Figure 3
Abnormal E–I balance in AD patients, but not in MCI or SCD patients. (A,E) Lower DFA exponents in the extended alpha band (6–13 Hz) in parieto-occipital cortex and hippocampi suggest E–I imbalance in AD patients and HY compared to HE. (B,F) fE/I values of ~ 1.0 indicate E–I balance, but many HE and HY subjects showed fE/I < 1.0, which suggest inhibition-dominated activity. Median fE/I was relatively higher in AD patients compared to HE, suggesting less inhibition, but more balanced networks. (C,G) The number of ROIs for which no fE/I value was calculated (because DFA < 0.55) was higher in AD and HY than HE. (D,H) The aperiodic exponent of the gamma frequency power spectra was lower in AD, suggesting relatively more excitation in the parieto-occipital cortex compared to HE. Each symbol shows the average of all ROIs within the parieto-occipital cortex or the hippocampi of a single subject. Bar graphs show the median and interquartile range per group. Outcome measures for each group (HY, SCD, MCI, AD) were compared to HE using the Kruskal–Wallis test. DFA detrended fluctuation analyses, fE/I functional excitation inhibition, ROIs region of interest, HY healthy young controls, HE healthy elderly controls, SCD subjective cognitive decline, MCI mild cognitive impairment, AD dementia due to Alzheimer’s disease; *p < 0.05; **p < 0.01, ***p < 0.001.
