Energy demands limit our brains’ information processing capacity

Our brains have an upper limit on how much they can process at once due to a constant but limited energy supply, according to a new UCL study using a brain imaging method that measures cellular metabolism. The study, published in the Journal of Neuroscience , found that paying attention can change how the brain allocates its limited energy; as the brain uses more energy in processing what we attend to, less energy is supplied to processing outside our attention focus. Explaining the research, senior author Professor Nilli Lavie (UCL Institute of Cognitive Neuroscience) said: "It takes a lot of energy to run the human brain. We know that the brain constantly uses around 20% of our metabolic energy, even while we rest our mind, and yet it's widely believed that this constant but limited supply of energy does not increase when there is more for our mind to process. "If there's a hard limit on energy supply to the brain, we suspected that the brain may handle challenging tasks by diverting energy away from other functions, and prioritising the focus of our attention. "Our findings suggest that the brain does indeed allocate less energy to the neurons that respond to information outside the focus of our attention when our task becomes harder. This explains why we experience inattentional blindness and deafness even to critical information that we really want to be aware of." The research team of cognitive neuroscientists and biomedical engineers measured cerebral metabolism with a non-invasive optical imaging method.