Abstract: Methods, systems and devices for monitoring a target in a neural system involve delivering inputs to and recording output responses from the neural system and obtaining I/O characterizations of the neural system both before and during or after a change is introduced to the system, for example, a change associated with a stem cell therapy. Baseline and therapeutic I/O characterizations are compared, and interpretations of the results of the comparison may be used to adjust some aspect of the therapy to facilitate it or control it. An implantable neurostimulator with the capability of delivering electrical stimulation to an electrode and of measuring and recording responses sensed from electrodes, where the electrodes are strategically positioned at or near the target, can be used to deliver an electrical stimulation input and record the output responses for the I/O characterizations.