Abstract
Objective: Stress initiates intricate changes in functional connectivity (FC) between amygdala and cortical regions that are associated with vigilance monitoring, salience processing and executive control. The functional integrity of these stress regulation circuitries can be assessed via amygdala-centered resting state functional connectivity
(rs-FC). Previous studies have associated changes in amygdala rs-FC with state, trait and pathological anxiety. Neurexan®, a medicinal product sold over the counter (OTC), is composed of passionflower, oats, coffee and zinc valerianate. A recent study suggested that Neurexan® attenuates neuroendocrine stress response in healthy
volunteers. Thus, in the present study, we aimed to explore the effect of Neurexan® on the amygdala-centered rs-FC. Methods: Thirty-nine healthy male subjects (age = 43.7 ± 9.8) participated in an fMRI study of Neurexan® effects on resting state function using a double-blind, randomized, placebo-controlled, within-subject crossover design. In each scanning session, an 11-min resting state measurement was performed at baseline and after the intake of single
dose of Neurexan® or placebo. Data were preprocessed and analyzed in SPM12 and DPABI. Using a seed-based approach, resting state functional connectivity maps of bilateral centromedial (CeA) and basolateral (BLA) subregions of amygdalawere analyzedwith whole–brain within–subject ANOVA(interaction: time by pharmaceutical,FWE cluster level
corrected). Regions were created according to the probabilistic cytoarchitectonic maps provided by the Anatomy Toolbox.
Results: Significant effect of Neurexan® was found on rs-FC between left centromedial amygdala and cortical regions including posterior cingulate cortex, dorsomedial prefrontal cortex and bilateral inferior parietal lobule. This interaction was driven by a greater reduction of the left CeA rs-FC in Neurexan® compared to control condition after
the intake of drug.
Conclusion: Our finding suggests that Neurexan® influences resting state functional connectivity of the centromedial amygdala towards cortical regions involved in emotion regulation and higher cognitive processes.
