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The two awardees received the junior awards and are invited to speak about their research during the Congress. We have the great pleasure to have with us one of the awardees of this year, Dr. Bahne Bahners, who is currently a research fellow at the Brigham and Women's Hospital and Harvard Medical School in Boston.
Bahne, thank you very much for joining and congratulations.
[00:00:47] Dr. Bahne Bahners: Thank you so much. And thank you for giving me the opportunity to join on the podcast.
[00:00:52] Dr. Michele Matarazzo: Yeah, so this is called the Junior Award because it's for younger people. Can I ask you how old are you and a little bit [00:01:00] of your background? Where are you from? What has your career been so far? And also how did you end up working in the field of Parkinson's disease? Was it something you always wanted or it just happened?
[00:01:13] Dr. Bahne Bahners: So I'm 30 years old right now, and I've started medical school, I think now something like 10 years back. And before starting medical school, I've been in a In a caregiver internship, and I've been on a neurological ward and I've seen many patients with movement disorders there.
And it somehow fascinated me how you could By just looking at the patient and how their movements were, could already infer which kind of diagnosis you give that patient and what might be wrong in the brain. So that, that already fascinated me early on, like before starting medical school, even, so I had an interest in urology and then that developed into.
And interest in movement disorders, particularly in my M. D. thesis [00:02:00] in Dusseldorf at the University Hospital. I've worked in the M. E. G. lab with Markus Butz and Alfons Schnitzler on Parkinson's disease and deep brain stimulation, and that's when I started to also develop an interest in electrophysiology and deep brain stimulation.
And then after a two year postdoc after med school with Esther Florin and Alfons Schnitzler, And in the MAG lab, I've started residency in neurology and I've been working a lot in the DBS outpatient department. I was lucky to also see many different patients with movement disorders there.
[00:02:36] Dr. Michele Matarazzo: And how did you end up in Boston?
[00:02:39] Dr. Bahne Bahners: So after my postdoc, I applied for a Parkinson's fellowship, which is awarded by the German Temon foundation, which is a foundation founded by a person with Parkinson's disease who was a radiologist in Germany. And he founded this foundation to fund young people that are interested in Parkinson's disease research.
And [00:03:00] I got this award and was lucky to to join Andreas Horn's lab in Boston was obviously a rockstar in DBS research.
[00:03:10] Dr. Michele Matarazzo: So now going from that award to this current award, I am actually not sure. How many abstracts are sent to the meeting each year. But being one of the top abstract is definitely a great recognition of your work. So you definitely must be proud. Have you attended this MDS Congress before and sent abstracts before, or is this your first time?
[00:03:32] Dr. Bahne Bahners: It's actually my first time. And that was unfortunately due to COVID I, I wanted to go to MDS before, but it was exactly when COVID happened. So I didn't but yeah, I'm excited that my first Congress, I, I'm able to to
[00:03:47] Dr. Michele Matarazzo: I mean, I'm telling you, it's unlikely that you're going to you're going to receive an award every Congress. So it's not, the first one is going to be like this, but probably the other ones are not going to be you know, I hope so, but you never know.
[00:03:58] Dr. Bahne Bahners: It's fine.
[00:03:59] Dr. Michele Matarazzo: Now [00:04:00] the title of the abstract is Oscillatory Network Mapping of Deep Brain Stimulation Outcomes in Parkinson's Disease.
Now, to be honest, I only had access to the abstract, as you know, and it seems very novel and also quite complicated, especially in the analysis. Can you guide us through the methodology and the main results of the study?
[00:04:20] Dr. Bahne Bahners: Sure. Yeah. So basically working with Andreas Horn brought me to that topic a bit. The idea was that if we're able to map DBS outcomes using fMRI and structural MRI based on the electrode location, so calculating connectivity of the DBS electrode to any other brain region using a normative connectome.
So FMRI connectome, for example, where we have an FMRI time series for the electrode, and then for each other region of the brain, we can say, okay, this particular spot where the electrode is stimulating is connected to the other [00:05:00] regions of the brain in a certain way. And this methodology is established already and has been shown in many publications work to estimate DBS outcomes. So what we wanted to use electrophysiology, where we don't only have a static image at one particular point in time, or a very slow time series in fMRI, but can actually resolve These time dynamics that are important in Parkinson's disease, for example beta band changes, which have been shown to be very important.
So we really wanted to address this issue of the temporary solution for DBS network mapping as it has been done before. The idea was we take this huge data set we have in Dusseldorf in Berlin, which is unique because we collect data from the DBS electrode where we have LFP recordings on the day after surgery, where [00:06:00] DBS electrodes are externalized.
And record cortical activity using MEG the same day in parallel. And this is a unique opportunity to look at the actual electrophysiological connectivity between the stimulation side of the DBS electrode and all of the other cortical regions. And that can only be done if you have these combined recordings, of course.
And to make use of that, we then calculate the The coherence between the local field potential time traces. and the cortical time courses. Coherence is a correlative measure or a correlation of signals in the frequency domain. And that gives us an idea of how the STN is electrophysiologically connected to the rest of the brain.
We hypothesize that that connectivity pattern would be helpful to estimate which patient responds well and which [00:07:00] patient doesn't respond well. So what we did was we calculated the coherence for each of the DBS electrodes, which were across the two cohorts we have in Dusseldorf in Berlin, 100 DBS electrodes.
And we calculate the coherence to the cortex and use that coherence as a map, the oscillatory network map for each individual electrode. These individual maps are then correlated with, so in each voxel, this map is correlated with the DBS outcomes. So the UPDRS percentage improvement one year after surgery for each of these 100 electrodes.
