Benchmark I ixk51
Specific Aims
Since peripheral nerves carry many different signals from the brain to limbs and organs, closed-loop devices such as advanced prosthetics and functional electrical stimulation (FES) systems can use neural signal as feedback for control. Selective recording, or the ability to record from a specific fascicle without picking up signal from other fascicles, is therefore vital for this purpose. There is literature available about selective extra-neural cuff electrodes as well as intra-fascicular microelectrode arrays, but no published record exists of using interfascicular electrodes for the purpose of recording. The need is evident for an electrode that does not invade the fascicle (in order to prevent neuronal damage) and is still able to selectively record neural signals to be useful as feedback in FES and prosthetic systems. Our hypothesis is that interfascicular electrodes are selective and safe for the purpose of neural recording. Testing the hypothesis will be accomplished by addressing the specific aims outlined below. First, a mathematical model will be constructed to determine the theoretical effectiveness of inter-fascicular electrodes (Aim 1). Second, selectivity results from acute experiments will be compared to the mathematically-obtained selectivity measures to validate the model and prove the short-term safety and efficacy of the electrodes (Aim 2). Finally, a set of chronic experiments will be performed to evaluate long-term performance of the electrode and ultimately pave the way for human trials (Aim 3). These experiments will serve as a comprehensive quantification of inter-fascicular space for the purpose of neural recording.
Aim 1: To validate the claim that inter-fascicular electrodes can selectively record signals from separate fascicles using a finite element model a. Determine the relationship between the number of inter-fascicular contacts and the selectivity of the electrodes. b. Find the maximum distance that a contact can be away from a target fascicle and still selectively record from it. c. Evaluate the effect of adding more fascicles and inhomogeneities (blood vessels, connective tissue) on the selectivity of the electrodes.
Aim 2: To quantify the recording selectivity of interfascicular electrodes in animal models a. Find the minimum number of inter-fascicular contacts required for the selectivity to approach a maximum. b. Record spontaneous neural activity to evaluate the signal-to-noise ratio of inter-fascicular electrodes. c. Review the histology of nerves to rule out acute neuronal damage, as quantified by demyelination and neuronal necrosis.
Aim 3: To determine the viability of using interfascicular electrodes in chronic animal studies a. Evaluate the selectivity of the inter-fascicular electrode as a function of time within a 10-week observation period. b. Determine the signal-to-noise ratio of the electrodes within a 10-week observation period to see if there is any deterioration in signal quality. c. Evaluate the histology of the nerves at the end of the observation period to rule out chronic nerve damage, using a nerve cuff electrode as a control.
