To answer these questions, the researchers zoomed in closer. When the researchers tested the animals’ memory of this new skill weeks later, they found that those mice that still remembered the skill showed increased activity in the same neurons that were first identified during the learning period, showing that these neurons were responsible for encoding the skill: the researchers had observed the formation of memory engrams.īut how do these particular groups of neurons take on responsibility for learning a new task in the first place? And how do they actually improve the animal’s performance? The researchers tagged these potential engram cells with a fluorescent marker so they could see if they also played a role in recalling the memory later on. Using genetic wizardry developed by the lab of Liqun Luo, a Wu Tsai Neurosciences Institute colleague in the Department of Biology, the researchers were able to identify specific neurons in the brain’s motor cortex - an area responsible for controlling movements - that were activated during the learning process. In their new study, published Jin Neuron, the researchers trained mice to use their paws to reach food pellets through a small slot. “These refined neuron pathways were thought to be the basis of a memory engram, but we wanted to know exactly how these pathways emerge.” “When you’re first learning to shoot a basketball, you use a very diverse set of neurons each time you throw, but as you get better, you use a more refined set that’s the same every time,” said Roth. However, whether memory engram neurons exist for motor skill learning remains unknown.ĭing and postdoctoral scholars Richard Roth and Fuu-Jiun Hwang wanted to know how these engram-like groups of cells get involved in learning and remembering a new motor skill. Previous studies have shown that some forms of learning activate specific neurons, which reactivate when the learned memory is recalled. The concept of such a memory trace - sometimes called a memory engram - has been around for more than a century, but identifying exactly what an engram is and how it is encoded has proven extremely challenging. Memories are thought to be encoded in the brain in the pattern of activity in networks of hundreds or thousands of neurons, sometimes distributed across distant brain regions. Clearly, there’s a huge difference in the way that motor memories are formed.” “Some studies on Alzheimer’s disease included participants who were previously musicians and couldn’t remember their own families, but they could still play beautiful music. “We think motor memory is unique,” said Jun Ding, an associate professor of neurosurgery and of neurology. It may even help illuminate the root causes of movement disorders like Parkinson’s disease. Now, a new study by scientists with the Wu Tsai Neurosciences Institute is revealing exactly how motor memories are formed and why they are so persistent. This may be because physical skills - dubbed motor memories by neuroscientists - are encoded differently in our brains than our memories for names or facts. Why is it that someone who hasn’t ridden a bicycle in decades can likely jump on and ride away without a wobble, but could probably not recall more than a name or two from their 3rd grade class?
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