Closed-Loop Multimodal Neuromodulation of Vagus Nerve for Control of Heart Rate

Area of Science:

• Biomedical Engineering
• Neuroscience
• Control Systems

Background:

• Autonomic regulation necessitates bidirectional nervous system control (up-regulation and down-regulation).
• Existing electrical neuromodulation systems require real-time adaptation to physiological changes.
• Vagus nerve stimulation (VNS) frequency modulates neural activity, while kilohertz frequency alternating current (KHFAC) blocks nerve conduction.

Purpose of the Study:

• To develop and evaluate a closed-loop neuromodulation system for precise autonomic regulation.
• To investigate the efficacy of fuzzy logic control (FLC) in managing complex physiological responses.
• To control heart rate using a combination of VNS and KHFAC delivered via a bipolar electrode on the vagus nerve.

Main Methods:

• A single bipolar electrode was surgically placed on the vagus nerve.
• A fuzzy logic controller (FLC) was implemented to manage stimulation parameters.
• The system delivered both VNS (1-30 Hz) for neural activation and KHFAC for neural inhibition to control heart rate.

Main Results:

• The FLC successfully adjusted heart rate to target values.
• The system maintained a constant heart rate despite physiological perturbations.
• Fuzzy logic control demonstrated robustness in handling system delays and discontinuities.

Conclusions:

• A closed-loop system utilizing FLC, VNS, and KHFAC can effectively regulate heart rate.
• This approach offers a promising method for bidirectional autonomic nervous system modulation.
• The FLC's ability to manage complex system dynamics is crucial for real-time autonomic control.