Competing Brain Cells Lead to Memory Development

Brain cells may aid alzheimer’s, autism and schizophrenia

(RxWiki News) Much like advanced electronic devices with large systems of circuits and wires, our brain is a complicated machine. But unlike programming a remote control, the brain can do work itself -- shaping and refining memories unassisted.

In fact scientists have recently demonstrated that memory circuits in the brain refine themselves in living organisms through competition between two distinct types of cells.

University of Michigan Health System researchers said the discovery could be a step forward toward the causes of neurological disorders associated with abnormal brain circuits such as Alzheimer’s disease, autism and schizophrenia.

"Talk to your doctor about treatments for diseases associated with abnormal brain circuits."

Most research about how the brain is wired is derived from studying sensory and motor systems. Less is understood about mechanisms that organize neural circuits used in higher brain function such as memory and learning.

Senior author Dr. Hisashi Umemori, M.D., Ph.D., assistant research professor at U-M’s Molecular and Behavioral Neuroscience Institute and assistant professor of biological chemistry at the U-M Medical School said brain cells grow and extend along pathways to link different parts of the brain, and as the brain develops, the connections fine-tune and become more efficient.

Problems with this refinement process in the brain might be responsible for certain neurological disorders.

Researchers used genetically modified mice so that neurons of interest purposefully could be switched off. The team focused on an important connection between the hippocampus, which is crucial for learning and memory, and the cerebral cortex, which is key for perception and awareness.

They deactivated about 40 percent of the neurons in the connection and watched over several days as the brain eliminated the inactive neural connections and kept only the active ones. Another part of the study demonstrated that if all the neurons were deactivated, their connections were not eliminated.

Researchers concluded the brain had a way of determining which connections are better than others among a group of neurons, but if a pair is in competition, none will be eliminated when all of them are equally bad.

The team also examined part of the hippocampus called the dentate gyrus, which is only one of two areas of the brain that continues to generate new neurons throughout life. They found a second distinct type of competition: newborn cells competing with mature cells.

When the dentate gyrus’ ability to make new cells was blocked, the elimination quit and the brain kept the existing cells even if they were no longer active.

Funding was provided by the U-M Center for Organogenesis, the Ester A. & Joseph Klingenstein Fund, the Edward Mallinckrodt Jr. Foundation, the March of Dimes Foundation, the Whitehall Foundation and the National Institutes of Health.

The findings are published in the journal Neuron.

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Review Date: 
June 23, 2011