Identify Changes of Brain Regional Homogeneity in Bipolar Disorder and Unipolar Depression Using Resting-State fMRI

Abstract

BackgroundTo identify changes in brain activation patterns in bipolar disorder (BD) and unipolar depression (UD) patients.Methodology/Principal FindingsResting-state fMRI scans of 16 healthy controls, 17 BD and 16 UD patients were obtained. T-test of normalized regional homogeneity (ReHo) was performed in a voxel-by-voxel manner. A combined threshold of á = 0.05, minimum cluster volume of V = 10503 mm3 (389 voxels) were used to determine ReHo differences between groups. In UD group, fMRI revealed ReHo increases in the left middle occipital lobe, right inferior parietal lobule, right precuneus and left convolution; and ReHo decreases in the left parahippocampalgyrus, right precentralgyrus, left postcentralgyrus, left precentralgyrus and left cingulated. In BD group, ReHo increases in the right insular cortex, left middle frontal gyrus, left precuneus, left occipital lobe, left parietal, left superior frontal gyrus and left thalamus; and ReHo decreases in the right anterior lobe of cerebellum, pons, right precentralgyrus, left postcentralgyrus, left inferior frontal gyrus, and right cingulate. There were some overlaps in ReHo profiles between UD and BD groups, but a marked difference was seen in the thalamus of BD.Conclusions/SignificanceThe resting-state fMRI and ReHo mapping are a promising tool to assist the detection of functional deficits and distinguish clinical and pathophysiological signs of BD and UD.

Alterations in regional homogeneity of resting-state brain activity in patients with major depressive disorder screening positive on the 32-item hypomania checklist (HCL-32)

“…Previous studies found no difference of local region activity in MTC/ITC for BD compared with HC or UD (Liang et al, 2013;Liu et al, 2012b;Liu et al, 2012c;Liu et al, 2012d). But functional connectivity between MTC and other emotion regulation related brain regions, such as prefrontal cortex, has been found increased in patients with MDD and this abnormal activity might be resulted from negative experiences or represent a dynamic prediction of expected future coactivations as a results of the overall negative expectations of depressed patients (Fox et al, 2006).…”

“…Comparing with HC, increased ReHo values in the IPC have been observed in both BD and UD, but no difference was identified when comparing with each other (Liang et al, 2013). Then the authors suggested that the ReHo abnormalities in IPC might be attributed to learning disabilities with parietal dysfunction because that depressed patients usually had low level of education compared with normal subjects (Liang et al, 2013;Shippee et al, 2011). We The postcentral cortex is conceived as primary somatosensory cortex, and receives the bulk of the thalamocortical projection from the sensory input fields.…”

“…ReHo abnormalities (either increase or decrease in ReHo value) are related to unbalanced local brain activity. In recent years, ReHo has been successfully used to investigate the brain function in healthy subjects (Kunisato et al, 2011;Luo et al, 2014) and clinical populations with psychiatric disorders Guo et al, 2011;Liang et al, 2013;Liu et al, 2012e;Zang et al, 2004). For MDD, extensively distributed abnormal brain activities have been observed during resting-state and some clinical symptoms have been related to specific abnormal patterns of brain activities (Yao et al, 2009).…”

“…However, the IPC has also been found to be involved in a wide range of different processes, ranging from action, memory, and language to mathematical problem solving and social cognition (Rolls, 1999). Comparing with HC, increased ReHo values in the IPC have been observed in both BD and UD, but no difference was identified when comparing with each other (Liang et al, 2013). Then the authors suggested that the ReHo abnormalities in IPC might be attributed to learning disabilities with parietal dysfunction because that depressed patients usually had low level of education compared with normal subjects (Liang et al, 2013;Shippee et al, 2011).…”

“…We The postcentral cortex is conceived as primary somatosensory cortex, and receives the bulk of the thalamocortical projection from the sensory input fields. BD patients (in depressive state) showed significant lower ReHo and ALFF in left postcentral cortex compared to HC (Liang et al, 2013;Liu et al, 2012a). However, more straightforward evidences are needed to interpret the implication of the abnormal brain activities in the postcentral cortex.…”