  Objective: A model is presented to evaluate the viability of using electrical
impedance tomography (EIT) with a nerve cuff to record neural activity in
peripheral nerves. Approach: Established modelling approaches in neural-EIT are
expanded on to be used, for the first time, on myelinated fibres which are
abundant in mammalian peripheral nerves and transmit motor commands. Main
results: Fibre impedance models indicate activity in unmyelinated fibres can be
screened out using operating frequencies above 100 Hz. At 1 kHz and 10 mm
electrode spacing, impedance magnitude of inactive intra-fascicle tissue and
the fraction changes during neural activity are estimated to be 1,142
{\Omega}.cm and -8.8x10-4, respectively, with a transverse current, and 328
{\Omega}.cm & -0.30, respectively with a longitudinal current. We show that a
novel EIT drive and measurement electrode pattern which utilises longitudinal
current and longitudinal differential boundary voltage measurements could
distinguish activity in different fascicles of a three-fascicle mammalian nerve
using pseudo-experimental data synthesised to replicate real operating
conditions. Significance: The results of this study provide an estimate of the
transient change in impedance of intra-fascicle tissue during neural activity
in mammalian nerve, and present a viable EIT electrode pattern, both of which
are critical steps towards implementing EIT in a nerve cuff for neural
prosthetics interfaces.
