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Regeneration of dopaminergic neurons

 

To examine how adult neurogenesis in the olfactory bulb contributes to regeneration after circuit injury, we performed acute DAergic neuronal loss by injecting 6-hydroxydopamine (6-OHDA). We found that a 6-OHDA treatment strongly decreases the number of neurons expressing the enzyme tyrosine hydroxylase (TH) nearby the injected site in the olfactory bulb. Despite this neuronal loss, the number of TH+ interneurons was restored two months later. This rescue resulted at least in part from enhanced recruitment of immature neurons in the lesioned glomerular layer area, but not elsewhere. During this period of circuit restoration, we found that the integration of lentivirus-labeled adult-born neuron was biased: newly-formed neurons were preferentially incorporated into glomerular circuits of the lesioned area at the expense of other areas. Remarkably, the restoration of glomerular circuits was also accompanied by behavioral rehabilitation. While acute 6-OHDA treated mice transiently lost innate responses towards social and non-social olfactory cues, mice exhibited unchanged innate responses two months later. Adult neurogenesis not only replenished the population of TH+ neurons in the glomerular layer after chemical DA depletion, but it also restored olfactory sensory processing. Thus, this study reports a critical role for adult neurogenesis in behavioral recovery after brain injury.

 

 

Source

Lazarini et al. (2014), Adult neurogenesis restores dopaminergic neuronal loss in the olfactory bulb. J Neurosci. 34(43): 14430-42.

 

 

Mental states control the integration of new neurons in the adult brain

 

Although it has been known for several years that the adult brain is capable of producing new neurons, how these neurons are integrated into existing, functional nerve circuits has hitherto remained a mystery. Scientists at the Institut Pasteur and the CNRS have just shown that new neurons set up a denser network of connections with the rest of the brain in contexts of active (as opposed to passive) motivation and learning. It is therefore mental states, rather than the type or diversity of the sensory environment, that determine the functional activity of adult-born neurons. These results were published in the PNAS journal on September 1, 2014.

 

Source

Lepousez G, Nissant A, Bryant AK, Gheusi G, Greer CA, Lledo PM. (2014), Olfactory learning promotes input-specific synaptic plasticity in adult-born neurons. Proc Natl Acad Sci U S A. 2014 Sep 23;111(38):13984-9. doi: 10.1073/pnas.1404991111. Epub 2014 Sep 4.

 

 

 

We have recently done some work using Andor digital mirror devices (DMDs) to specifically stimulate ChR2 expressing adult-born neurons in slice. 

 

Here is a link to a technical note on their website describing this technique:

http://www.andor.com/learning-academy/using-light-to-demonstrate-the-plasticity-behind-memory-case-study

Updated on 27/07/2015

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