"With a specific MRI methodology called 'Diffusion Imaging MRI,' we can investigate the microstructure of the tissue without actually cutting into it. We can measure how much capacity our brain has to change structurally, what our memory reserve is and where that happens," said Dr. Yaniv Assaf of Tel Aviv University's Department of Neurobiology.
Scientists used to believe that the brain took days or weeks to change its microstructure. But Assaf's new observations show that the microstructure can change in mere hours.
"It gives us a quantifiable measure of the plasticity of each individual brain. It's possible that before a person experiences any memory loss, the plasticity is affected - that is, the ability of one's brain to adapt to change. A lack of ability for change in the brain could mean susceptibility to dementia. Now, we have the means to monitor this ability," he said.
In order to track changes in the brain, Assaf developed a study that focused on spatial learning and memory.
"Usually, scientists distinguish between functional and structural plasticity," he said.
Functional plasticity refers to neuronal activity in the brain, while structural plasticity refers to the physical shape of the brain itself.
First, study volunteers were scanned by Diffusion Imaging MRI. Then, they were asked to play two hours of a race-track video game, going over the same virtual race track 16 times.
"This measured a special form of memory - spatial memory. Each time they circled the track, the time they took to complete it decreased. At the end of the two hours, we put them back into the MRI to see the difference," said Assaf.
Assaf and his team saw a marked change measured by Diffusion Imaging MRI in the characteristics of brain microstructure. The memorization of the virtual race-track affected the hippocampus, motor and visual areas of the brain.
"The most striking thing about this study is that it shows structural plasticity happening in only two hours. This changes what we think structural plasticity is. It shows that memory is rapidly changing the structure of the cells, and that may lead to a lasting effect on the brain," he said.
According to Assaf, most of the research on Alzheimer's disease and dementia focuses on its aftereffects. He believes Diffusion Imaging MRI could be used for early detection of the disorder.
The study has been presented at the Annual Meeting of the Human Brain Mapping Organization in San Francisco.