Apparatus and methods are described for increasing sensitivity of sensory nerves of a portion of a subject's body. A plurality of electrodes (22) are placed at respective locations upon a surface of the body portion. A computer processor (24) applies sets of electrical stimulation pulses to the respective locations upon the surface, via the electrodes. The computer processor receives respective inputs from the subject, via a user interface (26), each of the inputs corresponding to a respective one of the sets of electrical stimulation pulses, and being indicative of a location at which the subject sensed the set of electrical stimulation pulse as having been applied. In response to the inputs from the subject, the computer processor modulates parameters of the sets of electrical stimulation pulses that are applied to respective locations upon the surface of the body portion. Other applications are also described.