The enhanced visual acuity and heightened motion detection found in deaf cats is because of reorganization of the brain area typically devoted to auditory function, reports a study published online this week in Nature Neuroscience. The findings provide insight into the plasticity that may occur in the brains of deaf people.
Previous studies of people who are deaf or blind have documented enhanced perceptual abilities in the remaining senses. It had been proposed that these enhanced abilities might be mediated by a reorganization of the part of the brain that would normally sub-serve the lost sense.
Stephen Lomber and colleagues have established a more causal link between enhanced visual abilities and reorganization of the auditory cortex in congenitally deaf cats. They found that when two specific areas of auditory cortex were deactivated, the deaf cats no longer had enhanced visual abilities. This is in comparison to hearing cats whose abilities were unaffected by this treatment.
Interestingly, the team discovered the area that sub-served the deaf cats’ enhanced visual localization typically sub-serves sound localization in hearing cats. Also, the area that was found to sub-serve the enhanced motion detection is adjacent to visual motion processing areas, implying that the enhanced visual abilities in deaf cats were not mediated in a distribution fashion by the entire auditory cortex, but by discrete regions.