Features of connectivity of default mode network depending on polymorphism of serotonin transporter gene (5-HTTLPR)

Serotonin transporter gene polymorphism is important in the regulation of the serotoninergic system that affects mood and the regulation of emotions and behavior. In this study, 128 channel electroencephalogram recordings were performed, and buccal epithelium samples were obtained from 53 volunteers (32 females). La, Lg, and S alleles were identified by polymerase chain reaction. The aim of the study was to investigate the connectivity of the default mode network, measured using resting state electrophysiologic data, depending on the serotonin transporter gene polymorphism. Localization of the sources of bioelectrical activity of the cerebral cortex was performed by the beamformer method. Comparisons of LaLa genotype carriers and S or Lg allele carriers were performed using T-contrast of connectivity indices calculated between the nodes of the default mode network and the rest of the brain. It was found that carriers of the S allele were characterized by increased connectivity of the default mode network with the visual association cortex and with structures forming the posterior node of the default mode network, as well as increased connectivity of the posterior node of the default mode network with the right parahippocampal gyrus, and this pattern of connectivity may predispose to the onset and/or maintenance of intrusive thoughts. Whereas carriers of the LaLa genotype had higher connectivity of the anterior node of the default mode network with the right ventromedial prefrontal cortex, with the medial frontal gyrus, and with the posterior cingulate cortex, which is the structure of the posterior node of the default mode network, compared to carriers of the S or Lg allele. Also, carriers of the LaLa genotype had higher connectivity of the posterior node of the default mode network with the cluster involving the right dorsolateral prefrontal cortex compared to carriers of the S or Lg allele. It could be hypothesized that increased connectivity of the default mode network with brain structures (i. e., dorsolateral and ventromedial prefrontal cortex) involved in cognitive regulation processes may contribute to the regulation of the processes of the default mode network associated with autobiographical memory.