Download this episode
What is “memory clutter”? Can we make it go away? Audrey Duarte, an associate professor in the School of Psychology, uses magnetic resonance imaging and special tests in her Memory and Aging Lab to discover what causes obstacles in the brain’s pathways as people age.[upbeat music]
- Renay San Miguel
-
Hello and welcome to ScienceMatters, the podcast of the Georgia Tech College of Sciences. I’m Renay San Miguel.
Even though I’m not a Georgia Tech student, I wanted to experience the kind of research they do.
But not in a regular laboratory. I had my sights on the Georgia Tech Center for Advanced Brain Imaging, or CABI, located on Marietta Street, near West Campus.
What do they research here? Our ability to create memories.
- Brittany Corbett/Graduate student
-
You’re going to see an object four times, and they could be paired with a different face or object each time.
- Renay San Miguel
-
That’s second-year Ph.D. student Brittany Corbett taking me through procedures. She’s asking me to, quote, “encode” these pictures in my memory, and then she’ll ask me to remember them later.
As they ask questions, Brittany and CABI technicians gather data on brain waves elicited by my responses. For researchers studying the brain, CABI has two important tools: an electroencephalogram, or EEG, machine, and a magnetic resonance imaging or MRI machine.
MRI scans – called functional MRIs – or fMRIs -- because they measure blood flow -- can give researchers a closer look at the parts of the brain involved in processing memory. The EEG is designed to gather data in real time – in the millisecond range.
- Renay San Miguel
-
So now they’re getting ready to fit me with an EEG skullcap of some kind -- I guess that’s the technical term that we’re going to be using -- but that’s going to be used in the normal experiments to monitor brain waves.
Watching from a few feet away is Audrey Duarte, associate professor in the School of Psychology and the principal investigator of the Memory and Aging Lab.
Because memory is key to who we are and how we react to situations, Duarte and her fellow researchers are trying to figure out how memory fails as we get older. A failing memory can be a sign of serious disease such as Alzheimer’s, but it can also impact otherwise healthy, aging adults.
What exactly causes those memory failures? Can they be prevented by cognitive activities, just as physical exercise helps maintain muscular and cardiovascular fitness? Could this research be applied to new ways of educating students, particularly those on the autism scale?
Those are the questions Duarte is trying to answer.
- Audrey Duarte
-
The facial movements, the tics, may not be a part of the response.
- Renay San Miguel
-
Right now, the only questions I want Duarte to answer are: What kind of brain waves interest her, and why won’t my facial expressions be part of the response?
- Audrey Duarte
-
The signals, though, that we’re interested in coming from your brain are so much smaller by the time they reach the scalp, because they have to travel through brain, through cerebral spinal fluid, through the skull, through the fat, and through the hair.
- Renay San Miguel
-
Oh wow.
- Audrey Duarte
-
And then the skin, so by the time they get to the surface they’re teeny, relative to the electrical activity produced by the muscles on your face, or your jaw muscles, so we monitor those, and we can pretty easily filter that noise, that muscle activity out of the signal. In addition we amplify these electrical signals coming from your brain.
- Renay San Miguel
-
The types of brain waves – alpha, beta, delta, gamma, and theta – do correspond to different kinds – or frequencies -- of brain activity. Delta waves, for example, are tied to deep states of sleep, while beta waves dominate when we are awake and thinking at work or school. Duarte and her team study the strength of those waves as you’re engaging in a memory task. They’ve found that wave strength is related to whether someone will successfully remember something later in the process.
- Audrey Duarte
-
For an example, we can measure in real time how long it is taking -- how much neural evidence for a scene does your brain need to manifest, in order for you to say I saw a scene, or I saw a face.
- Renay San Miguel
-
And as I get older, that time might lengthen?
- Audrey Duarte
-
That’s one of the questions we’re trying to answer.
