Connectomic signatures of working memory deficits in depression, mania, and euthymic states of bipolar disorder

Decreased integration of the frontoparietal network during a working memory task in major depressive disorder

“…This study denotes a diminished global efficiency of the FPN in patients with MDD, but no whole-brain topology alteration was observed. Prior studies have suggested that WM deficits are common to affective and psychotic illnesses (Lewandowski et al, 2014), and we have reported altered whole-brain topology in schizophrenia and bipolar depression during WM processing in our prior work (Yang et al, 2020a, 2020b). The absence of the whole-brain connectomic deficits in MDD during task performance may underlie the smaller effect sizes of WM impairments in MDD compared with the other two mental disorders.…”

“…In the construction process of functional connection matrix, we only concatenated the 80 fMRI volumes obtained under the four blocks of 2-back performance (He et al, 2012) in line with our prior works (Yang et al, 2020a, 2020b), for the 0-back is not considered to be a real WM task. The mean time series was extracted from each of the 264 nodes using 6 mm spheres defined by the Power atlas (Power et al, 2011).…”

“…Nevertheless, the functional connectome topology has been acknowledged to be critical for understanding clinical symptoms (Gong and He, 2015), on one hand, and cognitive impairment (Sheffield et al, 2017), on the other, as system-level disruptions are more sensitive markers of emergent functions such as cognition and behavior (Bullmore and Sporns, 2012). We have previously employed graph theory and reported a mechanistic link between connectome topology and impaired n-back performance in schizophrenia and bipolar disorder (Yang et al, 2020a, 2020b), and further found the moderating effect of connectome properties on the relationship between clinical symptoms and WM performance. In fact, irrespective of the diagnosis, the severity of certain psychiatric symptoms such as lack of motivation, apathy and anhedonia (negative symptoms as determined by Brief Psychiatric Rating Scale [BPRS]) relates to cognitive dysfunction (Zhu et al, 2019).…”

Serotonin–norepinephrine reuptake inhibitor antidepressant effects on regional connectivity of the thalamus in persistent depressive disorder: evidence from two randomized, double-blind, placebo-controlled clinical trials

“…Network measures at each density (sparsity) were calculated on the 264×264 weighted adjacency matrices, which were acquired by thresholding the symmetric matrices at a series of network densities, ranging from top 10 to 50% of all connections, with 2% increments, in line with our prior studies. 27 , 29 The reason for choosing this density range is that network measures are less prone to non-biological artefacts and noise in this density range. 30 Negative correlations were set to zero, in line with other studies of functional connectome construction.…”

Differential Dynamical Pattern of Regional Homogeneity in Bipolar and Unipolar Depression: A Preliminary Resting-State fMRI Study

“…Nuisance covariates including 12 head motion parameters (6 head motions and their temporal first derivatives), global mean signals, white matter, and cerebrospinal fluid (CSF) signals were regressed out from the blood oxygen level-dependent (BOLD) signals. In line with our prior study, displaced volumes (framewise displacement > 0.5 mm) were interpolated by nearest-neighbor interpolation ( 29 ). The exclusion criteria for sample selection included: (1) Head motions larger than a 2.5-mm translation or 2.5° rotation in any direction; (2) More than 48 volumes were scrubbed (i.e., >20% of the acquired analysis); (3) Functional MRI (fMRI) data failed to normalize to MNI space which is visually inspected by an experienced data analyst.…”