Credit: Kira Mosher, University of California, Berkeley
After a challenging day at work or school, sometimes it may seem like you are down to your last brain cell. But have no fear—in actuality, the brains of humans and other mammals have the potential to produce new neurons throughout life. This remarkable ability is due to a specific type of cell—adult neural stem cells—so beautifully highlighted in this award-winning micrograph.
Here you see the nuclei (purple) and arm-like extensions (green) of neural stem cells, along with nuclei of other cells (blue), in brain tissue from a mature mouse. The sample was taken from the subgranular zone of the hippocampus, a region of the brain associated with learning and memory. This zone is also one of the few areas in the adult brain where stem cells are known to reside.
Credit: Raunak Basu, University of Utah, Salt Lake City
The final frontier? Trekkies would probably say it’s space, but mapping the brain—the most complicated biological structure in the known universe—is turning out to be an amazing adventure in its own right. Not only are researchers getting better at charting the brain’s densely packed and varied cellular topography, they are starting to identify the molecules that neurons use to connect into the distinct information-processing circuits that allow all walks of life to think and experience the world.
This image shows distinct neural connections in a cross section of a mouse’s hippocampus, a region of the brain involved in the memory of facts and events. The large, crescent-shaped area in green is hippocampal zone CA1. Its highly specialized neurons, called place cells, serve as the brain’s GPS system to track location. It appears green because these neurons express cadherin-10. This protein serves as a kind of molecular glue that likely imparts specific functional properties to this region. 
We all know that exercise is important for a strong and healthy body. Less appreciated is that exercise seems also to be important for a strong and healthy mind, boosting memory and learning, while possibly delaying age-related cognitive decline . How is this so? Researchers have assembled a growing body of evidence that suggests skeletal muscle cells secrete proteins and other factors into the blood during exercise that have a regenerative effect on the brain.
Now, an NIH-supported study has identified a new biochemical candidate to help explore the muscle-brain connection: a protein secreted by skeletal muscle cells called cathepsin B. The study found that levels of this protein rise in the blood of people who exercise regularly, in this case running on a treadmill. In mice, brain cells treated with the protein also exhibited molecular changes associated with the production of new neurons. Interestingly, the researchers found that the memory boost normally provided by exercise is diminished in mice unable to produce cathepsin B.
Caption: Cocoa beans and cocoa powder, which are rich in antioxidant compounds called flavanols. Credit: Mars Inc.
As we get older, remembering new stuff—an updated computer password or the name of that person whom we met last night (or was it two nights ago?)—can bring a busy day to a head-scratching halt. But are these “senior moments” just something that we have to accept? Maybe not.
In a study published in Nature Neuroscience, a research team partially funded by NIH has provided evidence that changes in a specific brain region are associated with age-related memory loss . And they found that they could reverse this loss by boosting activity in this part of the brain, called the dentate gyrus. What’s especially interesting is that this boost came from a drink that was specially formulated to be rich in flavanols, a group of antioxidant compounds found in cocoa beans. Sounds like every chocolate lover’s dream! But let’s drill down a little deeper.