The electrical activity occurring in our brains when we're not really paying attention takes the form of alpha waves. By using a new technique to examine these waves, Dr. Kyle Mathewson, Beckman Institute Postdoctoral Fellow at the University of Illinois, and his colleagues are learning about how awareness affects the brain's ability to process external stimuli. In fact, their new research suggests that alpha waves may actually influence what we see and what we don’t see. If we control these waves with the help of a little electrical stimulation applied directly to our brains, we might actually improve our vision.
To begin their study, the researchers selected 16 participants and used an MRI scan to map their brains. Next, the researchers used electroencephalography (EEG) to record the electrical activity along the scalp. Because there’s a hard skull between the EEG sensors and the brain, it can be extremely difficult to see exactly where signals originate, so the researchers turned to a new technique developed by Gabriele Gratton and Monica Fabiani, professors of psychology and authors of the study. Their new technique is called EROS (event-related optical signals), and it uses near-infrared light passed through optical fibers to measure changes in the active areas of the cerebral cortex. EROS essentially examines how light is scattered, thus pinpointing activity within the brain.
"[EROS] exploits the fact that when neurons are active, they swell a little, becoming slightly more transparent to light,” explained Fabiani and Gratton in a press release. “This allows us to determine when a particular part of the cortex is processing information, as well as where the activity occurs." Using EROS, the researchers measured activity in the brain and mapped the origin of alpha waves.
What did they discover after experimenting on the 16 participants? Alpha waves are produced in the cuneus, located in the occipital lobe, a region of the brain that processes visual information and is located at the back of the skull. Because alpha waves originate in the occipital lobe, they may inhibit what you are able to process visually, making it hard for you to see something unexpected. So when you relax and your mind rests, the increased number of alpha waves quite literally blocks what you are able to see.
However, if you force yourself to focus (pay attention!) and concentrate more fully on what you are experiencing, you can regain control of your mind and therefore of what you see. In such cases, the executive function of your brain, which is carried out in the frontal lobe, puts a brake on the alpha waves coming from the back of your brain, and this in turn allows you to see things that you might have missed in a more relaxed state.
"Knowing where the waves originate means we can target that area specifically with electrical stimulation," Mathewson said. As he imagines it, someday people might be given moment-to-moment feedback — electrical stimulation — to prevent straying attention. For instance, while driving a car, a driver might be stimulated whenever they are not paying attention to the road ahead. Students, pilots, and equipment operators also might be monitored and stimulated whenever they need to focus. Sounds creepy now, but when you avoid driving into a truck, you might think otherwise... no?
Source: Mathewson KE, Beck DM, Ro T, et al. Dynamics of Alpha Control: Preparatory Suppression of Posterior Alpha Oscillations by Frontal Modulators Revealed with Combined EEG and Event-related Optical Signal. Journal of Cognitive Neuroscience. 2014.