Scans--CAT, MRI, and PET--have become critically important tools for physicians diagnosing disease, as well as scientists studying brain function. However, they yield only snapshots of an organ that, neuroscientists now understand, continually changes.
X-ray CAT scans reveal only static pictures of brain structures. And magnetic resonance imaging (MRI) scans and positron emission tomography (PET) scans, which use, respectively, magnetic fields and radioactive tracers, only indirectly reveal changes in the activity of brain regions by detecting blood-flow changes that reflect increased activity.
Now, Duke neurobiologist Miguel Nicolelis and his colleagues have demonstrated that they can directly "see" the intricate, detailed patterns of electrical activity across a living "brainscape," as the brain changes from moment to moment.
Using hair-thin microelectrodes and computer analysis of brain signals, they have shown in rats that they can distinguish fleeting changes in communication among brain structures in animals that are awake, then fall asleep and move through different sleep stages. The researchers believe their analytical technique will enable new understanding and treatment of diseases including epilepsy, Alzheimer's disease, and schizophrenia, according to their article in a December issue of the Journal of Neuroscience.
The researchers extended brain-monitoring technology that they used to enable monkeys to control robot arms using only their brain signals. Nicolelis and his colleagues published a report on that technology in 2003. A new imaging technique is critical if scientists are to explore the new paradigm being espoused by Nicolelis and his colleagues of the brain as a dynamic, constantly changing organ.
"One of the Holy Grails of neurobiology has been the neural 'code' by which the brain processes information," says Nicolelis. "Now we can say that there is no such thing as a single neural code, because the code is continuously changing according to the internal state of the brain, and according to the strategy the animal selects to search the environment."