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Guido Meijer

@guidomeijer.com
1.8K followers 620 following 182 posts

👨‍🔬 Neuroscientist at the Donders Institute in the Battaglia lab. 🧠 Previously: International Brain Laboratory Using Neuropixels and virtual-reality to understand how the brain creates internal models of the world. www.guidomeijer.com

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Guido Meijer @guidomeijer.com · 25/09/2026
Distributing grants through a lottery has its advantages but I'm afraid it will result in even more AI generated grant applications. A lottery is a good idea but it has to be taken one step further to really work: no more grant proposals at all anymore. www.thetransmitter.org/funding/gran...
thetransmitter.org
How about adding an element of chance to grant review?
A process that uses a lottery system saves time and accepts that, above a quality threshold, luck has always played a part in science funding.
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Guido Meijer @guidomeijer.com · 16/09/2026
Let me tell you, teaching a course to first year undergrads is a sure-fire way of making you feel really, really old.
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Guido Meijer @guidomeijer.com · 05/08/2026
It was great to see the RIKEN institute in Japan and give a talk there. Thanks to Muhang Li and @tommchugh.bsky.social for inviting me!
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Guido Meijer @guidomeijer.com · 31/07/2026
If you're attending the NEURO2026 conference in Kobe, Japan ⛩️ don't miss our symposium on Sunday morning about the latest from the IBL @intlbrainlab.bsky.social. My talk on how neuromodulators shape decision-making starts at 09:55 🧠
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Guido Meijer @guidomeijer.com · 21/07/2026
I am happy to announce my very first senior author paper! Serotonin is known to abolish UP-DOWN state dynamics, which occur during sleep and anesthesia. There are several outstanding questions: What happens at short latencies? How widespread across the brain is it? 🧠 www.biorxiv.org/content/10.6...
biorxiv.org
Serotonin induces DOWN states across the anesthetized mouse forebrain
Serotonergic neurons in the dorsal raphe nucleus (DRN) project extensively throughout the forebrain, yet their influence on global network states remains controversial. Serotonin is implicated in regu...
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Guido Meijer @guidomeijer.com · 16/07/2026
Now that my daughter can say a few words I feel like being a servant to a neanderthaler. I'm constantly being shouted at "food!", "give!", "yes good, more more!"
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Guido Meijer @guidomeijer.com · 10/07/2026
I wonder which layer of hell Dante reserved for the developers of the FENS app
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Guido Meijer @guidomeijer.com · 07/07/2026
Thanks to all who visited my poster for your interest and lively discussions 😃
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Guido Meijer @guidomeijer.com · 06/07/2026
I'm on my way to Barcelona for #FENS2026! 🌞🧠Come see my poster tomorrow morning: PS01-07AM-292 - DYNAMIC UPDATING OF REWARD PREDICTIONS BY THE PARA-HIPPOCAMPAL NETWORK I did simultaneous Neuropixel recordings in CA1 and 5 cortical regions to find out how the brain switches between cognitive maps 🗺️
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Carl Zimmer @carlzimmer.com · 01/07/2026
Meet SpudCell, a synthetic cell made from lifeless ingredients that feeds, grows, divides, and experiences selection. If it doesn't have all the hallmarks of life, it has a lot! Here's my story. Gift link: nyti.ms/4vCbTih
A series of images of a dividing synthetic cell
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Guido Meijer @guidomeijer.com · 28/06/2026
Idea for an app!💡 World Cup football matches are often in the middle of the night for us Europeans; the Netherlands is playing at 3AM 💤 I want an app that wakes me at 5:30AM to see the penalty shoot outs, but only if there are any. Can someone who doesn't have a 2 year old develop this? Thanks! 🙏🏻
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Guido Meijer @guidomeijer.com · 12/06/2026
I wonder how many unnecessary figure panels have been made just to make the entire figure nice and rectangular.
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Guido Meijer @guidomeijer.com · 09/06/2026
Want your mice to learn your task faster? 🐭 According to this paper giving a huge reward (10x typical size) in a subset of trials strongly shortens training times: www.science.org/doi/10.1126/...
science.org
Reward magnitude determines reinforcement learning efficiency
Standard animal learning studies minimize individual reward magnitudes to maximize the repetitions of reinforced behaviors. We investigated how reward magnitude influences initial learning across five...
