Probing the Untethered Brain

Measuring learning and memory on the go

Studying memory using VR

Nanthia Suthana is the Associate Director of the Neuromodulation Division at the Semel Institute for Neuroscience & Human Behavior. She sat down to talk about her research using permanent brain implants to study learning and memory in humans, her uncharted journey into the brain sciences field and why she is so passionate about outreach. Interview by Berly McCoy.

Could you tell me about your research and how it began?

In 2013, the FDA had just approved a new permanently-placed brain implant device that treats patients with epilepsy. It records seizure activity and then uses electrical stimulation to prevent a seizure from spreading, such that the person hopefully doesn’t notice that they were about to have a seizure.

When I saw that, I thought, “Oh my gosh, this device is going to be implanted in thousands of people to record a brain region that I’ve been studying for 10-plus years in freely behaving humans.” The majority of the research on this topic was done in freely behaving rodents and we didn’t know whether the results would translate to humans. I realized this was an opportunity to bridge that gap.

The first basic question my lab is asking is “What is the role of these brain regions in learning and memory in freely moving humans,” and “Is it similar to what we see in maze memory studies in rats and mice?” And when we don’t see similar effects, “What are the variables that are causing these differences?”

To investigate this, we outfit participants who have implanted sensors with motion capture equipment that can track their eye movement, position, speed, heart rate, blood pressure, respiration, skin conductance and pupil size changes. You name it, we can track it. We simulate real world experiences using virtual reality and augmented reality to understand how these activities modulate brain activity in the regions related to learning and memory.

One thing we’ve found is that eye movements modulate these brain activity patterns when someone is completing a task, which makes sense because we’re a visual species. Another thing we’ve found is that these brain regions are modulated differently by the type of task an individual is performing. For example, if someone is walking to a particular visible landmark or location versus trying to remember where they put their keys, those are two very different tasks. One is a very explicit memory question and one is not. When we compared the two types of tasks, we noticed different brain activity patterns.

Another big finding is that these patterns of activity that are modulated by task or by memory are also modulated by someone’s proximity to boundaries such as a wall. When a person is looking for objects in space, boundaries become very relevant for anchoring them in that space. But they’re also modulated by someone else’s position. That was a very important discovery because that’s something that can’t be done in humans with conventional neuroimaging approaches.

This work is the beginning of a very long puzzle in understanding how this brain system tracks our position as we maneuver through space. There are so many things that are modulating these activity patterns and we are taking the first steps toward understanding what this brain system does in freely-moving humans.

Another part of my lab uses the implanted device for stimulation to test potential new treatments. We have a clinical trial involving combat veterans with very severe, intractable post-traumatic stress disorder. We use this device in a similar way to the epilepsy patients, but instead of using electrical stimulation to prevent seizures, we’re using it to suppress the negative symptoms related to problematic, traumatic memories.

How did you get interested in your field?

Halfway through my undergraduate degree I decided to withdraw. I took a year off, but I didn’t plan to come back. I was undeclared and very much so undeclared in the sense that I had no idea what I wanted to do. I was very lost and that’s partly why I dropped out of school and decided to travel.

I backpacked through Europe and stayed in hostels for several months. I pursued my artistic passions and started reading for fun. I specifically remember reading about Henry Molaison, or H.M., a man who had portions of his medial temporal lobe surgically removed to control his epilepsy, which resulted in an inability to form new memories. It was very shocking to me and I just wanted to understand why. I wanted to know how people learn so differently and how they have different memory capabilities.

I hadn’t learned anything about the brain in high school or in college. It just wasn’t taught in the curriculum in those days. I became really fascinated with this whole new field that I had no idea about so I started going to the library and reading about it. That’s when I realized I wanted to learn more and go back to school.

Can you talk about your educational journey?

I re-enrolled at UC Berkeley and then transferred to UCLA because I wanted to pursue a major in neuroscience, which Berkeley didn’t have at the time. I took every neuroscience class that existed at UCLA. I was totally in love with all the classes.

I graduated in 2005 and started a PhD program at UCLA the same year studying learning and memory with Susan Bookheimer and Barbara Knowlton. My dissertation focused on using neuroimaging to understand the same brain structure that H.M. had removed, the hippocampus, and its role in learning and memory, particularly in spatial memory.

In 2009 I finished my PhD and started a postdoc with Itzhak Fried in the Department of Neurosurgery. I continued to focus on the same topic of episodic memory, as well as spatial memory.

Once I finished my postdoc I stayed at UCLA for a one-year position as a lecturer teaching undergraduate courses. I started applying for faculty jobs, received some offers and ultimately accepted one from UCLA.

What do you hope will be the impact of your research?

A lot of the functions we study are tasks that people with Alzheimer’s Disease can’t perform. When we understand how it works, then we can start to think about how we can develop treatments for when things go wrong and ask, “Can we push the system into a more normal state using stimulation?”

We can now test out these new therapies in a realistic, ecologically valid environment that will hopefully better translate to their real world. It has relevance for memory disorders, like Alzheimer’s disease, epilepsy, memory impairments and traumatic brain injuries. We’re ultimately interested in understanding the system such that we can improve the system. For PTSD, we’re interested in doing the opposite, which is suppressing problematic memories that can’t be forgotten.

I hope that these studies will contribute to our knowledge of how these brain areas work and ultimately lead to our ability to develop better treatments for when things are not working appropriately.

On the technology side, the platform that we’ve created is really the first of its kind. We’re hoping that it will enable other people to do similar studies.

What activities are you involved in outside of your research?

I direct a training program in translational neurotechnology, which is focused on developing new technologies that can treat neurological and psychiatric disorders. We have trainees in neuroscience, bioengineering, electrical engineering and physics. It’s a very interdisciplinary program aimed at educating folks to take new technologies from bench to bedside.

I’ve done outreach for as long as I can remember. I’m the director of neuroscience outreach for the brain research Institute. We organize Brain Awareness Week and the Brain Bee, which is a neuroscience competition for high school students. I spent two days a week for a year in a high school teaching neuroscience to students through an NSF program. I helped develop a course at UCLA called Project Brainstorm to teach undergrads how to communicate neuroscience to K-12 students, which happens every winter and spring.

Outreach is a passion of mine because I never learned about the brain before I was 19 years old. I felt like that was a problem. So a lot of my outreach is to help educate this younger community earlier about the brain and how it works and get them excited about science. I was not excited about science before I left school and that’s also a problem in terms of how we educate the sciences. The other reason I focus on outreach is of course under-representation in the neuroscience community and STEM more broadly.

What else would you like to share about your identity?

I come from a mixed, underrepresented background. I’m multicultural. I think a lot of that contributes to my identity and who I hope the community will better represent. I think that folks like myself have not been well-represented, especially in the engineering side. I’ve often been the only woman in the room, so to speak, and that needs to change. It’s led to a lot of imposter syndrome and inhibited anger that it is that way. I have a lot of frustration in terms of comments and treatment that comes with being an underrepresented person. That frustration contributes to me hoping to change that room and make it more balanced so that future young women or minorities don’t have to experience these kinds of uncomfortable feelings that ultimately make it harder for them to progress and to do good work, and is sometimes a source of more stress than the first job.

It’s unfortunate because you don’t want to take away from the first (research) because of the second (outreach), but you also realize that no one else is going to do it if you don’t. So it’s a very interesting, constant struggle and a balance to maintain, because they are both important. But it is very challenging.

Read more about Dr. Suthana’s work: Wireless Programmable Recording and Stimulation of Deep Brain Activity in Freely Moving Humans or visit her website.