February 4, 2014
Brains On The Brain
Our brains are inherently complex. Many people think of the brain as a singular entity, that pink, squishy thing crammed inside our skulls that allows us to think and gives us insanely painful headaches when we eat ice cream too fast. The truth of the matter is that the brain, while able to be looked at as a singular portion of our bodies, is actually made up of billions of neurons that are all organized into various regions that control different actions – conscious and unconscious. It controls our breathing, how we move our arms and legs, our heart, blinking, and every other detail about our being. It is not a far stretch to say that the brain is the singular most important part of our bodies, as we would be nothing but an empty shell without it. Yet despite its definitive importance, there is a lot about the brain that we do not know. We know that the brain is divided into hemispheres, that each of these hemispheres controls different bodily functions and abilities. We know that the brain generates a bio-electrical current, and so much more, but we are still unclear about just how the brain is able to do what it does. How does it work? How do all of those neurons work together without getting in the way of each other? What is it that allows the various parts of our brains to work both together and independently, depending on the task at hand?
We do not have the answers to all of these questions just yet, but thanks to the work of professor Krishna Shenoy and his team from the Stanford School of Engineering we just might have be able to answer a few of them.
During an experiment designed to study how preparation helps the brain make fast and accurate movements for the design of prosthetic devices, the researchers used a new approach when examining their data, and that approach led them to some interesting findings that went beyond the range of the initial experiment. The researchers were studying the difference in brain signals between the command to act and to prepare in terms of arm motion, focusing on three specific places within the body. The arm muscles and two motor cortical regions in the brain that control arm motion. Muscle readings were simple enough, but the readings from the brain were a bit too much to handle conventionally. Each of the two regions of the brain were made up of more than 20 million neurons, far too many to probe individually, so they took readings from carefully chosen samples of between 100 and 200 individual neurons in each of those regions. They did this both while the arm was in motion and while it was preparing to be in motion, trying to understand and formulate the difference between the two. What they came to realize was that while the subject was “preparing” to move their arm, the brain was carefully balancing all activity changes of those neurons inside each region. While some were firing more quickly, others were slowed so that the entire population could broadcast a constant message to the muscles. Then, at the moment the arm went into motion, those population readings changed significantly, allowing them to document the changes. By looking at the data, the researchers were then able to correlate these changes at the population level to the flexing of the muscles, gaining a much clearer understanding of the differences in the brain’s commands.
The more we know about how our brains control the movement of our bodies, the better able researchers and engineers will be able to construct prosthetic limbs for patients suffering from either paralysis or amputation. This research could go a long way toward improving bionic limbs.
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