In the zebrafish brain, neurons born during adulthood in the ventricular–subventricular zone (V–SVZ) of the ventricular wall in each hemisphere migrate towards and become incorporated into the olfactory bulb. Kishimoto et al. examined whether interhemispheric asymmetry exists between these neural stem niches, as a seemingly lateralized circuit connects the olfactory bulb to higher brain regions. The authors found that expression of the neural zinc-finger protein Myt1 was largely confined to adult-born neurons in the left V–SVZ. Moreover, they showed that left but not right olfactory sensory deprivation eliminated this lateralized expression pattern and impaired the behavioural response to a normally attractive amino acid mixture. These results indicate that interhemispheric differences in adult-born neurons may be induced by olfactory inputs and may result in functional asymmetry in neurons in the olfactory bulb.