The "birth" of neurons has been witnessed in a live brain for the first time.
Neurons provide the crucial mechanism that allows the brain to operate; 'born' in the hippocampus, they are responsible for processing memories and keeping related, but separate, memories distinct from one another.
What wasn't always clear is how -- or even if -- new neurons can be made in the brain. Though it now seems clear that they are, that process had never been witnessed first hand -- the brain is complex and delicate, and neurons are extremely small and intricate.
To get around those restrictions, a team at Columbia University Medical Center in New York used several techniques to observe the birth of the neurons -- first implanting a miniature microscope into the brains of mice, and then chaning the mice so that their new neurons would glow enough to be picked up by that device. Once prepared, the mice were placed on a treadmill and ran while they experienced slightly different sights and smells, and were given electric shocks to create an association between the stimuli and the unpleasant experience.
When the neurons were then 'turned off', the mice were no longer able to tell between cues that were neutral and cues that were unpleasant. This, the team says, suggests that the new neurons were responsible for telling the difference between similar memories.
This result was replicated when the mice were placed into identical chambers, in which they had received shocks and rewards at different times.
Because the skill responsible for separating memories is reduced in people with anxiety disorders, the team hope that their research will prove useful for further investigations of depression and anxiety. Many antidepressants "stimulate the production of new hippocampus neurons", the team says, so their new discovery may provide new insight into the link between the neurons and mental illness.
