Abbas, J. J. | Search bioRxiv

bioRxiv2026

Selective Activation of Nerve Fiber Subpopulations with Intrafascicular Stimulation

BackgroundPeripheral nerve stimulation (PNS) is most effective when specific nerve fiber subpopulations are activated, while minimizing off-target activation, which may cause undesirable side effects. This selectivity depends primarily on electrode design and charge delivery. We hypothesized that selective PNS could be achieved through electrode placement and intrafascicular electric field steering using Longitudinal Intrafascicular Electrodes (LIFEs). MethodsLIFEs were implanted into the tibial fascicle of the sciatic nerve of 17 anesthetized adult rats. We tested whether electrodes positioned at different cross-sectional and longitudinal locations within the same fascicle, together with different electric field-steering approaches produced distinct activation patterns in the gastrocnemius lateralis muscle. Muscle responses were measured using high-density epimysial electromyography (HD-eEMG). ResultsElectrodes placed at different locations within the same fascicle activated distinct muscle regions, demonstrating intrafascicular selectivity. Bipolar stimulation recruited nerve fibers differently than monopolar stimulation, showing that electric field steering can further shape the selective recruitment. In both configurations, increasing the stimulation amplitude produced a graded increase in muscle activation. Furthermore, our findings demonstrated that HD-eEMG is an effective tool for evaluating intrafascicular selectivity. ConclusionThese findings suggest that improving on-target selectivity may support next-generation bioelectronic therapies with better outcomes and fewer side effects, potentially enabling more precise, organ-specific neuromodulation. Using multiple intrafascicular electrodes may provide two complementary strategies for enhancing selectivity: strategic intrafascicular placement to access different fiber subpopulations and bipolar configurations to steer recruitment beyond what a single electrode can achieve.

bioengineering↗

bioRxiv2018

Restoring ventilatory control using an adaptive bioelectronic system

Key Points SummaryO_LIElectrical stimulation of the diaphragm muscle or phrenic nerve, or ventilatory pacing, serves as an alternative to mechanical ventilation.\nC_LIO_LICurrently available ventilatory pacing systems are open-loop, requiring long set-up sessions and frequent tuning.\nC_LIO_LIA neuromorphic closed-loop bioelectronic controller capable of autonomously adapting current amplitude to achieve a desired breath volume profile has been developed.\nC_LIO_LIThe controller was able to achieve a desired volume profile in intact animals and restore tidal volume to values observed prior to injury in spinal cord hemisected animals.\nC_LIO_LIThis controller architecture allows for ventilatory pacing that requires minimal technician input during setup and constantly adapts to account for changes such as those induced by muscle fatigue.\nC_LIO_LIThe adaptive control system could be used as a respiratory rehabilitation tool to strengthen inspiratory muscles and for automated weaning from mechanical ventilation.\nC_LI\n\nAbstractVentilatory pacing via electrical stimulation of the phrenic nerve or of the diaphragm has been shown to enhance quality of life compared to mechanical ventilation. However, commercially-available ventilatory pacing devices require initial manual specification of stimulation parameters and frequent adjustment to achieve and maintain suitable ventilation over long periods of time. Here, we have developed an adaptive, closed-loop, neuromorphic, pattern-shaping controller capable of automatically determining a suitable stimulation pattern and adapting it to maintain a desired breath volume profile on a breath-by-breath basis. In vivo studies in anesthetized intact and C2-hemisected male Sprague-Dawley rats indicated that the controller was capable of automatically adapting stimulation parameters to attain a desired volume profile. Despite diaphragm hemiparesis, the controller was able to achieve a desired volume in the injured animals that did not differ from the tidal volume observed prior to injury (p=0.39). The closed-loop controller was developed and parametrized in a computational testbed prior to in-vivo assessment. This bioelectronic technology could serve as an individualized and autonomous respiratory pacing approach for support or recovery from ventilatory deficiency.

physiology↗