(Upbeat music)
- Renay San Miguel
-
Let’s leave the Center for Advanced Brain Imaging for a few minutes. Let’s dine at an imaginary restaurant that we’ll call Fouillis de Mémoire.
(Sounds of busy restaurant)
- Renay San Miguel
-
It’s a busy place, as you can hear. Let’s say you and a friend are having dinner. Your friend just shared a serious office dilemma, and wants your opinion. But the table next to yours is awfully loud.
(Busy restaurant sounds)
- Renay San Miguel
-
Music is blasting, a car alarm blares from the street, and other loud noises distract you.
(Sound of dropped dishes)
- Renay San Miguel
-
As you’re leaving, your friend again asks your opinion about the office dilemma. But you can’t remember because of all the restaurant distractions going on just as your brain was trying to process new information. Duarte refers to such distractions as memory clutter. It’s a problem, and she is trying to find out why older brains are more susceptible to memory clutter than younger ones. Does our digital, too-much-information age, with smartphones joining us at dinner, play a part in this? Or is it simply aging brains that can’t keep up?
- Audrey Duarte
-
Oh yeah, this happens to me more and more every day as well. (Laughter)
- Renay San Miguel
-
I think me too! It’s just, you know, and there’s all these data now; there’s more data that we’re dealing with than ever before, a lot of distractions.
- Audrey Duarte
-
And it is absolutely true: There is, objectively, more noise out there in the world, just, you know, stimuli everywhere. And we know, that as we age, it becomes more challenging both. We can measure this in the lab but also, subjectively, it’s more challenging for people to filter out irrelevant information. You don’t always know what’s relevant, what isn’t, but, you know, if we’re having a conversation and something appears in my peripheral vision outside my window, I – part of me wants to orient to that information, and that is going to detract my attention from this conversation, and then I will probably have difficulty remember what we were talking about. And so this ability to filter out what’s distracting is something that does seem to decline as we age.
(Sounds from busy restaurant)
- Renay San Miguel
-
By the way, the name of this fictional restaurant, Fouillis de Mémoire? That’s French for memory clutter.
(Upbeat music)
- Renay San Miguel
-
Back in Duarte’s office on campus, the subject turns from memory clutter, to memory loss and impairment.
That can happen with normal aging, and it can be the result of neurodegenerative diseases like Alzheimer’s. Many might worry that memory changes they are experiencing are the onset of Alzheimer’s.
- Audrey Duarte
-
The issue is that it’s very difficult to know early what’s a sign of, later this person’s going to develop dementia and this person isn’t. We don’t have a good answer for that at the moment. So it’s just based on their performance on memory tests that we might give in the laboratory. It’s very difficult to tell in an early stage.
However, you really can see differences emerge as people develop more pathology in the brain. And they’re starting to have more severe memory impairment. And really what’s noticeable is, beyond memory impairments, seen changes in their ability to function on a daily basis – so, you know, remembering to turn off the stove, that sort of – you know, remembering you went to the grocery store and forgetting why you’re there – that sort of thing. And so then it’s quite clear, but then it’s quite advanced as well.
- Renay San Miguel
-
Alzheimer’s is an attack on a person’s memories. Certain head injuries and other medical conditions can have the same effect on memory. So I wanted to know: Do scientists know if memory is located in a specific section of the brain? Duarte’s research has focused on the prefrontal cortex, but she says it’s hard to pinpoint exact locations where memory sits within the brain.
- Audrey Duarte
-
I’ll just first be clear about what we mean by “memory” because it’s definitely not one thing. So everybody sort of, I think, understands these terms: “short-term memory,” “long-term memory.” And, you know, when you think of what a short-term memory is, what we as researchers believe that to be is something that we can remember over a period of seconds to a minute. So you ask someone for their phone number, you have to retain that in your memory for a short time before you can write it down or put it in your phone, you know?
And so that kind of memory has – that kind of memory could become a long-term memory, actually. But long-term memories, which is really what I study in my laboratory, what we work on, these are memories that can last a lifetime. So remembering the days of the week, the presidents, you know, of the United States, remembering what you had for dinner last night, or what you did five years ago on your birthday – these are all long-term memories.
