The York University Magazine

YorkU Spring 2014

The alumni magazine of York University

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14 YorkU Spr ing 2014 The Plastic Brain New research sheds light on how our brains can relearn lost tasks You might think your brain is hardwired from infancy, and that it remains pretty much unchanged throughout life, but new research at both York and abroad shows that's far from the case. In York psychology Professor Kari Hoffman's Perception & Plasticity (P&P) Lab, she and research colleagues are discovering our brains' neurons are always changing and having new "conversations" with each other. Think of it as a giant cocktail party where new groups of people are constantly meeting, coming and going, and, in doing so, generating small cliques where fresh conversations are always springing up (even when we're asleep) and information sharing is ongoing. It's like a 24-7 meet-up. Hoffman says many of the brain's mysterious functions and dysfunctions lie in its ability to adapt and learn. Yet, she says, we know very little about how this learning happens in intact, living brains when all the parts are humming away in concord or – in the case of diseases such as Alzheimer's or in brain- damaged individuals – discord. "We know now that injured brains can regenerate them- selves and find new paths or different ways to do things," says Hoffman. "That makes sense, because our brains are always looking for ways to maximize the results of incoming stimuli to process it better and faster. That means the output – move- ment, speech or whatever – will be more efficient." The P&P Lab focuses on three essential areas: memory, perception and neural interactions. Hoffman's research looks at how we perceive and process social signals – such as faces, voices, body parts and gestures – how we form our memories of them and even the role sleep plays in the way neurons talk to each other when the mind is at rest. Researchers have found that nighttime seems to be when memories of what we observed during the day are consolidated. "The name of the game in our brain is about dynamics," says Hoffman. "We clearly are not hardwired from birth and there are differences in how our neural networks talk to each other as we develop. We live in a world of objects, but what actually hits our eyes are wave- lengths of light. But that's not how we describe our surround- ings. So how does the brain learn to differentiate subtle differences in, say, faces or dif- ferent kinds of boxes – perhaps a wood one versus a cardboard one? Smaller or bigger? It's incredibly complex. And even the best computer software has big difficulties doing what our brains do effortlessly." Hoffman says her research is all about trying to figure out how our brains do this so effortlessly. What she's found is our brains' neural networks seem to talk to each other. "We think these cliques allow us to process information faster and more efficiently and that helps reduce the background noise that you might have if you had millions of neurons all responding individually," says Hoffman. "It's a bit like a piece of music. If the right parts of the brain are sent the right infor- mation at the right times, the rhythm of the music flows. But if the wrong signals are sent for processing, the flow of the music is disrupted. That's what we mean by the brain's plasticity. We think that timing-based plasticity – the way neurons change the tune as it were – is by their timing with each other." Essentially, Hoffman listens to the conversations people's brains are having via their neural networks using magnetic resonance imaging. She looks at these networks both when they're being stimulated (in experiments) and afterwards when the brain is at rest but still busy processing and sorting what it's seen hours earlier. Hoffman likens the challenges in her work to listening in on the conversations among a whole football stadium of people: "Imagine you care about each individual in that stadium and what he or she is saying among people close to them or further away. And then what fans of the other team are saying and, finally, what various cliques of fans on both sides are saying." Ultimately, Hoffman's work could have far-ranging implica- tions for people with Alzheimer's disease, she says. "If we can find the right stimulation parameters for the brain's 'good' smooth rhythms, that could have a big impact on helping improve Alzheimer's patients' memories in the future." Kari Hoffman: Exploring how old brains learn new tricks YorkU_Summer2014 _YorkU_Oct10_FINAL 14-05-09 12:57 PM Page 14

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