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From birdsong to neurodegenerative diseases
1/27/14

The fitness benefits of brain excercise

Time singing

This research also raises distant hopes regarding brain training. “It’s clear that the propensity to develop Alzheimer’s disease is negatively correlated with intellectual activity: the more intense it is, the more active circuits are retained and the more we delay the phenomena of degeneration. We also know that during growth, we overproduce an enormous quantity of neurons: when we are born, we have almost 10 times more neurons than when we reach adulthood: 80 to 90% of them will disappear during ontogeny. Strong experimental evidence suggests that those that remain alive are those that made nerve connections, that became functionally active”.

It is therefore the electrical activity of the neurons – resulting from the activity of the brain– that keeps these neurons alive and prevents their disappearance in young animals. Similarly adult neurogenesis produces neurons, of which 50 to 80 % disappear within 15 days; only a tiny minority will integrate functional circuits. The fact of learning new facts or skills, of having complex mental activities (playing chess, reading, etc.), will, in all likelihood, maintain alive some of these neurons. “By extrapolating what we have learnt through animal models, we could possibly in the future help maintaining a more functional brain structure by stimulating neural activity in adulthood and maintain during ontogeny neurons and connections that would otherwise disappear. The environment to which we are exposed can modulate the survival of neural regions and their connections”.

Is there anything in all the work on neuroplasticity in canaries that relates to man? Professor Balthazart points out that links between this type of work and man are always indirect. For the moment, there are no direct applications in humans. “If we talk about neurogenesis, then we are automatically talking about stem cells, which are multiplying through divisions and, at one point, become postmitotic and differentiate into neurons. A great deal of research has been done on mammals to study the mechanisms that control this differentiation into neurons and we have been able to establish cell lines and differentiate them in vitro into neurons that could then be reinjected into,brains. Researchers have successfully produced dopamine neurons to be reinjected into zones that are innervated by dopamine neurons to control motor function that are degenerating in the brains of patients with Parkinson’s disease .This treatment worked quite well in a Parkinson’s model in rats. On the other hand, results from clinical trials carried out on humans are quite mixed: improvements are only temporary; the reinjected neurons do not survive very long".

Other studies examine the problems of spinal cord lesions following traumatic accidents and attempt to restore connections by injecting stems cells, young neurons or axonal growth factors in the lesion. “But, obviously, these experiments do not copy exactly what happens in canaries, all procedures must be adapted to what happens in humans. There is no song control area in man, even though there is a very strong analogy between the areas that control song in canaries and those that control speech in man: the Wernicke and Broca areas”.

“The brain is the final frontier in biology. Barack Obama has just launched a highly ambitious programme (BRAIN)(2) to better understand the brain and better treat its pathologies because the brain is the cause of approximately one third to 40 % of work incapacity worldwide. And with the ageing population, this will become an increasing source of concern...”, concludes Jacques Balthazart.

(2) Brain Research through Advancing Innovative Neurotechnologies, http://www.nih.gov/science/brain/

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