Differential control of sympathetic outflow to muscle and skin during physical and cognitive stressors

Transcranial magnetic stimulation (TMS) is applied both in research settings and clinically, notably in treating depression through the dorsolateral prefrontal cortex (dlPFC). We have recently shown that transcranial alternating current stimulation of the dlPFC partially entrains muscle sympathetic nerve activity (MSNA) to the stimulus. We, therefore, aimed to further explore the sympathetic properties of the dlPFC, hypothesizing that single-pulse TMS could generate de novo MSNA bursts. Microneurography was performed on the right common peroneal nerve in 12 participants. TMS pulses were then delivered to the ipsilateral dlPFC at resting motor threshold (MT) of the first dorsal interosseous muscle and at powers 20 below, 10 below, 10% above, and 20% above MT. The MT and 10% above MT intensities were also used to stimulate the right motor cortex and shoulder. Comparisons between stimulus intensities at the same site and between sites at the same intensities revealed no differences in MSNA burst frequency, burst incidence, or single MSNA spikes. Most stimulus trains, however, showed reduced burst frequency and incidence from baseline, regardless of site. This suggests that the TMS itself was evoking arousal-based sympathoinhibition, independent of dlPFC influences. It seems the dlPFC is capable of modulating MSNA but cannot directly generate bursts.

show abstract

Noninvasive Assessment of Temporal Dynamics in Sympathetic and Parasympathetic Baroreflex Responses

Suarez-Roca,

Mamoun,

Mathew

et al. 2024

Preprint

View full text Add to dashboard Cite

Background: The baroreflex system is crucial for cardiovascular regulation and autonomic homeostasis. A comprehensive assessment requires understanding the simultaneous temporal dynamics of its multiple functional branches, which traditional methods often overlook. Objective: To develop and validate a noninvasive method for simultaneously assessing the temporal dynamics of sympathetic and parasympathetic baroreflexes using pulse contour analysis and the sequence method. Methods: Beat-to-beat blood pressure and ECG recordings were analyzed from 55 preoperative cardiothoracic surgery patients in the supine position and 21 subjects from the EUROBAVAR dataset in both supine and standing positions. Systolic arterial pressure (SAP), interbeat interval (IBI), cardiac output (CO), myocardial contraction (dP/dtmax), and systemic vascular resistance (SVR) were estimated using pulse contour analysis. Baroreflex sensitivity (BRS) was calculated via the sequence method and correlated with hemodynamic and heart rate variability (HRV) parameters. Results: Parasympathetic BRS for IBI was correlated with the root mean square of successive differences of ECG RR intervals (RMSSD-HRV) at 0-beat delay. Sympathetic BRS for SVR strongly correlated with SVR, CO, and RMSSD-HRV, particularly at 3-beat delay, and was uniquely associated with SAP at 1-beat delay. Sympathetic BRS for dP/dtmax correlated with dP/dtmax at 1-beat delay. In contrast, BRS for CO correlated with CO and SVR at 0- and 3-beat delays. Postural changes mainly affected parasympathetically-mediated BRS for IBI and, to a lesser extent, the sympathetic vascular and myocardial branches. Conclusions: This method effectively captures multiple baroreflex responses and their temporal dynamics, revealing distinct autonomic mechanisms and the impact of postural changes. Further validation is warranted.

show abstract

Differential control of sympathetic outflow to muscle and skin during physical and cognitive stressors

Cited by 3 publications

References 39 publications

Photoplethysmography as a noninvasive surrogate for microneurography in measuring stress-induced sympathetic nervous activation — A machine learning approach

Photoplethysmography as a noninvasive surrogate for microneurography in measuring stress-induced sympathetic nervous activation — A machine learning approach

Single-pulse transcranial magnetic stimulation of the dorsolateral prefrontal cortex does not directly affect muscle sympathetic nerve activity in humans

Noninvasive Assessment of Temporal Dynamics in Sympathetic and Parasympathetic Baroreflex Responses

Contact Info

Product

Resources

About