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How much does the adult brain weigh and how many neurons does it possess? 

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These findings show, for the first time, that inhibiting adult neurogenesis alters the circuitry of projection neurons in brain regions that receive new interneurons and points to a critical role for adult-born neurons in stabilizing a brain circuit that exhibits high levels of plasticity.
However, it remains to be determined how the microenvironmental elements support adult neurogenesis functionally and coordinate with each other.
The adult human brain thus harbours MPCs, which have the ability to develop into neurons and in doing this follow characteristic steps of neurogenesis as seen in the developing brain.
This study provides the first evidence in adult brain that NCAM180,140 varies in extent and location within neurons.
However, it is possible that brain size alone simply does not provide sufficient resolution on the question of how brain morphology and cognitive capacities coevolve.
It does not seem overly difficult to estimate directly the relationships among brain weight, intelligence, and fitness.
Open accessJournal ArticleDOI
Helena Frielingsdorf, H. Georg Kuhn 
7 Citations
We conclude that, to date, little is known with certainty about why new neurons are generated in the adult brain.

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