And in terms of what parts of the brain or what networks of the brain are important for making these memories, it’s really not just one part of the brain; it’s really many parts. The prefrontal cortex that you mentioned is absolutely essential in helping to form memories and helping to recover them, but memories don’t sit there. It’s also true that a region called the hippocampus, we know is very important for memory.
So these regions of the brain, many of them are important for processing the information that you’re experiencing. That information is processed by various parts of the brain: visual areas, olfactory areas, auditory, are bound together – this is how we think this is happening – bound together by regions of the brain like the prefrontal cortex and the hippocampus that communicate with one another. Then what happens after that is still a mystery. But what we believe happens is what we say is that these memories become consolidated, and they become distributed across the brain. So you can’t look in the brain anywhere and say, ‘you like this movie?’ Do you remember the movie, Eternal Sunshine of the Spotless Mind?
- Renay San Miguel
-
…of the Spotless Mind? Yes, yes yes.
The 2004 movie starring Jim Carrey and Kate Winslet won the Oscar for best original screenplay, thanks to an original premise: In the movie, people can have painful, traumatic memories erased from their minds.
Duarte brings up the movie to illustrate that unlike its premise, memories are generated from all over the brain, not just in one place. This becomes apparent when you consider that as Alzheimer’s progresses in patients, one of its most tragic aspects is that they can fail to recognize their loved ones.
- Audrey Duarte
-
It takes a lot of brain damage for that to happen. And that makes sense if you think about where the memories are: they’re everywhere.
- Renay San Miguel
-
Another area of Duarte’s research? The brain activity that’s going on as you’re learning something new plays a role in memory. That’s where the equipment and resources at the Center for Advanced Brain Imaging come in handy for Duarte’s researchers, as they try to tie certain brain waves to memory recall.
- Audrey Duarte
-
Looking at activity just before people look at – try to remember anything or try to learn anything – and that activity – and we can measure it with EEG, we can measure it with fMRI, looking at areas of the brain or patterns in real-time – that activity is predictive of later memory as well. What is still a question that people are trying to understand is what that activity is. So is it just whether you’re attending in the right place to be able to encode something to memory? Is it just how motivated you are? Is it a reflection of motivation? Is it a reflection of the brain areas that are really important for memory are sort of turned on for whatever reason?
- Renay San Miguel
-
Duarte’s office within the Center for Advanced Brain Imagine may be called the Memory and Aging Lab, but the work there also has potential applications for younger people, and how they are taught in classrooms.
- Audrey Duarte
-
In the classroom you can imagine you have an EEG cap on someone’s head, and this is just measuring activity as people are paying attention or whatever they’re doing in the classroom. And this has not been implemented yet, I will say, but we could potentially get there in the next five years or so, where we can measure the activity and say, “this person is in a good, what we call ‘brain state.’” Right now is the time where they should be presented information that they should learn.
(Upbeat music)
- Renay San Miguel
-
Students with ADHD or on the autism spectrum often get individualized education plans, or IEPs, from their school districts. Duarte says she is very interested in whether her research could result in personalized instruction plans for students based on how they retain information.
But that’s still years away from reality, and on the lower end of the age and memory scale. Those of us on the upper end, in our late 50s, will keep a close eye on Duarte’s work in her Memory and Aging Lab.
My thanks to School of Psychology Associate Professor Audrey Duarte, 2nd year Ph.D. student Brittany Corbett, and the other researchers in the Memory and Aging Lab. And our thanks to the Center for Advanced Brain Imaging, which is used by both Georgia Tech and Georgia State researchers.
Siyan Zhou, formerly a research associate in the School of Psychology, composed our theme music.
I’m Renay San Miguel, and you’ve been listening to ScienceMatters, the podcast of the Georgia Tech College of Sciences.
[upbeat music]
