Systems and techniques for controlling the stimulation of tissue. In one aspect, an apparatus includes an implantable stimulation device to elicit a response in a tissue by delivering one or more stimuli. The stimulation device includes a stimulus delivery element to deliver the one or more stimuli to elicit the response, a memory to store a range value identifying a range of values of a stimulation parameter relative to a first value, and a controller to control delivery of the stimuli by the stimulus delivery element in accordance with the range value. The stimulation parameter characterizes the stimuli to be delivered by the stimulation device.