A new 3D finite element model of extracellular action potentials recording with a microelectrode in a tissue slice

A new transient finite element model of extracellular action potentials recording with a microelectrode in a tissue slice is presented. The neuron model is based on the Hodgkin-Huxley equations implemented with a thin film approximation of the neuron membrane. The computations of the membrane potential and currents, as well as that of the intra and extracellular potential fields, are performed at the same time, within a single finite element software. The neuron membrane model is validated by comparison with a NEURON simulation. It is shown that the finite element model is able to properly represent the neuron behavior in terms of membrane currents and potential. Moreover, it is demonstrated that an ideal measurement system model can be used, provided that the electronic recording system is adapted to the electrode-tissue interface impedance. A brief study of the influence of the relative position of the neuron and recording microelectrode on the recorded signal is presented. It is shown that the maximum recorded extracellular action potential is obtained when the electrode is placed below the neuron soma and hillock-initial segment areas.