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Kenneth Harris @kenneth-harris.bsky.social · 21/05/2026
Introducing the International Brain Lab AI Agent: a tool to help researchers analyze neural activity from across the mouse brain, using AI coding agents. Please try it! We would love your feedback. github.com/int-brain-la...
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Guido Meijer @guidomeijer.com · 15/05/2026
zetapy v4.0 is live! Due to various optimizations of the code it now runs 4x faster⚡Upgrade now and get your significant neurons in no time! pip install zetapy==4.0
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Tyler King @tyleraking.com · 09/05/2026
This website shows you what your browser is leaking about you. sinceyouarrived.world/taken
sinceyouarrived.world
taken.
A web page that tells you what your browser gave away the moment you arrived. No login, no form, no permission. Most pages do this. None of them tell you.
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Guido Meijer @guidomeijer.com · 07/05/2026
Are you interested in serotonin receptors? I made a website which visualizes the expression of different 5-HT receptors! Data from the Allen Brain Atlas (@alleninstitute.org) website by the IBL Brain Viewer (@intlbrainlab.bsky.social). atlas.internationalbrainlab.org?buckets=meij... Instructions 👇
atlas.internationalbrainlab.org
IBL Brain Atlas
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Guido Meijer @guidomeijer.com · 05/05/2026
I've been watching Fireman Sam with my daughter (the new animated version) and I must say I'm deeply worried for the residents of Pontypandy, the small Welch village with a population of apparently 10 people. A thread 🧵
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Guido Meijer @guidomeijer.com · 05/05/2026
I'm very happy that fairness and reason has prevailed and the ERC has backtracked on this. Thanks to everyone who signed the open letter to the ERC for making this happen 🙏🏻 www.thetransmitter.org/policy/europ...
thetransmitter.org
ERC backtracks on stricter grant resubmission rules
The swift reversal came after more than 1,000 scientists signed an open letter protesting the stricter rules last week.
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Pierre Le Merre @pierrelemerre.bsky.social · 01/05/2026
So I (well Claude mostly) made a @julialang.org port of the ZETA test originally developped by Jorrit Montijn (published here: elifesciences.org/articles/71969). The port is faithful to zetapy (Python version by @guidomeijer.com and @alexanderheimel.bsky.social). Enjoy github.com/PierreLeMerr...
github.com
GitHub - PierreLeMerre/ZetaJu
Contribute to PierreLeMerre/ZetaJu development by creating an account on GitHub.
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Fabian Sinz @sinzlab.bsky.social · 24/04/2026
🧠Introducing OmniMouse: One of the largest datasets in neuroscience along with a systematic study of scaling properties of brain models Co-led by 🤩 K. Willeke, @pollytur.bsky.social and @alexrgil14.bsky.social Models trained on up to 3M neurons, >150B tokens
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Kate Jeffery @katejj.bsky.social · 21/04/2026
Job alert! We are seeking a rodent in vivo electrophysiologist to work on coordination between anterior thalamus and hippocampus in rats using Neuropixels. Beautiful Scotland, leading university (Glasgow) and vibrant intellectual setting. Post is 23 months but hopefully extensible. Details here 👇
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PCI Neuroscience @neuro.peercommunityin.org · 18/04/2026
Do you record spikes in vivo? Here are two recently recommended preprints on toolboxes for extracellular electrophysiology: -MLIB doi.org/10.1101/2025... by Maik Stüttgen. -Power Pixels doi.org/10.1101/2025... by @guidomeijer.com and @battaglialab.bsky.social.
doi.org
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Guido Meijer @guidomeijer.com · 17/04/2026
The ERC is changing the rules retroactively! A "B" grade now carries a 2-year timeout instead of 1, even for those who submitted under the old rules. Researchers (incl me) make massive career decisions based on these timelines, you can't change them after the fact 😵‍💫 erc.europa.eu/news-events/...
erc.europa.eu
ERC President explains stricter application measures amid rising demand for funding
The text of an open letter sent by ERC President Maria Leptin to ERC panel members, grantees and other stakeholders on 16 April 2026.
