The part of the brain involved in visual processing (the visual cortex) is like a television screen that creates a picture out of a collection of dots or “pixels”. Each brain pixel is composed of a column full of neurons that act together. Unstimulated columns flicker between being electrically active and sensitive to stimuli (“On”) or being inactive and resistant to electrical activity (“Off”). If visual information (a stimulus) hits a visual column that is “On”, then the information is registered as a large electrical spike. But if visual information hits a column when it is “Off”, then it might not be registered at all.
Engel and Shi, in collaboration with Stanford University Professors Kwabena Boahen and Tirin Moore, and University of Washington Assistant Professor Nicholas A. Steinmetz, found that when monkeys are paying attention to a stimulus, the waves get shorter and choppier. “On” and “Off” states blink through visual cortex columns driven by this stimulus more quickly and in a smaller area than when the animal’s attention is elsewhere. But why would an awake and attentive brain want to cycle its columns off and miss information? Engel has a few hypotheses. She says, “keeping neurons in the ‘On’ state all the time is energetically costly. Another reason is that if we were always receptive to information, we may become overwhelmed; the ‘Off’ state could help suppress irrelevant information.”
The discovery that electrical noise changes patterns with different brain states could help researchers understand brain responses to drugs and disease. And since primate brains are very good at processing visual information, machine learning researchers might borrow its cleverly structured noise tricks to improve artificial brains.
About Cold Spring Harbor Laboratory
Founded in 1890, Cold Spring Harbor Laboratory has shaped contemporary biomedical research and education with programs in cancer, neuroscience, plant biology and quantitative biology. Home to eight Nobel Prize winners, the private, not-for-profit Laboratory employs 1,100 people including 600 scientists, students and technicians. For more information, visit www.cshl.edu
SOURCE Cold Spring Harbor Laboratory
