Relationships between serotonin availability and frontolimbic response to fearful and threatening faces

Abstract

Serotonin is a critical neurotransmitter in the regulation of emotional behavior. Although emotion processing is known to engage a corticolimbic circuit, including the amygdala and prefrontal cortex, exactly how this brain system is modulated by serotonin remains unclear. Here, we hypothesized that serotonin modulates variability in excitability and functional connectivity within this circuit. We tested whether this modulation contributes to inter-individual differences in emotion processing. Using a multimodal neuroimaging approach with a simultaneous PET-3T fMRI scanner, we simultaneously acquired BOLD signal while participants viewed emotional faces depicting fear and anger, while also measuring serotonin transporter (SERT) levels, regulating serotonin functions. Individuals with higher activity of the medial amygdala BOLD in response to fearful or angry facial expressions, who were temperamentally more anxious, also exhibited lower SERT availability in the dorsal raphe nucleus (DRN). Moreover, higher connectivity of the medial amygdala with the left dorsolateral prefrontal and the anterior cingulate cortex was associated with lower levels of SERT availability in the DRN. These results demonstrate the association between the serotonin transporter level and emotion processing through changes in functional interactions between the amygdala and the prefrontal areas in healthy humans.

Mapping the evolution of neurofeedback research: a bibliometric analysis of trends and future directions

“…This cluster indicates a growing interest in studying the neural underpinnings of emotion regulation and self-regulation using advanced neuroimaging techniques such as functional Magnetic Resonance Imaging (fMRI) and real-time fMRI (Zhu et al, 2019;Mathiak and Keller, 2021;Taschereau-Dumouchel et al, 2022;Zotev et al, 2023). This cluster's connections show an interaction between brain regions, particularly the amygdala and the prefrontal cortex, in modulating emotional responses and self-regulation processes (Lowe et al, 2020;Drigas and Mitsea, 2021;Janet et al, 2023). The amygdala is well-known for its role in emotion processing, particularly fear and anxiety (Šimić et al, 2021), whereas the prefrontal cortex is associated with higher-order cognitive functions and executive control (Friedman and Robbins, 2022).…”

Advances in neural circuits of innate fear defense behavior

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