Much of the revival in deal activity reflects a build-up in the capital that firms hold.

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The idea that more brain cell activity could lead to more amyloid-beta build up is an exciting, if sobering, finding.

FORBES: Wandering into Alzheimer's: Could Your Thoughts Reduce Your Risk?

It is not clear, for example, how such a large position was allowed to build up over the three-month period that the activity was said to be taking place.

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It is thought that a build up of chemicals like dopamine suppresses the activity of the brain's natural painkillers - the endogenous opioids.

BBC: Gene controls pain threshold