Cognitive neuroscientist Rosie Cowell at the University of Massachusetts Amherst recently received a five-year, $599,619 CAREER award from the National Science Foundation to develop and test a theory of how memory interacts with fine-grained visual perception and how both brain functions depend on the medial temporal lobe (MTL), which once was thought to be critical for memory but not for visual perception.
In the past decade, she explains, it has become clear that a segregated model of separate brain regions being responsible for single functions such as language or memory is not accurate.
"It's been called the Swiss army knife theory," Cowell says, "where each tool in the brain does only one thing. But that view of the brain is unraveling. Now it's understood that the whole brain is involved in many functions, and brain activation occurs in patterns across neural networks. This seems to be closer to what's actually going on."
She will use computational modeling plus memory experiments with human volunteers, some with and some without memory loss, to make predictions about brain activation patterns, and test them. She explains, "We can use a computer to help us think about how the brain might work by using it to make predictions for both brain patterns and behavior, and testing those predictions. This should allow us to understand how brain activity is linked to behavior, in particular in the MTL, at a level not seen before."
Memory is critical to daily life, letting us recognize our friends' faces and recall where we parked, but it is fragile and declines with age. In people with MTL damage, certain specific kinds of memory, such as discerning subtle differences between similar objects, can deteriorate dramatically. Older theories said that the MTL is dedicated solely to memory, but now it's clear that the MTL is important to other cognitive tasks such as imagining the future, or visually discriminating between two very similar objects, which is part of high-level visual perception, Cowell says.
People with MTL damage have trouble with details that help to distinguish similar things, for example, the difference between identical twins. For that task, she notes, "you need a holistic representation, so the brain can put together all of the features that make up each whole face, including the few tiny differences. This brain region ties together a bunch of separate features into a unique combination. When you call up that combination of features in your mind's eye later, it corresponds to a very specific, very accurate memory."
By applying and testing her theory both to amnesia caused by brain damage and more moderate memory loss caused by normal aging, Cowell's project will investigate whether these two forms of memory loss can be explained by the same mechanisms.
The neuroscientist will use the campus's new MRI scanner to compare her computational models of the brain with what happens in real people. "The model looks a bit like the brain and it makes predictions about behavior, but these always need to be tested. We will measure activations in the brains of people as they perform memory and cognitive tasks inside the scanner and see if those data fit with the predictions, to test whether the model is in line with both neurobiology and behavior."
She adds, "If we're successful, it might reveal what amnesia does to the brain, and what neural activation patterns look like when you have amnesia and when you don't. Damage in this region is intriguing; I hope to provide a unified theory of why the MTL is so important for memory and certain other functions, and to explain what those things have in common that makes the MTL so critical for an array of different functions."
Her broader career goal, Cowell says, is to show that separating the study of emotion, memory, perception, attention and other brain functions is not the best way to understand the brain. "If you look at a psychology textbook today, these are all in separate chapters, which made sense when scientists started out by studying cognition according to the various mental functions that humans possess."
"But now that we know more, the evidence doesn't support that segregated model, in terms of the brain. Now it makes more sense to build theories of brain function by starting instead with the biology of the brain, how it is organized, its architecture, and its patterns of activation, and working up to figure out how it contributes to mental functions."
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