A system may be configured to sense local field potentials (LFPs) from electrodes placed in epidural space near the spine of a patient. The system may be configured to analyze the sensed LFPs and determine a change in a state of the patient, such as a physiological state of the patient. The system may use such analysis to update and/or suggest parameters for delivery of electrical stimulation therapy. The system may further be configured to analyze LFPs in a frequency domain by applying a wavelet transform or other transform to sensed LFPs.