In the adult cat, after an early degeneration (hereditary deaf white cats) or surgical removal of auditory receptors, it is possible to record visual evoked responses on the primary auditory cortex. The appearance of such potentials depends on two conditions: a complete (bilateral) and early (first postnatal month) deafferentation. This can be explained by an early multi-afferentation of the primary cortical areas. The early suppression of the primary modality may keep the other modalities still working in the adult.