Frequency-Dependent Changes of Spontaneous Low-Frequency Fluctuations in Patients with Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness among older adults. AMD affects the patient's ability to read, write and recognize faces. Prior neuroimaging studies revealed abnormal functional connectivity within visual network and default mode network (DMN). 25 diagnosed AMD patients and 25 age, sex matched healthy controls were recruited into our study for resting-state functional magnetic resonance imaging (rs-fMRI) scans. Three different low frequency fluctuations metrics including amplitude of low-frequency fluctuation (ALFF), fractional ALFF (fALFF), and percent amplitude of fluctuation (PerAF) were introduced to detect and analyze spontaneous brain activity between AMD and HCs. For each metrics, traditional frequency band (0.01–0.08 Hz), slow-4 frequency band (0.027–0.073 Hz) and slow-5 frequency band (0.01–0.027 Hz) were examined respectively. Compared to HCs group, our result revealed that significant difference in ALFF, fALFF and PerAF showed in several brain regions including orbital frontal gyrus, fusiform gyrus, amygdala, precuneus, angular gyrus, median cingulate gyrus and rectus gyrus in AMD group at traditional frequency band. Moreover, findings of the present study demonstrated that abnormal spontaneous brain activity of fALFF in AMD is frequency-dependent, and may provide a new perspective to explain the pathological mechanism of AMD.