Abstract
In our previous study, measurement of muscle sympathetic nerve activity (MSNA) was conducted using a micro-needle electrode and simultaneously using a noninvasive body-surface Laplacian electrode which was mounted on a high-input-impedance buffer circuit. We observed burst-like spike potentials during Valsalva maneuver in the noninvasively measured recording after the application of a modified Wavelet-based denoising. However, the specificity of the modified method was low, resulting in the merge of MSNA bursts in microneurographic recording. We hypothesized that one cause for the low specificity is mismatching between analogue and digital signal processing for rectification and integration in the current modified method. We newly introduced an exponential time window, whose time constant is consistent with that of analogue integrator, into a digital preprocessing. The introduction of the exponential time window increased correlation coefficient between digitally and analogously processed recordings after the rectification and integration from 0.92 to 0.98 on the average for 8 segments containing MSNA bursts.
