Nanthia Suthana, PhD, Neuroscientist and assistant professor at the David Geffen School of Medicine, UCLA, department of psychiatry and biobehavioral sciences, neurosurgery, and bioengineering, talks about a new way to explore the functions of the human mind.
Could you explain what you and your colleagues are looking at in the lab right now?
SUTHANA: We’re looking at how the brain keeps track of a person’s location as well as how it keeps track of other people’s location in a shared environment with others.
Can you walk us through the steps of how you’re measuring this?
SUTHANA: Traditional methods of measuring brain activity don’t allow a person to really move around. To do this experiment, we had to develop a technique that allows us to record brain activity wirelessly while an individual is free to maneuver through space. We combine this platform with eye tracking measurements so that we can see where they’re looking. When there’s someone else in their environment, we can track where they’re looking, their gaze, position and eye movements. So, we use these techniques in individuals who have already implanted brain electrodes for treatment of seizures to try to predict seizure activity and stimulate to prevent them from occurring. Now, there are a couple of thousands of these patients in the U.S. and a couple of hundred in our local area. We’re able to bring in those who are doing quite well and haven’t had a lot of seizure activity because the device is presumably working successfully and record their brain activity from this device. As they walk around a room, they learn locations in the room and alternate with watching another person walk around the room and keep track of their position relative to locations they’d already learned. So, it’s a spatial memory task. We’re able to look at the activity deep in the brain in an area that we know is first affected in Alzheimer’s disease. We’re very interested in how this area works such that we can inform potential future therapies for treatments of Alzheimer’s and other disorders that cause memory impairments.
What does the data suggest at this point from what you’re seeing with these people?
SUTHANA: The most dominant finding that we found was a signal called a theta oscillation. It’s a brain wave that occurs about eight times per second that strengthens when you are closer to an environmental boundary, like a wall. What’s interesting about this signal is that it does the same thing when you’re tracking someone else’s position. So, in other words if you’re sitting in a corner and watching someone else as they approach a wall, that signal begins to dominate. You can essentially use this signal to extrapolate where the person is relative to the walls of the environment or the center of the room.
What are the benefits that our brain is able to discern those boundaries?
SUTHANA: For one, this is the first time any scientist has been able to record from these signals as someone is moving around and while observing another person do the same. So, it’s important in that it showcases this platform and opens up a new area of human neuroscience investigation. Second, it’s important because we there is so much we don’t know about this brain area in humans and how it encodes or forms memories for physical space or even for events in your life in the real world. For instance, memories for what you had for dinner last night or an important event such as a wedding or a birthday and why in some patients, like in Alzheimer’s disease, these memories breakdown. We really need to understand how this brain area supports these critical functions, like forming memories for everyday events or forming mental maps of an environment, and to develop therapies that will work for these patients. This is the beginning to a new area of human neuroscience in naturalistic settings since much of what we know thus far on these topics has been from animal studies.
So, how does this work in sports? I mean, you’ve got all those people running in different directions, how does it work so that they’re not constantly running into each other?
SUTHANA: That’s really the next experiment. When we have multiple people in the room, how are these signals changing, and do they shift with our focus of attention on each person? That’s what we think is going on. It will be an interesting experiment to try next.
You mentioned bringing in people who have the electrodes already implanted because of seizures. Was there another group of people you included in this research?
SUTHANA: We published a separate paper that included all the details for replicating the backpack. This current study we’re talking about used that backpack technology to acquire the data. So, it’s a follow-up experiment in terms of using the technology for a scientific question that we were interested in. But, yes, the original methods paper includes all the details on how to replicate this backpack such that other researchers can use it for their studies in other types of patients even those without epilepsy.
What is the section of the brain we are talking about?
SUTHANA: We’re talking about the medial temporal lobe which consists of several regions including the hippocampus and entorhinal cortex. These are two very important areas for memory and spatial navigation, and are areas that are first affected in Alzheimer’s disease.
Is there anything else that would be important for viewers to know?
SUTHANA: I would like to highlight that we are also excited about this study because of all the possible studies that can along come after it. So, yes, we’ve discovered a new important piece of the puzzle, but even more exciting is the door that’s open to further discoveries and not just from ourselves but other groups that we hope will adopt this technology and start to ask really interesting questions beyond navigating space with one person. I’d also like to note that there is a nice summary article written by Hugo Spiers in Nature News and Reviews on our recent study for those interested in a shorter overview of the findings. There is an illustration from that paper that I thought was quite effective in showing the study design. Another interesting result we found was these theta signals that track position for oneself and for others was highly dependent on what the individuals were doing in the task. So, whether when they were searching for a hidden location, this signal was present. When they were not searching for a hidden location and simply walking to a cue on the wall, the effect was not present. What that tells us is that the boundary-modulated theta signal may be dependent on whether one is engaged in tracking their own or someone else’s position. For example, when you’re walking down the street you could be thinking about a million other things. You can be thinking about what you’re going to do when you get home; you’re not always paying attention to your location. You might all of a sudden take notice of your position if needed, but otherwise you can zone out for the most part. These brain representations of our space seem may thus only be present when we’re actually paying attention to our location or someone else’s and not when we’re daydreaming about something else. This finding is very interesting to us, because this is something specifically in humans that we can explore in a study, whereas in animals, this question may be more difficult to answer. This of course is interesting to us for insight into the human experience, and really understand how our cognitive shifts, or mental shifts, can modulate or affect these brain signals. So this is likely what we’re going to focus on in our future studies, how attention and memory modulate these signals that can track our location and other people’s location.
Fascinating! When do you get back into the lab?
SUTHANA: We’re still doing research, just using a socially distanced protocol where one person is there at a time. We are also not recruiting anyone older than 65. Most of our patients are in their 30’s or 40’s. UCLA is also vaccinating all the health care staff and professionals. So, nearly our entire team has received their shots and so we are slowly getting back to normal. But we did spend the last year writing a lot and analyzing data. So perhaps that is why we had more papers come out in these last few months.
Interview conducted by Ivanhoe Broadcast News.
END OF INTERVIEW
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