Neuroscience. Stem cells hear call of injured tissue

In animal models, injected stem cells travel to tissue injured by stroke, Alzheimer's-like plaques, contusions, or spinal cord bruises, sometimes traversing long distances. Several teams reported these surprising results this month at the Society for Neuroscience annual meeting. No one knows exactly how stem cells detect these different kinds of damage, but researchers hope that the cells' migratory powers can be harnessed to either replace dead tissue or deliver therapeutics right where they're needed.     

Neuroscience. New brain cells prompt new theory of depression

No one knows what causes depression, although many neuroscientists blame an imbalance of brain chemicals, so-called neurotransmitters, especially those that affect the brain's pleasure responses. Now a few neuroscientists are converging on a radical, but complementary, theory: that depression may be caused by a lack of new cell growth in the brain. The recent discovery that the brain keeps producing neurons into adulthood has given this highly speculative theory at least one leg to stand on.