The brain’s code seems to be in constant flux. Neuroscientists are baffled

It is a dogma in neuroscience that certain brain cells respond in the same way to the same thing. Specific neurons always fire, for example, when we see particular shapes and colours; other neurons activate to swing an arm or wiggle a nose. The brain needs this stability, the theory goes, to respond to the outside world in a consistent way. So, when neuroscientist Laura Driscoll began her doctoral research at Harvard University in Cambridge, Massachusetts in 2012, her first task was to establish this baseline by tracking the activity of individual mouse neurons over time. Brains of ‘super agers’ are strong producers of new neurons To Driscoll’s surprise, the baseline kept moving. Over the course of several days, many of the cells’ responses had shifted noticeably. Neurons that had fired when a mouse was in a specific location on day one were barely responding in the same spot after a few weeks. “It absolutely defied all of our expectations,” recalls Driscoll, who is now at the Allen Institute in Seattle, Washington. “This was so surprising that my whole project changed.” In 2017, she and her colleagues reported findings from that project that flew in the face of neuroscience dogma. Over a single day, neurons in the parietal cortex, a hub for processing sensory information, fired predictably in response to specific things, such as the position of the mouse in a virtual maze. …