Finding Structure in the Brain’s Static
While sleeping, the whole brain flow through long, slow waves of electrical activity, like waves on a calm ocean. Scientists call that state of consciousness “slow wave sleep.” Awakening alters the pattern of electrical activity into something that resembles random noise. Yet Cold Spring Harbor Laboratory (CSHL) Assistant Professor Tatiana Engel, Postdoctoral Fellow Yianling Shi, and their collaborators found there are patterns in the noise.
Looking at the visual processing region of a monkey brain, they found smaller, quicker, more localized versions of the large rolling sleep waves. The shapes and dynamics of these local waves connect to how attentive that part of the brain is. The researchers believe that the wave patterns offer a vital hint to comprehending anesthesia, attention, and sleep.
The visual cortex, the part of the brain related to visual processing, is like a television screen that creates an image out of a collection of dots or “pixels.” Each brain pixel is made up of a column packed with neurons that act all together.
Unstimulated columns flicker between being sensitive and electrically active to stimuli (” On”) or being inactive and resistant to electrical activity (” Off”). If visual information (a stimulus) strikes a visual column that is “On,” then the information is registered as a huge electrical spike. However if visual information strikes a column when it is “Off,” after that it might not be registered at all.
Engel and Shi, in cooperation with Stanford University Professors Kwabena Boahen and Tirin Moore, and University of Washington Assistant Professor Nicholas A. Steinmetz, discovered that when monkeys are taking notice of a stimulation, the waves get much shorter and choppier. “On” and “Off” states blink through visual cortex columns driven by this stimulus faster and in a smaller area than when the animal’s attention is elsewhere.
However, why would an attentive and awake brain intend to cycle its columns off and miss out on information? Engel has a handful of hypotheses. She claims, “keeping neurons in the ‘On’ state regularly is energetically damaging. Another reason is that if we were constantly receptive to information, we might end up being overwhelmed; the ‘Off’ state can assist subdue irrelevant information.”
The finding that electrical noise changes patterns with different brain states might aid researchers comprehend brain responses to drugs and disease. And given that primate brains are very good at processing visual information, machine learning researchers might borrow its intelligently structured noise tricks to boost artificial brains.
Read the original article on Medical Xpress.
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