THE potential for plasticity of the developing mammalian visual system has been the subject of several investigations1,2. I have now explored the plastic relationship between different sensory modalities. The rodent superior colliculus was chosen as the model as it receives overlapping visual, somatic and auditory inputs3,4. Electrophysiological comparison of dark-reared and normal rats suggests that the rat's superior colliculus is susceptible to effects of sensory deprivation during its postnatal development.