), and whether the immediate aftereffect is also influenced by the serotonin transporter genotype. In all three studies, the amygdala was significantly activated by aversive versus neutral stimuli, while cognitive emotion regulation attenuated the activation in the amygdala and increased the activation in a frontal-parietal network of regulatory brain regions. This neural effect was complemented by the behavioral ratings which show that the subjective experience of negativity was also reduced by detachment (Study 1). Also in all three studies, an immediate aftereffect was observed in the amygdala following the end of regulation. Moreover, the preoccupation with the previously seen pictures after the scanning session varied across the experimental conditions (Studies 2 and 3). Volitional regulation proved effective in reducing amygdala activation to negative stimuli even in 5-HTTLPR short allele carriers that show an increased reactivity to this type of cue. At the same time, functional coupling of the ventrolateral and medial orbital prefrontal cortex, the subgenual and the rostral anterior cingulate with the amygdala was higher in the s-group. However, in Study 3 the immediate aftereffect was found only in l/l-homozygote individuals following the regulation of fear. Taken together, the results of the three studies clearly show that volitional regulation is effective in reducing behavioral and neural correlates of the experience of negative emotions (Levesque, et al., 2003; Ochsner, Bunge, Gross, & Gabrieli, 2002; Ochsner, Ray, et al., 2004), even in the case of a genetically mediated hyperreactivity to such materials. Thus, it seems reasonable to assume that conscious will can effectively counteract genetic determinants of emotional behavior. Moreover, the present results suggest that the temporal dynamics of volitional emotion regulation are characterized by a paradoxical rebound in amygdala activation after regulation, and that the immediate aftereffect is a marker of the efficiency of the initial and the sustained effects of emotion regulation (Walter, et al., 2009). In summary, the successful replication of the immediate aftereffect of emotion regulation in all three studies of this dissertation opens up exciting new research perspectives: a comparison of the short- and long-term effects of different regulatory strategies, and the investigation of these effects also in positive emotions would complement the present results, since the neural mechanisms involved in these processes show some characteristic differences (Ochsner, 2007; Staudinger, Erk, Abler, & Walter, 2009). A comprehensive characterization of this neural marker and its implications for emotional experience might also be useful with respect to clinical applications. The detailed examination of the various time scales of emotional regulation might for instance inform the diagnostic and therapeutic interventions in affective disorders that are associated with emotional dysfunctions (Brewin, Andrews, & Rose, 2000; Johnstone, van Reekum, Urry, Kalin, & Davidson, 2007). Ultimately, we might thus come to understand the neural underpinnings of what the feelings we have today have to do with the feelings we had yesterday – and with the feelings with might have tomorrow.