Magavi SS, Mitchell BD, Szentirmai O, Carter BS, Macklis JD. 2005. Adult-born and preexisting olfactory granule neurons undergo distinct experience-dependent modifications of their olfactory responses in vivo. The Journal of neuroscience : the official journal of the Society for Neuroscience. 25(46):10729-39. Pubmed: 16291946


Neurogenesis continues throughout adulthood in the mammalian olfactory bulb and hippocampal dentate gyrus, suggesting the hypothesis that recently generated, adult-born neurons contribute to neural plasticity and learning. To explore this hypothesis, we examined whether olfactory experience modifies the responses of adult-born neurons to odorants, using immediate early genes (IEGs) to assay the response of olfactory granule neurons. We find that, shortly after they differentiate and synaptically integrate, the population of adult-born olfactory granule neurons has a greater population IEG response to novel odors than mature, preexisting neurons. Familiarizing mice with test odors increases the response of the recently incorporated adult-born neuron population to the test odors, and this increased responsiveness is long lasting, demonstrating that the response of the adult-born neuron population is altered by experience. In contrast, familiarizing mice with test odors decreases the IEG response of developmentally generated neurons, suggesting that recently generated adult-born neurons play a distinct role in olfactory processing. The increased IEG response is stimulus specific; familiarizing mice with a set of different, "distractor" odors does not increase the adult-born neuron population response to the test odors. Odor familiarization does not influence the survival of adult-born neurons, indicating that the changes in the population response of adult-born neurons are not attributable to increased survival of odor-stimulated neurons. These results demonstrate that recently generated adult-born olfactory granule neurons and older, preexisting granule neurons undergo contrasting experience-dependent modifications in vivo and support the hypothesis that adult-born neurons are involved in olfactory learning.

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Photo of Jeffrey D. Macklis

Jeffrey Macklis investigates molecular controls and mechanisms over neuron subtype specification, development, diversity, axon guidance-circuit formation, and pathology in the cerebral cortex. His lab seeks to apply developmental controls toward brain and spinal cord regeneration and directed differentiation for in vitro mechanistic modeling using human assembloids.

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