Research Article Brain Networks Connectivity in Mild to Moderate Depression: Resting State fMRI Study with Implications to Nonpharmacological Treatment Dmitry D. Bezmaternykh , 1 Mikhail Ye. Melnikov , 1 Andrey A. Savelov , 2 Lyudmila I. Kozlova , 1 Evgeniy D. Petrovskiy , 2 Kira A. Natarova , 3 and Mark B. Shtark 1 1 Laboratory of Biofeedback Computer Systems, Institute of Molecular Biology and Biophysics, Federal Research Center of Fundamental and Translational Medicine, Novosibirsk 630060, Russia 2 International Tomography Center SB RAS, Novosibirsk 630090, Russia 3 International Institute of Psychology and Psychotherapy, Novosibirsk 630007, Russia Correspondence should be addressed to Mikhail Ye. Melnikov; mikhail-melnikov@mail.ru Received 11 July 2020; Revised 4 December 2020; Accepted 21 December 2020; Published 15 January 2021 Academic Editor: Bingjin Li Copyright © 2021 Dmitry D. Bezmaternykh et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Network mechanisms of depression development and especially of improvement from nonpharmacological treatment remain understudied. The current study is aimed at examining brain networks functional connectivity in depressed patients and its dynamics in nonpharmacological treatment. Resting state fMRI data of 21 healthy adults and 51 patients with mild or moderate depression were analyzed with spatial independent component analysis; then, correlations between time series of the components were calculated and compared between-group (study 1). Baseline and repeated-measure data of 14 treated (psychotherapy or fMRI neurofeedback) and 15 untreated depressed participants were similarly analyzed and correlated with changes in depression scores (study 2). Aside from diverse findings, studies 1 and 2 both revealed changes in within-default mode network (DMN) and DMN to executive control network (ECN) connections. Connectivity in one pair, initially lower in depression, decreased in no treatment group and was inversely correlated with Montgomery-Asberg depression score change in treatment group. Weak baseline connectivity in this pair also predicted improvement on Montgomery-Asberg scale in both treatment and no treatment groups. Coupling of another pair, initially stronger in depression, increased in therapy though was unrelated to improvement. The results demonstrate possible role of within-DMN and DMN-ECN functional connectivity in depression treatment and suggest that neural mechanisms of nonpharmacological treatment action may be unrelated to normalization of initially disrupted connectivity. 1. Introduction Depression is a widespread psychiatric disorder associated with a number of different symptoms. The diversity of symp- toms implies existence of multiple disruptions of neural cir- cuits in depression, and this may be the reason for diverse findings in studies of brain networks in depression. A body of research considers default mode network (DMN) as a central one for depression development. Depres- sion is mostly associated with increased functional connec- tivity (FC) within DMN [1–9] with a few contradicting findings [1, 10–13]. External FC of the DMN is increased to anterior cingulate [1, 14–15], thalamus [14], and pars trian- gularis [3] and decreased to fusiform gyrus, motor cortices [16], cerebellum, insula [17], thalamus, putamen, and calcar- ine sulcus [18] with mixed findings for hippocampus [1, 18– 19]. On internetwork level, depression is associated with less coupling of DMN and anterior salience network (ASN) [2] Hindawi Neural Plasticity Volume 2021, Article ID 8846097, 15 pages https://doi.org/10.1155/2021/8846097