iiinova — where your digital self keeps evolving

As always all the data are openly available through ONE (int-brain-lab.github.io/ONE/). This work was spearheaded by Rosa Großmann (@rosacg.bsky.social) with help from Jorge Meijas (@jorgefmejias.bsky.social), Zach Mainen (not on bluesky), and the IBL collaboration (@intlbrainlab.bsky.social).

Computational modelling revealed that the cortical DOWN state is global. The visual cortex does not receive direct dorsal raphe input, but is still transitioned into a DOWN state. The 5-HT induced DOWN state is widespead enough that the visual cortex is pulled into it by the rest of the brain.

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Looking at the spike rasters across the entire probe we saw that 5-HT stimulation resulted in a DOWN state. To quantify this effect we fit a two-state HMM and found 5-HT induced DOWN states everywhere except the midbrain.

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To answer these questions we did large-scale Neuropixel recordings across the anesthetized mouse forebrain while optogenetically stimulating dorsal raphe serotonergic neurons. We found that spiking activity across the brain was suppressed by serotonin stimulation.

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Serotonin induces DOWN states across the anesthetized mouse forebrain

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

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 😃

Guido Meijer @guidomeijer.com · 07/07/2026

I find that a ritual sacrifice to the ephys gods before each recording also helps

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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 · 30/06/2026

Turned out I didn't need an app and was up at 5:30 anyway due to said toddler 🙃

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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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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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Guido Meijer @guidomeijer.com · 07/05/2026

Thank you! Here is the code I wrote to pull the data from the Allen Brain Atlas: github.com/guidomeijer/... And here is the code to create the website: github.com/guidomeijer/...

github.com

SerotoninStimulation/Figures/figure3/get_receptor_expression_per_region.py at master · guidomeijer/SerotoninStimulation

Contribute to guidomeijer/SerotoninStimulation development by creating an account on GitHub.

Guido Meijer @guidomeijer.com · 07/05/2026

Select a receptor subtype in the dropdown menu on the left ("Select a feature"). You can scroll through the views with the sliders underneath. You can also scale the colormap by going to "Control Panel" on the top right and changing the sliders sliders underneath "colormap range".

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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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What can we do? The current approach is to accept that these people need constant rescuing. This policy needs to shift to a more preemptive approach, why do these people make decisions like a five year old? How can we help them become better at this? Any suggestions are welcome.

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The residents of Pontypandy make terrible decisions leading to a high incidence of forest fires and the likes. My fear is that the entire budget for fire and rescue services of Wales is being spend on saving the ten people who live their over and over.

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Then there is the issue of mass surveillance around the town. When something goes wrong, an AI system knows exactly what is happening and where. Even when nobody calls them. This is only possible through ubiquitous camera coverage with facial recognition software, these people have no privacy!

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The fire and rescue services of Pontypandy are extremely advanced. Besides regular fire engines they have two helicopters, a tiltrotor, a hovercraft, drones, and several boats. Who is paying for all this? The tax burden for these poor people must be astronomical to afford all this kit.

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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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ERC backtracks on stricter grant resubmission rules

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

The swift reversal came after more than 1,000 scientists signed an open letter protesting the stricter rules last week.

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Reposted by Guido Meijer

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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Reposted by Guido Meijer

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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Guido Meijer @guidomeijer.com · 18/04/2026

Yep that's me, with excellent / outstanding reviews as well 🥲

PCI Neuroscience @neuro.peercommunityin.org · 18/04/2026

Reposted by Guido Meijer

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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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 · 21/10/2025

Thanks! I always save the illustrator file as an editable pdf, that way it is self contained even when the panels are technically links.

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Guido Meijer @guidomeijer.com · 21/10/2025

Thanks! Yes, that's a good way of doing it if you don't like Illustrator, I just find it way too time consuming to position everything programmatically (and I have free Adobe through my uni 😁)

I didn't know that, that's cool!

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colab.research.google.com

I hope you found this useful! Here is a Google Colab with example code of what was discussed in this thread: colab.research.google.com/drive/1UlCET...

Google Colab

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The workflow: Python plots single panels, saved as pdfs. Create an empty figure of 7 inch (180 mm) wide in Illustrator and place the panels as links. Add the panel letters (a,b,c). Now, if a new version of a panel is generated you just have to click update links in Illustrator and it's there. 🤩

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A note about colors 🌈 Imagine you made eight figures and your PI asks you to change the color of an element you've consistently plotted green into orange. If you define your colors in the plotting function you only have to change it there and rerun the plotting scripts, this save a lot of time!

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