Recording and quantifying sympathetic outflow to muscle and skin in humans: methods, caveats and challenges

Abstract

The development of microneurography, in which the electrical activity of axons can be recorded via an intrafascicular microelectrode inserted through the skin into a peripheral nerve in awake human participants, has contributed a great deal to our understanding of sensorimotor control and the control of sympathetic outflow to muscle and skin. This review summarises the different approaches to recording muscle sympathetic nerve activity (MSNA) and skin sympathetic nerve activity (SSNA), together with discussion on the issues that determine the quality of a recording. Various analytical approaches are also described, with a primary emphasis on those developed by the author, aimed at maximizing the information content from recordings of postganglionic sympathetic nerve activity in awake humans.

Low dose ketamine reduces pain perception and blood pressure, but not muscle sympathetic nerve activity, responses during a cold pressor test

“…MSNA burst amplitude and area varied within participants and between visits given the repeated measures design (MSNA recordings from opposing arms on separate occasions due to the proximity of experimental trials) as well as within visits (due to LBNP-related shifts in the neurogram, which occurred between the repeated CPTs within each visit). Therefore, it would be inappropriate to estimate the MSNA burst amplitude or area for this particular protocol given that, even with burst amplitude and area normalization, alterations in baseline characteristics of the neurogram have a significant influence on the resultant CPT-related changes in burst amplitude and area (White et al 2015;Macefield, 2020).…”

“…Therefore, it would be inappropriate to estimate the MSNA burst amplitude or area for this particular protocol given that, even with burst amplitude and area normalization, alterations in baseline characteristics of the neurogram have a significant influence on the resultant CPT‐related changes in burst amplitude and area (White et al . 2015; Macefield, 2020).…”

Signal-averaged resting sympathetic transduction of blood pressure: is it time to account for prevailing muscle sympathetic burst frequency?

“…Microneurography was used to quantify efferent post-ganglionic multiunit MSNA (1,30). A high impedance tungsten microelectrode was inserted percutaneously and adjusted until spontaneous bursts of sympathetic activity were observed from the MSNA neurogram.…”

“…The development of the microneurographic method enabled the recording of post-ganglionic sympathetic activity directed towards skin and muscle vasculature in humans (1,2). However, one limitation of measuring sympathetic nerve activity (MSNA) remains the translation of the neural signal (e.g.…”

Absence of reliable physiological signature of illusory body ownership revealed by fine-grained autonomic measurement during the rubber hand illusion

“…Attempts to quantify sympathetic nerve traffic more directly include the established technique of microneurography[23,[39][40][41], which employs microelectrodes inserted into peripheral nerves (median or common peroneal) to measure multiunit activity (sometimes also single unit action potentials) from sympathetic axon bundles. Muscle sympathetic nerve activity shows different patterns of reactivity compared to skin sympathetic, reflecting the dependence on the baroreflex in gating sympathetic vascular control[23].…”