The design and application of three speaker-based stimulating devices for cutaneous stimulation in anesthetized and awake animals

Those wishing to study neuronal plasticity in sensory systems are confronted by the need to deliver equivalent stimuli to the organism at time intervals separated by hours, days or months. This problem is particularly acute in the somatosensory system where delivering an equivalent stimulus generally requires a second physical contact with the same point on a geometrically complex surface. This requirement is difficult to fulfill. We have designed two stimulators that avoid or minimize the importance of this requirement by obviating the need for the stimulator to be at a fixed distance from the skin. As well, we have redesigned a system for whisker stimulation originally proposed by Simons. The first stimulator is appropriate for experiments in anesthetized animals; the surface to be stimulated is immersed in water warmed to body temperature and the tactile stimulus is generated as an hydraulic pulse. The second uses a high velocity pulse of air shaped so that it can be transmitted significant distances without attenuation. The redesign of the Simons' vibrissa stimulator provides larger amplitude displacements and lower controlling voltages more readily generated by equipment normally found in laboratories. We also described the design of a chamber for restricting the awake rat during chronic study and the electrodes used for recording and for delivery of drugs in awake animals held in such a chamber.