Devices, systems, and techniques are described for identifying stimulation parameter values based on electrical stimulation that induces dyskinesia for the patient. For example, a method may include controlling, by processing circuitry, a medical device to deliver electrical stimulation to a portion of a brain of a patient, receiving, by the processing circuitry, information representative of an electrical signal sensed from the brain after delivery of the electrical stimulation, determining, by the processing circuitry and from the information representative of the electrical signal, a peak in a spectral power of the electrical signal at a second frequency lower than a first frequency of the electrical stimulation, and responsive to determining the peak in the spectral power of the electrical signal at the second frequency, performing, by the processing circuitry, an action.