In the first step ,we addressed for the first time the issue of the test-retest reliability of brain activation during emotion regulation by acquiring 7T fMRI data. For this, 25 participants (21 female, age: M=22.84 ± 3.27years) performed a well-established emotion regulation task during three scanning sessions separated by one week. We acquired four runs/session and 80 trials/session using the CMRR multiband EPI sequence (TR=1.4s; TE=23ms; 78 slices; voxel size=1.5x1.5x1.2mm3) at ultra-high field (7 Tesla). Specifically, we focused on the reliability of regions within four different networks shown to be involved in emotion generation and regulation that were derived from a recent meta-analysis (Morawetz et al., 2020). The effect of emotion regulation was demonstrated on the behavioral and neuronal level. First, emotion regulation was successful as indicated by high emotion regulation success across all sessions. Second, in accord with previous findings, emotion regulation compared with the control condition across all sessions was associated with increased activation in frontal (IFG, SFG, SMA), temporal (MTG) and parietal (precuneus) regions. During emotion generation, i.e. control condition vs. emotion regulation condition, activity in the frontal (IFG, SMA), the temporal (STG) and the cingulate cortex as well as the insula was enhanced, in line with previous research (Morawetz et al., 2017; Ochsner et al., 2004). With regard to test-retest reliability, our results yielded good reliability of a well-established emotion regulation task on a behavioral level. Test-retest reliability of underlying neural networks varied considerable across the networks and respective ROIs. Importantly, prefrontal and temporal regions demonstrated good to excellent test-retest reliability during the down-regulation of emotions, which implies that these regions might represent stable core regions supporting cognitive emotion regulation that can be studied on an individual subject level.
In the second step, we determined which brain regions are functionally coupled with the amygdala during emotion regulation. A myriad of neuroimaging studies has investigated the neural underpinnings of emotion regulation. However, single studies usually provide limited insight into the function of specific brain regions. Hence, to better understand the interaction between key regions involved in emotion generation and regulation, we performed a coordinate-based meta-analysis on functional magnetic resonance imaging (fMRI) studies that examined emotion regulation-modulated connectivity of the amygdala using psychophysiological interaction (PPI) analysis. We analyzed fifteen PPI studies using the activation likelihood estimation (ALE) algorithm. Overall, convergent connectivity during emotion regulation independent of regulation strategy and goal between the amygdala and the left ventrolateral prefrontal cortex (vlPFC) emerged. A more focused analysis testing for effective coupling during the down-regulation of emotions by using reappraisal specifically, revealed convergent connectivity between the amygdala and the right dorsolateral prefrontal cortex (dlPFC), the left ventrolateral prefrontal cortex (vlPFC) and the dorsomedial prefrontal cortex (dmPFC).These prefrontal regions have been implicated in emotion regulatory processes such as working memory (dlPFC), language processes (vlPFC) and the attribution of mental states (dmPFC). Our findings suggest not only a dynamic modulation of connectivity between emotion generative and regulatory systems during the cognitive control of emotions, but also highlight the robustness of task-modulated prefrontal-amygdala coupling, thereby informing neurally-derived models of emotion regulation.
