Intraneural stimulation using wire-microelectrode arrays: analysis of force steps in recruitment curves

In acute experiments on six Wistar rats, a wire-microelectrode array was inserted into the common peroneal nerve. A 5-channel array and a 24-channel array were available. Each electrode in the array was used to generate a twitch contraction force recruitment curve for the extensor digitorum longus muscle. We constructed a histogram of the pooled force steps in all recruitment curves. From a comparison of this experimental histogram with one estimated from literature data, we found that the force steps encountered in our experiments are in the same range as those from the literature-based estimated distribution. Discrepancies between the experimental and the literature-based histogram might be ascribed to an approximation used in the estimated distribution. We conclude that force step histograms appear to provide a simple means for estimating motor unit twitch force distributions, and thus are of value in studies of intraneural selective stimulatio

Endoneural selective stimulating using wire-microelectrode arrays

In acute experiments eight 5- to 24-wire-microelectrode arrays were inserted into the common peroneal nerve of the rat, to investigate whether the electrodes could selectively stimulate motor units of the extensor digitorum longus (EDL) muscle. Twitch-force-recruitment curves were measured from the EDL for each array electrode. The curves were plotted on a double-logarithmic scale and parameterized by the low-force slope (which represents the power p in the power-law relationship of force F versus stimulus current I, or F~Ip) and the threshold current. The slopes and threshold currents measured with array electrodes did not differ significantly from those obtained with randomly inserted single wire-microelectrodes. This indicates that, although involving a more invasive insertion procedure, electrode arrays provide neural contacts with low-force recruitment properties similar to those of single wires. Array results revealed partial blocking of neural conduction, similar to that reported with microneurographic insertion with single needles. The efficiency of the array was defined as the fraction of array electrodes selectively contacting a motor unit and evoking the corresponding threshold force. Efficiency thus expresses the practical value of the used electrode array in terms of the total number of distinct threshold forces that can be stimulated by selecting the appropriate electrodes. The eight arrays were capable of evoking threshold forces selectively with an average efficiency of 0.81 (or 81%

A gate-array/multi-electrode device: circuit performance and interfacing

The Twente 128-fold 3-dimensional multi-micro electrode device for endoneural stimulation is controlled by a 4×4 mm CMOS gate array chip. The chip contains the electronic circuitry, i.e. eight 16-channel multiplexers, eight double current sources and six differential amplifiers. Control of the gate array circuitry by a PC is done by a PCI interface. We present (aspects of) the design and realization of the PCI interface, as well as the simulated and measured performance figures of the current sources and amplifier

3D Neuro-electronic interface devices for neuromuscular control: Design studies and realisation steps

In order to design the shape and dimensions of new 3D multi-microelectrode information transducers properly, i. e. adapted to the scale of information delivery to and from peripheral nerve fibres, a number of studies were, and still are, being performed on modelling and simulation of electrical volume conduction inside and outside nerves, on animal experiments on stimulation and recording with single wires and linear arrays, and on new technologies for 3D micro-fabrication. This paper presents a selection of the results of these `Neurotechnology¿ studies at the University of Twente. The experimental and simulation results apply primarily to the peripheral motor nerves of the rat, but are also of interest for neural interfacing with myelinated nerves in man, as fascicles in man are about the same size as in the rat

The effect of spatial clustering of motor fibers in a nerve fascicle on force recruitment during electrical stimulation

Force recruitment curves have been determined using stimulation with an intraneural wire electrode. The recruitment curves vary with the position of the electrode in the fiber bundle. The results recruitment curves depends on the position of the electrode seem to support previous findings which indicated that the low density of nodes of Rauvier and a possible clusteriug of motor fibers within the fiber bundle might have a major impact on the efficacy of intraneural electrical stimulation