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

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.