Functional connectivity between parietal cortex and the cardiac autonomic system in uremics

Abstract

Although the central autonomic network (CAN) has been well researched in animal models, the CAN in humans is still unclear, especially for cardiovascular control. This study aimed to investigate which areas of the cerebral cortices are associated with the peripheral cardiac autonomic control involved in the CAN in uremic patients with autonomic dysfunction and normal controls. The central and peripheral autonomic network in 19 uremic patients with significant autonomic dysfunction and 24 age- and sex-matched controls [mean age ± standard deviation (SD), 55.16 ± 10.45 years and 55.42 ± 5.42 years, respectively] were evaluated by simultaneous spectral analysis of electroencephalography (EEG) and electrocardiography recording (ECG), along with serial autonomic tests [autonomic questionnaire and orthostatic blood pressure (BP) change]. Only frequency-domain heart rate variability (f-HRV) during the deep-breathing stage could differentiate the two groups. Although there is no significant difference in f-HRV during the quiet-breathing stage, different patterns of central oscillation and their correlation with peripheral cardiac autonomic indices could be found for the two groups. Although the power of specific EEG bands under electrode T3 and T6 correlated significantly with the power of peripheral HRV indices in the control group, those under electrodes P3 and Pz had significant correlations in the uremic group suggesting a role of functional connectivity between them. In addition, sympathetic activity is correlated with slow wave EEG (theta/delta) power whereas parasympathetic activity is correlated with fast wave EEG (beta) power. In conclusion, there is functional connectivity between the parietal cortex and the peripheral cardiac autonomic system (PAN) in uremics and the pattern of central autonomic connectivity differs between uremic patients with autonomic dysfunction and normal controls.

Keywords: Central autonomic network; Electroencephalography; Heart rate variability; Spectral analysis; Uremia.

Figure 1

During the quiet‐breathing stage, (A) there were significant correlations between HRV indices and specific EEG band power at the T3 and T6 electrodes in the control group; (B) significant correlations between HRV indices and specific EEG band power at the Pz and P3 electrodes in the uremic group. During the deep‐breathing stage, (C) there were significant correlations between HRV indices and specific EEG band power at the T4 electrodes in the control group; (D) significant correlations between HRV indices and specific EEG band power at the C3, C4, Fz, F7, and F8 electrodes in the uremic group. EEG = electroencephalography; HRV = heart rate variability.