The first comprehensive map of mouse brain activity has been unveiled by a large international collaboration of neuroscientists.\u00a0<\/p>\n
Researchers from the International Brain Laboratory<\/a> (IBL), including MIT neuroscientist Ila Fiete<\/a>, published their open-access findings today in two<\/a> papers<\/a> in Nature, revealing insights into how decision-making unfolds across the entire brain in mice at single-cell resolution. This brain-wide activity map challenges the traditional hierarchical view of information processing in the brain and shows that decision-making is distributed across many regions in a highly coordinated way.<\/p>\n \u201cThis is the first time anyone has produced a full, brain-wide map of the activity of single neurons during decision-making,\u201d explains co-founder of IBL Alexandre Pouget. \u201cThe scale is unprecedented as we recorded from over half-a-million neurons across mice in 12 labs, covering 279 brain areas, which together represent 95 percent of the mouse brain volume. The decision-making activity, and particularly reward, lit up the brain like a Christmas tree,\u201d adds Pouget, who is also a group leader at the University of Geneva in Switzerland.<\/p>\n Modeling decision-making<\/strong><\/p>\n The brain map was made possible by a major international collaboration of neuroscientists from multiple universities, including MIT. Researchers across 12 labs used state-of-the-art silicon electrodes, called neuropixels probes, for simultaneous neural recordings to measure brain activity while mice were carrying out a decision-making task.<\/p>\n \u201cParticipating in the International Brain Laboratory has added new ways for our group to contribute to science,\u201d says Fiete, who is also a professor of brain and cognitive sciences, an associate investigator at the McGovern Institute for Brain Research, and director of the K. Lisa Yang ICoN Center<\/a> at MIT. \u201cOur lab has helped standardize methods to analyze and generate robust conclusions from data. As computational neuroscientists interested in building models of how the brain works, access to brain-wide recordings is incredible: the traditional approach of recording from one or a few brain areas limited our ability to build and test theories, resulting in fragmented models. Now, we have the delightful but formidable task to make sense of how all parts of the brain coordinate to perform a behavior. Surprisingly, having a full view of the brain leads to simplifications in the models of decision-making,\u201d says Fiete.<\/p>\n The labs collected data from mice performing a decision-making task with sensory, motor, and cognitive components. In the task, a mouse sits in front of a screen and a light appears on the left or right side. If the mouse then responds by moving a small wheel in the correct direction, it receives a reward.<\/p>\n In some trials, the light is so faint that the animal must guess which way to turn the wheel, for which it can use prior knowledge: the light tends to appear more frequently on one side for a number of trials, before the high-frequency side switches. Well-trained mice learn to use this information to help them make correct guesses. These challenging trials therefore allowed the researchers to study how prior expectations influence perception and decision-making.<\/p>\n