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!

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 🧠

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...

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...

biorxiv.org

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!"

I wonder which layer of hell Dante reserved for the developers of the FENS app

Thanks to all who visited my poster for your interest and lively discussions 😃

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 🗺️

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

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! 🙏🏻

I wonder how many unnecessary figure panels have been made just to make the entire figure nice and rectangular.

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/...

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...

science.org

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...

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

This website shows you what your browser is leaking about you. sinceyouarrived.world/taken

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.

sinceyouarrived.world

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 👇

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 🧵

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...

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.

thetransmitter.org

Guido Meijer@guidomeijer.com · 4mo ago

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/...

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 - PierreLeMerre/ZetaJu

Contribute to PierreLeMerre/ZetaJu development by creating an account on GitHub.

github.com

🧠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

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 👇

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.

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 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.

erc.europa.eu

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....

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...

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...

nature.com

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 🧵:

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/...

Halloween isn’t my thing. My idea of a scary night is reading the plots of horror movies on Wikipedia.

I never understood why everyone always complains about the clocks changing. Then I had a kid.

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! 👇🧵

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 🙃