There have been theoretical studies presented that postulate a change in the stimulus current amplitude required to recruit nerve fibers with different stimulus current pulse widths. Based on these theoretical predictions, it has been suggested that the stimulus pulse width parameter may be used to selectively recruit fibers of different sizes and that this selectivity should increase with increasing distance from the stimulus electrode. In this paper, a simulation study of the recruitment patterns of a population of motor nerve fibers with a histologically accurate fiber diameter distribution is presented. Nerve fiber excitation simulations coupled with a time varying field simulation suggest that, for surface stimulation, there is only a marginal selectivity achievable in the average nerve fiber diameter that is recruited across the range of commonly used stimulus pulse widths but this selectivity also increases with increased electrode distance. Experimental evidence consisting of estimates of nerve fiber diameter based on motor unit latency studies is also presented that is consistent with the predictions made by the electromagnetic field and nerve fiber excitation simulations.

Abstract-There have been various theoretical and experi mental studies presented in the literature that focus on interfacing neurons with discrete electronic devices, such as transistors. From both a theoretical and experimental perspective, these studies have emphasized the variability in the characteristics of the detected action potential from the nerve cell. The demonstrated lack of reproducible fidelity of the nerve cell action potential at the device junction would make it impractical to implement these devices in any neural prosthetic application where reliable detection of the action potential was a prerequisite. In this study, the effects of several different physical parameters on the fidelity of the de tected action potential at the device junction are investigated and discussed. The impact of variations in the extracellular resistivity, which directly affects the junction seal resistance, is studied along with the impact of variable nerve cell membrane capacitance and variations in the injected charge. These parameters are discussed in the context of their suitability to design manipulation for the purpose of improving the fidelity of the detected neural action potential. In addition to investigating the effects of variations in these parameters, the applicability of the linear equivalent circuit approach to calculating the junction potential is investigated.Index Terms-Nervous system, neural systems, neural elec tronics, neuron transistor interfacing, neuron transistor.

Abstract-The ability to determine the characteristics of peripheral nerve fiber size distributions would provide additional information to clinicians for the diagnosis of specific pathologies of the peripheral nervous system. Investigation of these conditions, using electro-diagnostic techniques, is advantageous in the sense that such techniques tend to be minimally invasive yet provide valuable diagnostic information. One of the principal electro-diagnostic tools available to the clinician is the nerve conduction velocity test. While the peripheral nerve conduction velocity test can provide useful information to the clinician regarding the viability of the nerve under study, it is a single parameter test that yields no detailed information about the characteristics of the functioning nerve fibers within the nerve trunk. In this study we present a technique based on a decomposition of the maximal compound evoked potential and subsequent determination of the group delay of the contributing nerve fibers. The fiber group delay is then utilized as an initial estimation of the nerve fiber size distribution and the concomitant temporal propagation delays of the associated single fiber evoked potentials to a reference electrode. Subsequently the estimated single fiber evoked potentials are optimized against the template maximal compound evoked potential using a simulated annealing algorithm. Simulation studies, based on deterministic single fiber action potential functions, are used to demonstrate the robustness of the proposed technique in the presence of noise associated with variations in distance between the nerve fibers and the recording electrodes between the two recording sites.

Abstract-The ability to determine the characteristics of peripheral nerve fiber size distributions would provide additional information to clini cians for the diagnosis of specific pathologies of the peripheral nervous sys tem. Investigation of these conditions, using electrodiagnostic techniques, is advantageous in the sense that such techniques tend to be minimally invasive yet provide valuable diagnostic information. One of the principal electrodiagnostic tools available to the clinician is the nerve conduction ve locity test. While the peripheral nerve conduction velocity test can provide useful information to the clinician regarding the viability of the nerve under study, it is a single-parameter test that yields no detailed information about the characteristics of the functioning nerve fibers within the nerve trunk. In this study, we present a technique based on decomposition of the maximal compound evoked potential and subsequent determination of the group delay of the contributing nerve fibers. The fiber group delay is then utilized as an initial estimation of the nerve fiber size distribution and the associ ated temporal propagation delays of the single-fiber-evoked potentials to a reference electrode. Simulation studies, based on deterministic single-fiber action potential functions, are used to demonstrate the robustness of the proposed technique in the presence of simulated noise associated with the recording process.Index Terms-Conduction velocity distribution (CVD), group delay, nerve fiber size distribution.

Abstract-There have been numerous studies presented in the literature related to the simulation of the interaction between biological neurons and electronic devices. A complicating factor associated with these simulations is the algebraic complexity involved in implementation. This complication has impeded simulation of more involved neural-electronic circuitry and con sequently has limited potential advancements in the integration of biological neurons with synthetic electronics. In this paper, we describe a modification to a previously proposed SPICE based Hodgkin-Huxley neuron model that demonstrates more physio logically relevant electrical behavior. We utilize this SPICE based neuron model in conjunction with an external circuit that allows for artificial selective inhibition of neural spiking. The neural firing control scheme proposed herein would allow for action potential frequency modulation of neural activity that, if devel oped further, could potentially be applied to suppress undesirable neural activity that manifests symptomatically as the tremors or seizures associated with specific pathologies of the nervous system.