Differences in Functional Connectivity between Normal Controls and Mild Cognitive Impairment in Motion Detection Tasks

Abstract

AbstractBackgroundIt has long been observed that the abnormal brain functions in Alzheimer’s disease (AD) and mild cognitive impairment (MCI) are closely related to the weakening or loss of functional connectivity across certain brain regions. At the same time, the decreased cross‐connectivity is often accompanied by increased connectivity between some other regions, and this was considered to reflect the compensatory mechanisms of the brain. In this research, we investigate the differences in time‐varying functional connectivity between normal controls (NC) and MCI patients in motion detection tasks.MethodOur research is based on task‐based EEG (64‐channel), where the participants were asked to perform a motion direction discrimination task. The current dataset includes 60 consensus‐diagnosed, community‐dwelling African Americans (ages 60‐90 years, 30 NC and 30 MCI) recruited through the Wayne State Institute of Gerontology Healthy Black Elders Center and the Michigan Alzheimer’s Disease Research Center with subjective cognitive complaints.We evaluated the time‐varying functional connectivity at different time periods of the motion‐detection task across all the possible EEG region pairs, in terms of the Pearson correlation vector of the current source density. For each task trial, the successive time periods being examined included: stimulus onset to Go/NoGo indication, Go/NoGo indication to motion‐stop, and the button‐press period. For each subject, we calculated the mean, maximum and minimum of the Pearson correlation vector for each EEG region pair and each time period as features, and then selected the features where NC and MCI show a significant difference (p‐value<0.05 in the t‐test).ResultOur analysis indicated that NC shows significantly higher connectivity across EEG region pairs Right Frontal‐Left Central (through most periods), Left Temporal‐Medial Central and Left Temporal‐Occipital (in button‐press period). On the other hand, MCI shows signigicantly high connectivity across Medial Parietal‐Occipital (through all the periods), which may reflect the compensatory mechanisms of the brain.ConclusionHC and MCI do show significant difference in functional connectivity during the motion detection task, and the EEG regions pairs Medial Parietal‐Occipital, and Right Frontal‐Left Central shown to be excellent choices for biomarker development for the discrimination of NC and MCI.Funding: NSF‐2032709/Li; NIH‐ P30AG05376004/Paulson; NIH‐1R21AG046637‐01A1/Kavcic and NIH‐1R01AG054484‐01A1/Kavcic;