Wiring New Neurons with Old Circuits

  • Pierre-Marie LledoEmail author


The brain derives much of its function from its ability to adapt to tasks on a wide range of time scales, from milliseconds to days, weeks, and months. This adaptability at multiple time scales is found across all brain areas, from cognitive areas all the way to the peripheral areas, in which sensory information is encoded so as to facilitate the subsequent extraction of relevant information. The adaptability of the brain is achieved through multiple morphological and physiological changes occurring at all levels: from molecules, to spines, and to dendrites and axons. It is clear today that brain plasticity also operates at the level of entire cells. In at least two areas of the adult brain, new neurons are constitutively generated throughout life and form an integral part of the networks. Because the capacity of the adult brain to rewire itself depends on external influences, ongoing neuronal production represents also a plastic mechanism by which brain performance can be optimized according to the prevailing environment. However, it remains unclear when and why brain performance has to be optimized.

This chapter focuses on the functional issues linked to neurogenesis in the olfactory system. After outlining the processes of adult neurogenesis in the olfactory system and discussing their regulation by various factors, I consider how existing circuits can continue to work in the face of constant arrivals and departures of cells and explore the possible functional role of adult-born neurons in the host microcircuit. Concentrating exclusively on mammalian systems, I demonstrate throughout this chapter that adult neurogenesis is a plastic mechanism by which brain performance can be optimized to cope with changing environment or internal state.


Green Fluorescent Protein Granule Cell Olfactory Bulb Projection Neuron Adult Neurogenesis 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



I apologize to those authors whose references, although relevant to this subject, have not been included in this review for reasons of space constraints. My laboratory is supported by the Fondation pour la Recherche Médicale (Équipe FRM), by the life insurance company “AG2R-La-Mondiale,” and by Ecole des Neurosciences de Paris (ENP).


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© Springer 2011

Authors and Affiliations

  1. 1.Laboratory for Perception and Memory, Department of NeuroscienceInstitut PasteurParisFrance
  2. 2.CNRS, URA2182ParisFrance

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