Moritz Gerster

Our new preprint on promises and caveats of the extraction of M/EEG activity from ROIs is out (see more details in the reposted thread): www.biorxiv.org/content/10.6...

Huge thanks to @studenova.bsky.social, Ruben Eguinoa, Guido Nolte, @sparsity.bsky.social, Arno Villringer, and Vadim Nikulin!

#Neuroscience #Neurology #Neurophysiology #ParkinsonsDisease #DeepBrainStimulation #DBS #STN #LFP #NeuralEngineering #Neurotechnology #Neuromodulation #Aperiodic

𝐈𝐦𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧:

Mid gamma power is a promising medication-independent biomarker for adaptive deep brain stimulation—and it could be implemented in existing hardware (e.g., Medtronic Percept™ PC).

Open-access paper: doi.org/10.1016/j.eb...

𝐎𝐮𝐫 𝐚𝐩𝐩𝐫𝐨𝐚𝐜𝐡:

We used aperiodic broadband power and mid gamma as LFP proxies for subthalamic firing.

𝐑𝐞𝐬𝐮𝐥𝐭:

Aperiodic broadband power correlated with motor symptoms both OFF and ON medication. The same was true for mid gamma.

Increased firing could so far only be confirmed 𝗱𝘂𝗿𝗶𝗻𝗴 surgery using microelectrodes, in the absence of Levodopa medication.

Due to these technical constraints, most human studies have focused on beta and largely ignored the firing.

We know Levodopa reduces beta – but how does it affect firing?

Parkinson’s disease involves two major abnormalities in subthalamic nucleus activity:

1️⃣ Excessive beta (13–30 Hz) rhythms
2️⃣ Increased neuronal firing

Beta can be measured 𝗮𝗳𝘁𝗲𝗿 surgery using deep brain stimulation electrodes.

PS: This finding isn’t in the abstract and is easy to miss, so consider sharing it with colleagues working on automated DBS programming.

#Neuroscience #Neurology #Neurophysiology #ParkinsonsDisease #DeepBrainStimulation #DBS #STN #LFP #Neurotechnology #Aperiodic #CodeSharing #Reproducibility #SignalProcessing

𝐈𝐦𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧:

Absolute periodic high beta power could be used for automatic deep brain stimulation programming.

Horn et al. 2017: doi.org/10.1002/hbm....
Darcy et al. 2022: doi.org/10.1016/j.ex...
𝐆𝐞𝐫𝐬𝐭𝐞𝐫 𝐞𝐭 𝐚𝐥. 𝟐𝟎𝟐𝟓: doi.org/10.1016/j.eb...

1️⃣ Don’t normalize power spectra.
Absolute beta power (µV²/Hz) performs better than relative “% of total power.”
2️⃣ Remove the aperiodic component using specparam.
Isolating the periodic beta peaks improves the SNR.

The high beta maps shrink toward the therapeutic sweet spot (blue sphere in video).

𝐑𝐞𝐬𝐮𝐥𝐭:

Correlation with the clinical sweet spot improved from 𝐫 = −𝟎.𝟐𝟑 → 𝐫 = −𝟎.𝟒𝟓 with two key changes in signal processing:

𝐀𝐩𝐩𝐫𝐨𝐚𝐜𝐡:

Natasha kindly shared her analysis code, and I replicated her correlation between high beta power and the therapeutic sweet spot in an independent cohort (Darcy et al.: 𝐫 = −𝟎.𝟐𝟎; replication: 𝐫 = −𝟎.𝟐𝟑).

@andreashorn.org and @julianneumann.bsky.social proposed that the contact with the largest beta power in the STN could guide stimulation targeting.

Natasha Darcy corroborated this in a large cohort, and I wondered whether optimized signal processing could strengthen the result further.

Deep brain stimulation can improve Parkinson’s disease symptoms, but selecting the optimal stimulation contact still relies on laborious trial-and-error.

#Neuroscience #Neurophysiology #SignalProcessing #NeuralOscillations #Aperiodic #specparam #FOOOF

Full slide deck:

Even simpler, band-averaged gamma power closely tracked aperiodic broadband power (ρ = 0.93).

Taken together, the evidence suggests that invasively recorded gamma power can serve as a practical proxy for population firing.

Open-access paper: doi.org/10.1016/j.eb...

In our new paper, we separated oscillatory and aperiodic components and found that observed broadband shifts are mainly aperiodic – driven by flatter 1/f slopes and larger offsets.

Therefore, we termed it “aperiodic broadband power”.

Frustrated that I couldn’t measure firing directly in LFPs, I reviewed the studies that recorded both.

To my surprise, a consistent pattern emerged:

More firing → more broadband power.

Yet most of our macroscopic recordings — EEG, MEG, ECoG, LFPs — mainly reflect postsynaptic transmembrane currents, i.e., the inputs to neurons.

How do we reconcile measuring inputs while caring about outputs?

A neuron can only do two things: Fire. Don’t fire.

Firing is the neuron’s output, and most theories of neural computation treat that output as the brain's core information signal.

🧵

#reproducibility #openscience #Parkinson #deepbrainstimulation

Why?

This is beautifully visualized in Fig. 1b of this classic paper: doi.org/10.1038/nrn3...

In our recent publication, we show how scaling up to 119 patients across 4 hospitals strengthens biomarker discovery for adaptive deep brain stimulation in Parkinson’s disease: doi.org/10.1016/j.eb...

Imagine you run an experiment with 50 subjects and find a significant effect just below p < 0.05.

Another research group tries to replicate your finding, so they also recruit 50 people.

If your methodology was perfect, what’s the chance the replication succeeds?

95%? 80%?

It’s only 50% 🤯

👇🧵

Thank you @mpicbs.bsky.social for covering our study!

And thank you for fostering such an inspiring, intellectually vibrant, and genuinely supportive research environment — it was an exceptional place to do a PhD 🙏

Now out in @ebiomedicine.bsky.social!

📖 Read the open-access article: authors.elsevier.com/sd/article/S...

#Neuroscience #Neurology #Parkinsonsdisease #Parkinsons #DeepBrainStimulation #DBS #Neurotechnology #Neuromodulation #Neurophysiology #BasalGanglia #OpenScience #Reproducibility

YouTube video by Moritz Gerster Beyond beta rhythms - Moritz Gerster at DGKN Congress 2025

How does subthalamic nucleus activity relate to Parkinson’s disease symptoms?

My last 5 years of Parkinson’s disease research summarized in 5 minutes at the DGKN Congress 2025 :)
youtu.be/M9alDh836oU ⬇️

Full preprint: doi.org/10.1101/2025...

#Parkinsonsdisease #Parkinsons #DeepBrainStimulation