“A daily commute to work, for example, requires the activity of millions of neurons, but you would be hard pressed to remember what was happening halfway through your commute last Tuesday,” Sheffield said. Sheffield, a postdoctoral fellow in Dombeck’s lab and first author of the study. “We experience events all the time, which must be represented in the brain by the activity of neurons, but not all these events can be recalled later,” said Mark E. The Northwestern study provides evidence against this classic view of neuronal function. Scientists have long believed that the neuronal tasks of computing and storing information are connected - when neurons compute information, they are also storing it, and vice versa. Signals produced in the dendrites (used to store information) and signals within the neuron cell body (used to compute and transmit information) can be either highly synchronized or desynchronized depending on how well the neurons remember different features of the maze. They saw that dendrites are not always activated when the cell body is activated in a neuron. In their study, Dombeck and Sheffield found dendrite signals that could explain how an animal can experience something without storing the experience as a memory. Neuroscientist John O’Keefe discovered place cells in 1971 (and received this year’s Nobel Prize in physiology and medicine), but it is only in the last few years that scientists, such as Dombeck and Sheffield, have been able to image these neurons that represent a map of where we are in our environment. The Northwestern study was published Oct. Understanding how place cells and their dendrites store these types of memories could help us find new ways to treat the disease. Disruption to the brain’s GPS system is one of the first symptoms of AD, with many patients unable to find their way home. Their findings contribute to our understanding of how the brain represents the world around it and also point to dendrites as a new potential target for therapeutics to combat memory deficits and debilitating diseases, such as Alzheimer’s disease (AD). Dombeck and Sheffield are the first to image the activity of individual dendrites in place cells. In the brain’s hippocampus, there are hundreds of thousands of place cells - neurons essential to the brain’s GPS system. Our findings could explain why some experiences are remembered and others are forgotten.” “Now we have uncovered signals in dendrites that we think are very important for learning and memory. “There are a lot of theories on memory but very little data as to how individual neurons actually store information in a behaving animal,” said Dombeck, assistant professor of neurobiology in the Weinberg College of Arts and Sciences and the study’s senior author. This suggests that the cell body seems to represent ongoing experience, while dendrites, the treelike branches of a neuron, help to store that experience as a memory. They observed that when cell bodies were activated but the dendrites were not activated during an animal’s experience, a lasting memory of that experience was not formed by the neurons. The scientists found that, contrary to current thought, the activity of a neuron’s cell body and its dendrites can be different. Sheffield peered into the brain of a living animal and saw exactly what was happening in individual neurons called place cells as the animal navigated a virtual reality maze. Using a high-resolution, one-of-a-kind microscope, Daniel A. It turns out, if you want to remember something about your environment, you better involve your dendrites. Why do we remember some things and not others? In a unique imaging study, two Northwestern University researchers have discovered how neurons in the brain might allow some experiences to be remembered while others are forgotten.
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