Altered functional connectivity in patients with post-stroke memory impairment: A resting fMRI study

Abstract

Post-stroke memory dysfunction (PMD) is one of the most common forms of cognitive impairment among stroke survivors. However, only a limited number of studies have directly investigated the neural mechanisms associated with memory decline. The aim of the present study was to identify dynamic changes in the functional organization of the default mode network (DMN) and the dorsal attention network of patients with PMD. A total of 27 patients with PMD who experienced a stroke in the right hemisphere were enrolled in the current study, along with 27 healthy control subjects matched by age, sex, and educational level. A behavioral examination and functional magnetic resonance imaging scan were performed. The data were analyzed using an independent component analysis method. The results revealed a significantly increased functional connectivity between the DMN and prefrontal cortex (left middle/inferior frontal and left precentral gyri), temporal regions (left superior temporal gyrus), and bilateral and posterior cingulate gyri/precuneus (P<0.001). There was also a significantly decreased functional connectivity between the DMN and right middle temporal gyrus, left uvula, and right inferior parietal lobule, and between the dorsal attention network and prefrontal cortex (left precentral/inferior and right inferior/middle frontal gyri), right inferior parietal gyrus, and right insula (P<0.001). These results suggest that the stroke affected both the lesioned and contralesional hemispheres. The prefrontal cortex, temporal regions, insula, and posterior cingulate gyrus/precuneus serve a crucial role in memory processing.

The Local Brain Abnormalities in Patients With Transient Ischemic Attack: A Resting-State fMRI Study

“…The triangular part of right inferior frontal gyrus was involved in several cognitive processes, including attention and motor inhibition processes, as well as language performance (Hampshire et al, 2010; Tanaka et al, 2013; Hassa et al, 2016). Liu and colleagues showed decreased FC between the inferior frontal cortex and dorsal attention network in patients with post-stroke memory dysfunction (Liu et al, 2017). Moreover, the activation of the right inferior frontal gyrus may be essential for language performance in patients experiencing aphasia after left hemispheric stroke (Winhuisen et al, 2005, 2007).…”

Cortical Surface Area Rather Than Cortical Thickness Potentially Differentiates Radiation Encephalopathy at Early Stage in Patients With Nasopharyngeal Carcinoma

“…The morphologic abnormalities in the ITG observed in this study may underlie the compromised visual and verbal abilities in Post-RT. The middle and superior temporal gyrus were key nodes of the language network and have also been involved in social-affective communication ( Tomasi and Volkow, 2012 ; Cremers et al, 2015 ) and memory processing ( Liu et al, 2017 ). Actually, worse memory function, disturbance of language comprehension, and social communication disorders could be observed in Post-RT ( Lam et al, 2003 ; Hsiao et al, 2010 ; Tang et al, 2012 ).…”

Altered Neural Networks in the Papez Circuit: Implications for Cognitive Dysfunction after Cerebral Ischemia

“…They found that regional homogeneity, which measured resting-state regional brain spontaneous activity, was decreased in the PCC within the DMN and was correlated with cognitive decline [114]. Conversely, a recent study reported that functional connectivity was increased between the DMN and PCC in patients with post-stroke memory dysfunction, although in some areas within the DMN connectivity was decreased [115]. The disparity between these studies may be explained by a number of factors including the nature of the brain injury due to stroke and inclusion/exclusion criteria, such as the time frame in which patients were scanned after stroke onset.…”