Fascicle specific targeting for selective peripheral nerve stimulation

Abstract

Objective. Electrical stimulation is a blunt tool for evoking neural activity. Neurons are naturally activated asynchronously and non-uniformly, whereas stimulation drives simultaneous activity within a population of cells. These differences in activation pattern can result in unintended side effects, including muddled sensory percepts and undesirable muscle contractions. These effects can be mitigated by the placement of electrodes in close approximation to nerve fibers and careful selection of the neural interface's location. This work describes the benefits of placing electrodes within specific fascicles of peripheral nerve to form selective neural interfaces for bidirectional neuroprosthetic devices. Approach. Chronic electrodes were targeted to individual fascicles of the ulnar and median nerves in the forearm of four human subjects. During the surgical implant procedure, fascicles were dissected from each nerve, and functional testing was used to identify the relative composition of sensory and motor fibers within each. FAST-LIFE arrays, composed of longitudinal intrafascicular arrays and fascicular cuff electrodes, were implanted in each fascicle. The location, quality, and stimulation parameters associated with sensations evoked by electrical stimulation on these electrodes were characterized throughout the 90–180 d implant period. Main results. FAST-LIFE arrays enable selective and chronic electrical stimulation of individual peripheral nerve fascicles. The quality of sensations evoked by stimulation in each fascicle is predictable and distinct; subjects reported tactile and cutaneous sensations during stimulation of sensory fascicles and deeper proprioceptive sensations during stimulation of motor fascicles. Stimulation thresholds and strength-duration time constants were typically higher within sensory fascicles. Significance. Highly selective, stable neural interfaces can be created by placing electrodes within and around single fascicles of peripheral nerves. This method enables targeting electrodes to nerve fibers that innervate a specific body region or have specific functions. Fascicle-specific interfacing techniques have broad potential to maximize the therapeutic effects of electrical stimulation in many neuromodulation applications. (Clinical Trial ID NCT02994160.)

Long-Term Performance of Utah Slanted Electrode Arrays and Intramuscular Electromyographic Leads Implanted Chronically in Human Arm Nerves and Muscles

“…10). These sizes are consistent with percepts evoked via longitudinal intrafascicular arrays [26]. There were no signfiicance differences in the size of USEA-evoked percepts over time (p = 0.65 for S5-M, p = 0.07 for S5-U, p = 0.44 for S6-M, p = 0.82 for S6-U; individual one-way Kruskal-Wallis).…”

A bioelectric neural interface towards intuitive prosthetic control for amputees

“…The "sensory" fascicles are found by placing needle electrodes in the scalp over the primary sensory cortex and observing somatosensory evoked potentials (SSEP) elicited by the nerve stimulation. Nevertheless, it is worth noting that there is no clear separation between motor and sensory functions as shown in [40]. An electrode with strong motor control signals can frequently be found on the "sensory" fascicles and vice versa.…”

“…A combination of a higher system resolution as well as system miniaturization and low power implementation allows Scorpius to isolate weak neural signals from large amplitude artifacts and interferences, which in turn enable the high DOF motor decoding through deep neural networks. 3 shows the construction of the microelectrode array that is an extended version of the design reported in [4,40]. Each array consists of four cuff contacts and an intrafascicular shank with ten longitudinal intrafascicular electrodes (LIFE) contacts spaced 0.5mm apart.…”

“…Furthermore, we are also working on incorporating electrical stimulation capabilities into the proposed platform. The feasibility of using the same electrode array for stimulation has been explored in [40]. This will allow the system to provide neural feedback to the patient including tactile and proprioceptive responses, which are essential for a realistic neuroprosthesis [13,14].…”

“…As a result, a substantial level of processing and pattern recognition is required to isolate and extract the desired data features. More recent studies on microelectrodes [4,40], bioelectronics [67], AI algorithms [9], and clinical validations [7,12,39,55,69] argue multi-DOF motor control via the peripheral neural pathways may be a more effective and promising approach. Fig.…”