The human brain is made up of tens of billions of neurons, brain cells that act as information messengers, transmitting and receiving chemical and electrical signals. These messages are received by branch-like cell structures called dendrites after traveling across synapses, the tiny gap between neurons. Now, researchers in NIA’s Intramural Research Program have shown in mice that a protein, PGC-1alpha, may play an important role in forming and maintaining healthy dendrites and synapses in the hippocampus--the brain region important to learning and memory.