A purposely designed neural signal amplifier for short interval stimulation and recording microneurography using a common electrode

‘Common Electrode’ microneurography (i.e. stimulating a nerve and recording return afferent neural activity through the same microelectrode facilitates investigation of linkages between sensory and motor nervous systems in humans. Currently there is no commercial product designed specifically to conduct common electrode microneurography experiments. However, such experiments would advance investigations in several key areas including spinal injury research.In this paper, we report on the successful production and testing (on a human subject) of an integrated amplifier built specifically for this purpose. The amplifier was built using commercially available components to allow for both easy and economical manufacture. In particular, we report on the design requirements and outline our chosen design solutions.The amplifier handles low-level neural signals amidst large 50 Hz interference, with protection against potentially high stimulation voltages of over 100 V dc, with minimal cross-coupling of rapid stimulus pulses onto the high gain amplifier's input, and a short ‘blocking’ time between stimulation and recording. The amplifier also includes necessary filters, selectable gains and internal stimulator triggering circuits to provide a simple, integrated solution for common electrode operation on human subjects.