So what we get is in each voxel, a correlation between these 100 voxel coherence values at the cortex and the 100 UPDRS improvements. And that gives us a correlation value for every voxel in the brain. And this correlation tells us how [00:08:00] well this oscillatory connectivity or the coherence correlates with the UPDRS outcome.
So we at the end get a map that shows us which regions are mostly correlated to DBS outcome in which of the frequency bands. And we create multiple maps for multiple frequency bands and also do that for symptom specific outcomes.
[00:08:28] Dr. Michele Matarazzo: Okay. And what did you find? I mean, what does this map look like?
[00:08:33] Dr. Bahne Bahners: So, First of all, the, the coherence map as in the grand average across patients looks exactly as we expected. And as we have seen in the studies before, so the theta alpha connectivity network has a frontal, and temporal pattern, which has been described earlier. So the coherence of STN signals is strong in the theta alpha band to temporal and frontal areas [00:09:00] in the beta band be it low or high beta, we see strong coherence to the motor regions.
And that has been shown before. If we now look at the correlation maps, so the maps that show us which regions are relevant for the BS outcomes, we see that. low beta and high beta maps actually differ. And even though the grand average is very similar. So the low beta map shows a positive correlation across the motor strip while the high beta map shows a negative correlation across the motor strips.
And this relationship gets even stronger if we only look at Bradykinesia, for example. So for Bradykinesia, The high beta map has a very strong negative correlation across central areas, which is not that apparent if we look at the total UPDRS, for example,
[00:09:50] Dr. Michele Matarazzo: And did you just maybe didn't look at that, but did you find something if you just look at the tremor specifically?
[00:09:57] Dr. Bahne Bahners: yes, if we look at the tremor specific [00:10:00] correlation map, we were able to see a very strong positive correlation in central and frontal regions in the theta alpha band, which would be in line with previous knowledge on The Tremor Network and the Theta Alpha band and would make sense in this, in this regard.
[00:10:18] Dr. Michele Matarazzo: Okay. Now, how do you think these results will impact, the future treatment options for Parkinson's disease.
[00:10:27] Dr. Bahne Bahners: So this project is still ongoing. We'll have to see if we're able to validate the maps in our second cohort and the external cohort that we also, that we got from our colleagues in Berlin. And if that holds true, and it looks as if this high beta finding might be promising for bradykinesia, there could be an option to translate that into easier more applicable imaging methodology.
So not using MEG because it's very, very rare across centers. So if we would want to transfer that to clinical practice, we [00:11:00] would definitely need to try that next with EEG. So having combined LFP, EEG recordings, potentially even with the novel sensing enabled DBS devices where we can record both local field potentials and cortical signals, and then look at the pattern.
And if we find One of the four DBS contact levels, for example, a pattern that resembles our map a lot, that would potentially be the best or the optimal DBS contact. And that could be a way to find the optimal DBS settings and in some of the patients potentially.
[00:11:35] Dr. Michele Matarazzo: Okay. So you kind of use a map as a biomarker to define which are the best tuning of DBS in a given patient. Right?
[00:11:46] Dr. Bahne Bahners: Exactly. Yeah.
[00:11:48] Dr. Michele Matarazzo: Well, that sounds really interesting. Now, when are we going to see the paper published? Because this is just the abstract, but when do we expect to see this out?
[00:11:59] Dr. Bahne Bahners: [00:12:00] So we're about to to finish the validation in the external cohort. It's a bit difficult to say how long that takes and if we need another validation step. But yeah, I, I hope that by the end of next year, it will be published. But it's still ongoing progress. Yeah.
[00:12:18] Dr. Michele Matarazzo: Now, what are the next steps in this specific project? I mean, apart from the things that you're already explained if you have other ideas to expand this project to study LFB in the brain simulation and maybe the use of cortical mapping along with that and also what are the next steps in your career?
How do you envision your career in the next few years?
[00:12:40] Dr. Bahne Bahners: So besides that project we have another important project going on with DBS evoke potentials where we actually engage with the network and that works very well and perhaps even a bit better than the resting state data I present here in that abstract and that could just be Be related to the fact that we actually [00:13:00] engage with the network when we record DBS evoke potentials.
So that project is is a bit closer even to publication and we'll you'll hear about that soon, hopefully. And then together with that MEG project, the resting state project I'd envision to develop Some kind of an electro physiological examination after DBS surgery that could help us to program patients a bit faster, potentially combining both methods.
So having an EEG recording together with LFPs, as well as DBS evoke potentials and determine which contact is the best for that patient To just improve this very lengthy process of DBS programming. So that would be my scientific perspective or aim in that regard. And then I need to go back to Germany soon.
So by the end of the year, my contract ends here and I will have to finish my, I want to finish my residency in neurology in Germany. to also be able to treat patients because I love that [00:14:00] as much as I love research. So I definitely have
[00:14:03] Dr. Michele Matarazzo: So you're gonna, you're gonna do both things. So you're going to be a clinical scientist to do both things, right? Well, this is great. Congrats again for the award. I really look forward to hearing more from you and your work in the future. Thank you again for joining me today.
[00:14:20] Dr. Bahne Bahners: Thank you so much.
[00:14:21] Dr. Michele Matarazzo: Our guest today has been Dr. Bahne Bahners, who is currently a research fellow at the Brigham and Women's Hospital and Harvard Medical School in Boston, who is one of the recipients of the International Parkinson's and Movement Disorders Society Junior Award for 2024. Thank you all for listening. [00:15:00]