Measuring a neural response to a stimulus comprises applying an electrical stimulus, then imposing a delay during which the stimulus electrodes are open circuited. During the delay, a neural response signal present at sense electrodes is measured with a measurement amplifier, while ensuring that an impedance between the sense electrodes is sufficiently large that a voltage arising on the sense electrode tissue interface in response to the stimulus is constrained to a level which permits assessment of the neural response voltage seen at the sense electrode. For example the input impedance to the measurement amplifier (Z IN ) can be (Formula (I)), where Z C is the sense electrode(s) constant phase element impedance, V s1 V s2 is the differential voltage arising on the sense electrode tissue interface, and V E is the neural response voltage seen at the sense electrode.
