Lucas C Parra

We believe healthcare is a right for every American.

But starting today, millions of people will be notified that they are being priced out of their insurance thanks to Republican policies.

Enough is enough. The GOP may shut down the government, but we will stand tall for YOU.

So flattering! Thanks @biophysicalsoc.bsky.social for this deeply meaningful award! All credit goes to my lab members and collaborators.
@scilifelab.se @ki.se

Trump's new H-1B fee won't apply to existing visa holders, official says The $100,000 fee for the highly prized visa is intended to boost jobs for U.S. workers.

... unnamed White House official says ... "It will first apply in the upcoming lottery cycle for new applicants.".

This sounds like it won't apply to cap-exempt H1B for academia, or will it?

Chaos and arbitrary rules, again.

www.axios.com/2025/09/20/t...

Does anyone know if this affects cap-exempt H1-B at academic institutions?

Fewer guns = fewer deaths
Simple fact.
We are the world outlier.

M1, not so low-d after all:
www.biorxiv.org/content/10.1...

And 93 of mine ...

Ultrasound system for precise neuromodulation of human deep brain circuits - Nature Communications Modulating deep brain structure can lead to therapies for neurological conditions. Here, the authors show a transcranial ultrasound stimulation (TUS) system featuring a 256-element helmet-shaped trans...

This is a very impressive system. Ultrasound brain stimulation with 256 transduces and simultaneous fMRI. Results suggest focal stimulation of LGN, a visual nucleolus deep inside the brain.

www.nature.com/articles/s41...

The Path

Opinion | Bernie Sanders: Kennedy Must Resign

The time between fucking around and finding out for messing with the climate and environment is long, and attribution is sometimes difficult. So conservative politicians have gotten away with appointing imbeciles to positions of power in these areas. However, no such luck for them in public health.

This rule would have meant I couldn't do my Ph.D. in America.

I did do it in America. Became a professor. 12 thriving U.S. labs are now headed by trainees from my research lab. Like me, they are all working hard to enrich American knowledge and society.

With this self-harming rule, none of that.

Opinion | Bernie Sanders: Kennedy Must Resign

Bernie Sanders: Kennedy Must Resign www.nytimes.com/2025/08/30/o...

Replay in the human visual cortex during brief task pauses is linked to implicit learning of successor representations | PNAS Humans can implicitly learn about multistep sequential relationships between events in the environment from their statistical co-occurrence. Theore...

Delighted to share our work on replay and successor representations! We find replay during very short task pauses in human visual cortex that is linked to learning SRs & happens when learning is implicit. Study led by @lnnrtwttkhn.bsky.social

#compneuro #neuroskyence

www.pnas.org/doi/10.1073/...

Neural and behavioral reinstatement jointly reflect retrieval of narrative events - Nature Communications When people recall a movie, their eye movements and brain activity resemble those observed during the viewing. These behavioral and neural reactivations are linked through a common process, likely ref...

Excited to share our new paper w/ @cibaker.bsky.social in @natcomms.nature.com linking active vision & memory!

We provide evidence that gaze reinstatement & neural reactivation are deeply related phenomena that jointly reflect the experiences constructed during recall. doi.org/10.1038/s414...
🧵1/9

Are top-down feedback connections enough for robust vision?

We found ConvRNN with top-down feedback exhibiting OOD robustness only when trained with dropout, revealing a dual mechanism for robust sensory coding

with @marco-d.bsky.social, Karl Friston, Giovanni Pezzulo & @siegellab.bsky.social

🧵👇

I had totally missed this development of "fast weight programming" (FWP). This review makes a fascinating connection between recurrent networks and transformers with FWP right between the two. Supper interesting.

CE-Letter to Congress Requesting Protection of Science Funding in the FY26 Budget To: The Honorable Members of the United States Congress Dear Honorable Senators and Representatives, We write in our individual capacities as U.S. citizens to urge you to prevent the far-reaching cons...

Please sign! Science funding got strong support from the Senate but is now in the House! docs.google.com/forms/d/e/1F...

Our study is out in Nature!
Using wireless Neuropixels we recorded hippocampal activity in freely flying bats and uncovered replay and theta(less) sweeps, revealing striking differences from classic rodent models.

👉 www.nature.com/articles/s41...

This new paper on memory of stories makes perfect sense to me: we remember those topics better that get more time in the narrative.

Nice work.

YouTube video by BBC News Investigating the killings of children in Gaza | BBC News

"The BBC World Service has compiled material on over 160 cases where children have been shot in Gaza, and found that in 95 cases the child was shot in the head or chest.

In most of these cases the victim was under 12 years old."

www.youtube.com/watch?v=TjP6...

Interestingly, they chose to keep the dynamic A constant. Friston et al. assume A to be modulated by the task. The assumption that the brain has (largely) constant dynamic is consistent with our findings in iEEG

elifesciences.org/articles/104...

We are finding the same in EEG. Preprint coming ...

Nice work modeling behavior and EEG as dynamical systems. The State space model is similar to the "dynamical causal model" (without all the fantastical claims). Their code seems to work well in high dimensions, whereas DCM has only been used in small problems, despite both using the EM algorithm.

The word “Research” is doing way too much work. We need separate words for “creating new verifiable knowledge” and “looking shit up on the internet”

Reliability and signal comparison of OPM-MEG, fMRI & iEEG in a repeated movie viewing paradigm Optically pumped magnetometers (OPMs) offer a promising advancement in noninvasive neuroimaging via magnetoencephalography (MEG), but establishing their reliability and comparability to existing metho...

How reliable is OPM-MEG, and how does it compare to other neuroimaging modalities? 🤔

In a new preprint with ‪@s-michelmann.bsky.social‬, we evaluate the reliability of OPM-MEG within & between individuals, and compare it to fMRI & iEEG during repeated movie viewing. 🧠

📄 doi.org/10.1101/2025...

Here is another idea from biology on how to make ANNs learn more efficiently during continual learning. Adjust weights in first layers early in development [to learn shared representations] and keep higher layers plastic for longer [to learn new tasks].

www.biorxiv.org/content/10.1...

I would go further, don't use EEG for localization. Why? Because the mixing matrix is not invertible. If you try it anyway, all you will get back is the assumptions you put in.

The problem with "prediction error encoding" is the part about "encoding".

But there is a ton of evidence for prediction error or novelty modulating sensory responses, e.g.
while people watch movies the entire brain seems to be modulated by surprise:
www.nature.com/articles/s41...

FDA-NIH Workshop: Reducing Animal Testing The FDA is hosting a workshop on reducing animal testing. The workshop is open to current FDA and NIH employees.

🧪 After the workshop on 7/7, the FDA and NIH are asking for public comments on implementing novel methodologies and other strategies to reduce the use of animal testing by 7/14:

www.fda.gov/news-events/...

Log-Normal Multiplicative Dynamics for Stable Low-Precision Training of Large Networks Studies in neuroscience have shown that biological synapses follow a log-normal distribution whose transitioning can be explained by noisy multiplicative dynamics. Biological networks can function sta...

Together with @repromancer.bsky.social, I have been musing for a while that the exponentiated gradient algorithm we've advocated for comp neuro would work well with low-precision ANNs.

This group got it working!

arxiv.org/abs/2506.17768

May be a great way to reduce AI energy use!!!

#MLSky 🧪

Southern Ocean current reverses for first time, signalling risk of climate system collapse A major ocean current in the Southern Hemisphere has reversed direction for the first time in recorded history, in what climatologists are calling a ...

Do you know how crazy the weather has been? It is about to get crazier.
www.intellinews.com/southern-oce...