The functional significance of newly born neurons integrated into olfactory bulb circuits.

Masayuki Sakamoto,Ryoichiro Kageyama,Itaru Imayoshi

doi:10.3389/fnins.2014.00121

Masayuki Sakamoto, Ryoichiro Kageyama + Show 1 more

Open Access

https://doi.org/10.3389/fnins.2014.00121

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Abstract

The olfactory bulb (OB) is the first central processing center for olfactory information connecting with higher areas in the brain, and this neuronal circuitry mediates a variety of odor-evoked behavioral responses. In the adult mammalian brain, continuous neurogenesis occurs in two restricted regions, the subventricular zone (SVZ) of the lateral ventricle and the hippocampal dentate gyrus. New neurons born in the SVZ migrate through the rostral migratory stream and are integrated into the neuronal circuits of the OB throughout life. The significance of this continuous supply of new neurons in the OB has been implicated in plasticity and memory regulation. Two decades of huge investigation in adult neurogenesis revealed the biological importance of integration of new neurons into the olfactory circuits. In this review, we highlight the recent findings about the physiological functions of newly generated neurons in rodent OB circuits and then discuss the contribution of neurogenesis in the brain function. Finally, we introduce cutting edge technologies to monitor and manipulate the activity of new neurons.

Highlights

It was believed that the adult mammalian brain is incapable of producing new neurons
Striatum neurogenesis is reduced in patients with Huntington’s diseases. These results indicate that adult neurogenesis in humans has a unique pattern, and that these neurons derived from subventricular zone (SVZ)/lateral ventricles might be involved in brain functions such as cognition and motor coordination
Relevant increase of new neurons occurs in male mice when they interact with their postnatal offspring (Mak and Weiss, 2010). This increase of neurogenesis mediated by prolactin appears to depend on the odor of their offspring and is involved in offspring recognition (Mak and Weiss, 2010). These results indicate that olfactory bulb (OB) neurogenesis is really related to sexual and maternal behaviors, suggesting that neurogenesis plays an important role in such pheromone-associated innatelyprogrammed behaviors

Summary

Introduction

It was believed that the adult mammalian brain is incapable of producing new neurons. Long-term genetic labeling analysis revealed that the majority of GCs are replaced by newly generated neurons during adult life (Imayoshi et al, 2008). This time window overlaps with the period when newly generated neurons make synapses with pre-existing neurons, suggesting that synaptic inputs play a crucial role in the selection of adult born GCs (Kelsch et al, 2008; Yokoyama et al, 2011).

Results

Conclusion