The Amazing, Changing, Aging Brain

The Amazing, Changing, Aging Brain

#3 in my series for International Brain Awareness Week.  In addition to needing to do a #brain post, I also needed to finalize my text for the 3 Minute Thesis I’m supposed to tape tomorrow in advance of our University’s competition – so this post doubles for both. And having done this now – trying to summarize years of scientific research for a lay audience in a 3 minute presentation – I think that every graduate dean whose university is hosting a 3MT should have to do one himself or herself. The students make it look so easy, but it really is incredibly hard!! You can check out some of the winning 3MTs from this U Queensland site (where it all started): http://goo.gl/8rcMd 

Canada is graying before our very eyes. The fastest-growing segment of the population is now the 65+ crowd. This means that the traditional population pyramid is being turned into a population T, so that we soon will have many more seniors than children.  

This shift in demographics will impact every aspect of our lives: from healthcare to the workforce, from transportation to communication. And understanding how the brain changes with age is critical for every one of these areas. 

But we still have a lot to learn about the aging brain. Until recently it was believed that we each effectively had a best-before-date – that as we aged the brain could only deteriorate.  

The work in my lab challenges that notion, asking whether, when, and how the older brain can maintain – or even improve – function.

In one experiment, we asked younger and older subjects to discriminate two sets of gratings with slightly different spatial frequencies – basically discriminating fatter and thinner bars. Younger and older people performed well on this task and, indeed, performance was indistinguishable across the two groups. But we also measured brain activation while our participants were doing the task. And that’s where things got interesting.

When we looked at how patterns of activation across the entire brain correlated with behavioral performance, we found that in younger brains, the occipital cortex, which is primarily responsible for vision, played the key role, as one might expect given that this was visual discrimination task. 

But in older brains, the hippocampus and prefrontal cortex played the key roles, areas that in younger people  normally are associated with memory and attention. It was as though the older brains had effectively rewired themselves – using their memory and attention systems to do vision. 

If that were the case, you might expect that older people would have more difficulty on memory and attention tasks. And, in fact, that’s precisely what we and others have found. 

For example, in another experiment, we asked people between the ages of 15 and 85 to do different kinds of attention tasks. In the focused attention tasks people simply had to say what letter appeared or where a spot appeared on the screen.  In the divided attention task, people had to do both of those things at the same time.  

We found that decade by decade by decade people got worse and worse on the divided attention task, and this is important to know because these sorts of tasks are correlated with performance on real world activities, like driving.

Does that mean we should take the keys away from people once they turn 80, 70, 60? Or, can older people (and their brains)  learn to adapt to these more complex situations?  

To answer that question, we asked people to perform these attention tasks over the course of a couple of weeks, measuring how  performance changed with practice. By the end of training, both older and younger people were able to do the two tasks just as well as they could do the one – we could teach older people to multitask. 

So clearly, our old notions of old brains are quite out of date. There should be no best-before-date for people: Our brains are incredibly flexible, and we certainly can teach older brains new tricks.

#ScienceEveryday (when it’s not #ScienceSunday ) #brain  

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