Better olfactory performance and larger olfactory bulbs in a mouse model of congenital blindness.

It is well established that early blindness results in enhancement of the remaining non-visual sensory modalities accompanied by functional and anatomical brain plasticity. While auditory and tactile functions have been largely investigated, the results regarding olfactory functions remained less explored and less consistent. In the present study, we investigated olfactory function in blind mice using three tests: the buried food test, the olfactory threshold test and the olfactory performance test. The results indicated better performance of blind mice in the buried food test and odor performance test while there was no difference in the olfactory threshold test. Using histological measurements, we also investigated if there was anatomical plasticity in the olfactory bulbs, the most salient site for olfactory processing. The results indicated a larger volume of the olfactory bulb driven by larger glomerular and granular layers in blind mice compared to sighted mice. Structural plasticity in the olfactory bulbs may underlie the enhanced olfactory performance in blind mice.