Cognition & plasticity
As detailed in Disterhoft et al. (1994) [see review 2., at http://www.utdallas.edu/~tres/neuro_pubs.html), the calcium hypothesis of aging has considerable predictive power in assessing learning related changes both in the brain and in behavior. Calcium is a ubiquitous intracellular signal, and calcium homeostasis is impaired by the aging process.