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Guido Meijer @guidomeijer.com · 26/02/2026
The Power Pixels ⚡ pipeline is out now in Peer Community Journal! Are you doing Neuropixel recordings but don't have a pre-processing pipeline yet? Check out this end-to-end pipeline designed to simplify preprocessing of Neuropixel recordings 🧠 peercommunityjournal.org/articles/10....
peercommunityjournal.org
Power Pixels: a turnkey pipeline for processing of Neuropixel recordings
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Pierre Le Merre @pierrelemerre.bsky.social · 20/01/2026
Main postdoc study out! We can redefine prefrontal cortex regions with single-unit activity! Grateful to @carlenlab.bsky.social and @weltgeischt.bsky.social who made this crazy project real. Thanks to all co-authors, collaborators, and reviewers. www.nature.com/articles/s41...
nature.com
A prefrontal cortex map based on single-neuron activity - Nature Neuroscience
The authors mapped spontaneous and choice activity across mouse prefrontal cortex. The activity maps aligned with intrinsic connectivity rather than anatomical subregions, suggesting that connectivity...
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Valentin Riedl @vavatin.bsky.social · 16/12/2025
fMRI signals “up,” but neural metabolism might be going “down.” In our @natneuro.nature.com paper, we demonstrate that about 40% of voxels with robust BOLD responses exhibit opposite oxygen metabolism, revealing two distinct hemodynamic modes. rdcu.be/eUPO8 funds @erc.europa.eu #neuroskyence 🧵:
BOLD signal changes can oppose oxygen metabolism across the human cortex, Nature Neuroscience
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Guido Meijer @guidomeijer.com · 11/11/2025
The Power Pixels pipeline just keeps getting better! The latest update comes with: - OpenEphys support - AP_Histology support - automatic high-frequency noise reduction - NWB format export option - zarr compression of raw data And, most importantly: a cool new logo! github.com/NeuroNetMem/...
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Guido Meijer @guidomeijer.com · 31/10/2025
Halloween isn’t my thing. My idea of a scary night is reading the plots of horror movies on Wikipedia.
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Guido Meijer @guidomeijer.com · 25/10/2025
I never understood why everyone always complains about the clocks changing. Then I had a kid.
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Guido Meijer @guidomeijer.com · 16/10/2025
Want to make publication-ready figures come straight from Python without having to do any manual editing? Are you fed up with axes labels being unreadable during your presentations? Follow this short tutorial including code examples! 👇🧵
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Guido Meijer @guidomeijer.com · 08/10/2025
I was doing the second-to-last recording of my project and was happily thinking to myself that I haven't broken a single Neuropixel in the entire two year project. You can guess what happened next... Now I have to install a new probe just for one final recording 🙃
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Guido Meijer @guidomeijer.com · 05/10/2025
I love how they came up with all this random stuff but for this one area they were like "I really don't know, just put a question mark"
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Guido Meijer @guidomeijer.com · 20/09/2025
When I told my dad I published in Nature he was like "wow, you must have made a lot of money with that"
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Guido Meijer @guidomeijer.com · 12/09/2025
I don't know why people say X is going down the drain, my last post got lovely replies like this one:
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International Brain Laboratory @intlbrainlab.bsky.social · 11/09/2025
Want to collaborate with the International Brain Laboratory on your own project? We have funding to work with groups anywhere in the world to do new large-scale projects and we are looking for new partners! Learn more and apply: www.internationalbrainlab.com/ibl-core-apply
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Emilie Macé @mace-lab.bsky.social · 11/09/2025
Thrilled to share that our work is now published in Science! ✨ We found a preference for visual objects in the mouse spatial navigation system where they dynamically refine head-direction coding. In short, objects boost our inner compass! 🧭 www.science.org/doi/10.1126/... 🧵1/
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Matteo Carandini @carandinilab.net · 09/09/2025
If you're into podcasts, here's a good one on the @intlbrainlab.bsky.social brainwide map, by @newscientist.com www.newscientist.com/podcasts/fir...
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Ben Hayden @benhayden.bsky.social · 04/09/2025
Sad day for peope who still believe brain areas are the primary organizational units of function in the brain. www.nature.com/articles/s41...
nature.com
A brain-wide map of neural activity during complex behaviour - Nature
The International Brain Laboratory presents a brain-wide electrophysiological map obtained from pooling data from 12 laboratories that performed the same standardized perceptual decision-making task i...
