Neural Oscillation Abnormalities and Abnormal Dynamic Network Connectivity in δ Frequency Band in Patients with Mild Cognitive Impairment Based on Resting-State Electroencephalogram

<bold>Objective</bold>Based on resting-state electroencephalogram (EEG) data, analyze the abnormalities in neural oscillations within brain regions as well as the abnormal connectivity patterns of dynamic brain networks in the delta frequency band among patients with mild cognitive impairment (MCI). <bold>Methods</bold> From November 2022 to May 2023, 41 elderly individuals were selected from Min'an Community, Qingyang District, Chengdu City, as the study subjects. Among them, 21 were in the MCI group, and 20 were in the healthy control group (control group). A 5-minute resting-state EEG data was collected from each participant using an EEG acquisition system. Analyze the power spectral density (PSD) of each electrode within the delta frequency band; Employ the directed transfer function (DTF) to construct resting-state dynamic causal brain networks, and concurrently analyze brain connectivity with statistically significant differences as well as their correlations with the Montreal Cognitive Assessment (MoCA) scores.<bold>Results</bold>(1) PSD: In the delta frequency band, the control group exhibited stronger delta oscillations at one electrode in the prefrontal lobe (F7), one electrode in the parietal lobe (CP6), and two electrodes in the occipital lobe (PO3, PO7) (P &lt; 0.05). The MCI group showed stronger delta oscillations at seven electrodes in the prefrontal lobe (F8, FP2, AF3, Fz, FC1, FC2, FC5), eight electrodes in the parietal lobe (CP1, CP2, CP5, P3, P4, P7, P8, Pz), one electrode in the temporal lobe (T7), and two electrodes in the central region (C4, CZ) (P &lt; 0.05).(2)Resting-state time-invariant dynamic networks: In the delta frequency band, the control group demonstrated significantly enhanced brain connectivity flowing from the prefrontal lobe (AF3) to the prefrontal lobe (AF4) (P &lt; 0.05). The MCI group exhibited significantly enhanced top-down brain connectivity from the prefrontal lobe (FZ, F8) to the parietal lobe (P3), bottom-up brain connectivity from the parietal lobe (CP5) to the prefrontal lobe (FP2, F3), brain connectivity from the parietal lobe (P3) to the central region (C3) (P &lt; 0.05), as well as bottom-up brain connectivity from the occipital lobe (PO3) to the prefrontal lobe (F7), the central region (C4), and the parietal lobe (CP5) (P &lt; 0.05). In the resting state, the enhanced brain connections significantly correlated with the MOCA score include interactive brain connections between the prefrontal and parietal lobes (r = -0.37, P = 0.012; r = -0.41, P = 0.007), as well as bottom-up long-range connections from the occipital lobe to the central region and the parietal lobe (r = -0.34, P = 0.030; r = -0.37, P = 0.010).<bold>Conclusion</bold>MCI exhibited enhanced delta oscillations across multiple electrodes in various brain regions, predominantly distributed in the frontal and parietal lobes. In the delta frequency band, resting-state brain network connectivity showed significant abnormalities, primarily characterized by markedly enhanced mutual connectivity between the prefrontal and parietal lobes, as well as bottom-up brain connections from the occipital lobe to the central region and the parietal lobe.