Author: Kazemi R1,2, Rostami R3, Khomami S1, Baghdadi G4, Rezaei M5, Hata M6, Aoki Y6, Ishii R6, Iwase M6, Fitzgerald PB7
Affiliation: <sup>1</sup>Cognitive Lab, Department of Psychology, University of Tehran, Tehran, Iran.
<sup>2</sup>Atieh Clinical Neuroscience Center, Tehran, Iran.
<sup>3</sup>Department of Psychology, University of Tehran, Tehran, Iran.
<sup>4</sup>Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran.
<sup>5</sup>Behavioral Sciences Research Center, Life Style Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran.
<sup>6</sup>Department of Psychiatry, Graduate School of Medicine, Osaka University, Osaka, Japan.
<sup>7</sup>Epworth Healthcare, Epworth Clinic Camberwell, Victoria Australia and Monash Alfred Psychiatry Research Centre, Central Clinical School, Monash University, Melbourne, VIC, Australia.
Conference/Journal: Front Hum Neurosci.
Date published: 2018 Sep 5
Other:
Volume ID: 12 , Pages: 356 , Special Notes: doi: 10.3389/fnhum.2018.00356. eCollection 2018. , Word Count: 321
Introduction: Bipolar patients have abnormalities in cognitive functions and emotional processing. Two resting state networks (RSNs), the default mode network (DMN) and the sensorimotor network (SMN), play a decisive role in these two functions. Dorsolateral prefrontal cortex (DLPFC) is one of the main areas in the central executive network (CEN), which is linked to the activities of each of the two networks. Studies have found DLPFC abnormalities in both hemispheres of patients with bipolar depression. We hypothesized that the bilateral repetitive transcranial magnetic stimulation (rTMS) of DLPFC would produce changes in the activity of both the SMN and DMN as well as relevant cognitive function in patients with bipolar depression that responded to treatment. Methods: 20 patients with bipolar depression underwent 10 sessions of 1 Hz rTMS on right DLPFC with subsequent 10 Hz rTMS on left DLPFC. Changes in electroencephalography resting networks between pre and post rTMS were evaluated utilizing low-resolution electromagnetic tomography (eLORETA). Depression symptom was assessed using the Beck Depression Inventory (BDI-II) and cognitive function was assessed by Verbal Fluency Test (VFT), Rey Auditory Verbal Learning Test (RAVLT), Stroop Test, and Wisconsin Card Sorting Test (WCST). Results: Responders to rTMS showed significantly lower DMN activity at baseline and a significant decrease in SMN connectivity after treatment. Non-responders did not significantly differ from the control group at the baseline and they showed higher activity in the SMN, visual network, and visual perception network compared to control group following treatment. Bilateral rTMS resulted in significant changes in the executive functions, verbal memory, and depression symptoms. No significant changes were observed in selective attention and verbal fluency. Conclusion: Bilateral stimulation of DLPFC, as the main node of CEN, results in changes in the activity of the SMN and consequently improves verbal memory and executive functions in patients with bipolar depression.
KEYWORDS: bilateral transcranial magnetic stimulation; bipolar depression; cognitive functions; default mode network; low-resolution electromagnetic tomography; resting state networks; sensorimotor network
PMID: 30233346 PMCID: PMC6135217 DOI: 10.3389/fnhum.2018.00356