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Simons Foundation @simonsfoundation.org · 03/09/2025
The ‪@intlbrainlab.bsky.social published 2 papers today on their work to create a map of neural activity across the entire mouse brain. Learn more about the lab: www.simonsfoundation.org/2025/02/20…
simonsfoundation.org
How Do Our Brains Make Decisions? The International Brain Laboratory Is Closing In on Answers
How Do Our Brains Make Decisions? The International Brain Laboratory Is Closing In on Answers on Simons Foundation
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New Scientist @newscientist.com · 03/09/2025
The first complete activity map of a mammalian brain has revealed unprecedented insights into how decisions are made – and may even hint at the roots of intuition.
newscientist.com
First map of mammal brain activity may have shown intuition in action
Scientists have mapped the activity that takes place across a mouse's entire brain as it decides how to complete a task - and the results could explain the origin of our gut feelings
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Guido Meijer @guidomeijer.com · 03/09/2025
Extremely proud to have contributed to this monumental effort of recording the entire mouse brain, at cellular resolution, during complex behavior 🧠🐭
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Guido Meijer @guidomeijer.com · 29/08/2025
PSA: don't buy duragel from Cambridge Neurotech, it's a scam! 🚨 They charge $200 (incl. shipping) for a 16 ml spout. But duragel is just DOWSIL 3-4680 (see paper below) of which you can buy a large container of 210 ml for only $110. That's 24 times cheaper! 💸 www.sciencedirect.com/science/arti...
sciencedirect.com
Artificial dural sealant that allows multiple penetrations of implantable brain probes
This study reports extensive characterization of the silicone gel (3-4680, Dow Corning, Midland, MI), for potential use as an artificial dural sealant…
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Guido Meijer @guidomeijer.com · 13/08/2025
Duct tape and hope are literally the only two things holding my rig together
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Guido Meijer @guidomeijer.com · 06/08/2025
Don't feel like reading? Check out my talk! www.youtube.com/watch?v=QIl6...
youtube.com
Guido Meijer - Serotonin modulates neural dynamics in a subspace orthogonal to the choice space
YouTube video by Guido Meijer
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Guido Meijer @guidomeijer.com · 05/08/2025
🚨Pre-print alert🚨 We stimulated serotonin with optogenetics while doing large-scale Neuropixel recordings across the mouse brain. We found strong widespread modulation of neural activity, but no effect on the choices of the mouse 🐭 How is this possible? Strap in! (1/9) 👇🧵 doi.org/10.1101/2025...
doi.org
Serotonin drives choice-independent reconfiguration of distributed neural activity
Serotonin (5-HT) is a central neuromodulator which is implicated in, amongst other functions, cognitive flexibility. 5-HT is released from the dorsal raphe nucleus (DRN) throughout nearly the entire f...
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Guido Meijer @guidomeijer.com · 31/07/2025
Was watching Clarkson's Farm and kept wondering how AI was going to help them get calves only to realize it stands for artificial insemination
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Guido Meijer @guidomeijer.com · 04/07/2025
Just added Bombcell 💣 to the suite of automatic curation tools that's included in the Power Pixels pipeline! It runs Bombcell, UnitRefine and the IBL algorithm to classify which of your units are good single neurons. You can can then use one (or more!) of these to filter your units before analysis.
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Julie Fabre @juliefabre.bsky.social · 13/06/2025
🚀 We are excited to share that bombcell is now available in Python! 🐍 Automatically sort your units into good/MUA/noise/non-somatic using quality metrics and interpretable & adjustable classification thresholds. pip install and play around with our toy dataset: 🔗 github.com/Julie-Fabre/...
github.com
GitHub - Julie-Fabre/bombcell: Automated quality control, curation and neuron classification of spike-sorted electrophysiology data
Automated quality control, curation and neuron classification of spike-sorted electrophysiology data - Julie-Fabre/bombcell
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Guido Meijer @guidomeijer.com · 01/07/2025
Do you do Neuropixel recordings and are you struggling with preprocessing? The Power Pixels pipeline is an easy-to-use pipeline from raw data to neural activity of single neurons in specified brain regions 🧠 Now on bioRxiv! www.biorxiv.org/content/10.1...
biorxiv.org
Power Pixels: a turnkey pipeline for processing of Neuropixel recordings
There are many open-source tools available for the processing of neuronal data acquired using Neuropixels probes. Each of these tools, focuses on a part of the process from raw data to single neuron a...
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