Frequency-Dependent Brain Regional Homogeneity Alterations in Patients with Mild Cognitive Impairment during Working Memory State Relative to Resting State

Abstract

Several studies have reported working memory deficits in patients with mild cognitive impairment (MCI). However, previous studies investigating the neural mechanisms of MCI have primarily focused on brain activity alterations during working memory tasks. No study to date has compared brain network alterations in the working memory state between MCI patients and normal control (NC) subjects. Therefore, using the index of regional homogeneity (ReHo), we explored brain network impairments in MCI patients during a working memory task relative to the resting state, and identified frequency-dependent effects in separate frequency bands.Our results indicate that, in MCI patients, ReHo is altered in the posterior cingulate cortex (PCC) in the slow-3 band (0.073–0.198 Hz), and in the bottom of the right occipital lobe and part of the right cerebellum, the right thalamus, a diffusing region in the bilateral prefrontal cortex (PFC), the left and right parietal-occipital regions, and the right angular gyrus in the slow-5 band (0.01–0.027 Hz). Furthermore, in NCs, the value of ReHo in clusters belonging to the default mode network (DMN) decreased, while the value of ReHo in clusters belonging to the attentional network increased during the task state. However, this pattern was reversed in MCI patients, and was associated with decreased working memory performance. In addition, we identified altered functional connectivity of the abovementioned regions with other parts of the brain in MCI patients. This is the first study to compare frequency-dependent alterations of ReHo in MCI patients between resting and working memory states. The results provide a new perspective regarding the neural mechanisms of working memory deficits in MCI patients, and extend our knowledge of altered brain patterns in resting and task-evoked states.

Regional Dynamics of the Resting Brain in Amyotrophic Lateral Sclerosis Using Fractional Amplitude of Low-Frequency Fluctuations and Regional Homogeneity Analyses

“…Further studies considering a larger sample or providing enough statistical power will be necessary to better investigate the prevalence of our findings. However, such a small sample is often found in the neurodegeneration literature, including studies evaluating the fMRI measures here studied (Luo et al, 2012;Wang et al, 2015;Wang et al, 2016). Another important limitation is the lack of clinical measures (e.g.…”

Task‐related changes in degree centrality and local coherence of the posterior cingulate cortex after major cardiac surgery in older adults

“…Additionally, dPCC connectivity appears to be greater with attentional networks at rest, suggesting that this PCC subregion may be critical to internal/external switching of attentional focus between the DMN and FPN (Leech, Kamourieh, Beckmann, & Sharp, ; Leech et al, ). Alteration in DMN‐associated PCC functional connectivity during working memory task performance has been described in various patient populations, including older adults with mild cognitive impairment (Kochan et al, ; Wang, Li, Yu, Huang, & Li, ), traumatic brain injury (van der Horn et al, ), cerebrovascular disease (Papma et al, ), and psychiatric conditions (Bedard et al, ; Oflaz et al, ). Additionally, individuals without objective cognitive test deficits who nonetheless complained of cognitive problems, exhibited greater functional activity within the DMN‐associated PCC and FPN‐associated precuneus regions during increased working memory demands (Dumas et al, ).…”

Aberrant Brain Regional Homogeneity and Functional Connectivity in Middle-Aged T2DM Patients: A Resting-State Functional MRI Study

“…As effective indicators reflecting the intrinsic organization of the resting brain, ReHo and FC have been conjunctively applied in a number of studies of complex brain functional activity and its alterations in diseases and aging (Damoiseaux et al, 2008 ; Jiang et al, 2015 ; Cui et al, 2016 ; Wang et al, 2016 ). These two indices have proved to be mutually complementary for detecting local and remote brain activity synchronization.…”