Interhemispheric asymmetry of olfactory input dependent neuronal specification in the adult brain

The vertebrate brain is anatomically and functionally asymmetric. The left and right cerebral hemispheres harbor neural stem
cell niches at the ventricular-subventricular zone (V-SVZ) of the ventricular walls, where new neurons are continuously generated
throughout life. However, any interhemispheric asymmetry of neural stem cell niches remains unclear. We performed gene-trap
screens in adult zebrafish to identify genes that are differentially expressed in the two hemispheres and found that adult-born
neurons expressing the neural zinc-finger protein Myt1 exist predominantly in the left V-SVZ. This lateralization could be reversed
by left olfactory sensory deprivation–induced inactivation of Notch signaling. The olfactory behavioral preference for attractive
amino acids was also impaired by sensory deprivation of the left olfactory system, but not of the right olfactory system. Our findings
suggest that olfactory input generates interhemispheric differences in the fate of adult-born neurons in the zebrafish brain.