Recruitment of the auditory cortex in congenitally deaf cats by long-term cochlear electrostimulation

In congenitally deaf cats, the central auditory system is deprived of acous tic input because of degeneration of the organ of Corti before the onset of hearing. Primary auditory afferents survive and can be stimulated electric ally. By means of an intracochlear implant and an accompanying sound proces sor, congenitally deaf kittens were exposed to sounds and conditioned to re spond to tones. After months of exposure to meaningful stimuli, the cortica l activity in chronically implanted cats produced field potentials of highe r amplitudes, expanded in area, developed Long Latency responses indicative of intracortical information processing, and showed more synaptic efficacy than in naive, unstimulated deaf cats. The activity established by auditor y experience resembles activity in hearing animals.