I’m interested in how the brain shapes experience & experience shapes the brain. 👨🏻‍💻🔬🧠🏔️

Zurich, Switzerland
Joined March 2007
Simultaneous electrical and optical recording of brain activity can reveal aspects of brain function invisible to a single method. See why we think this combination offers many exciting possibilities. With @HoffmannNeuro and @FritjofHelmchen @SPIEtweets spiedigitallibrary.org/journ…
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Replying to @BachFrancis
(1/7) I'd like to provide some additional context for the remarks that can be found in this interview. (2/7) My discomfort with the attention being paid to existential risk---and with the ongoing dominance of the public discussion of such risks by a few so-called thought leaders---is that there's an elephant in the room that is being missed. That elephant is the effect of all of this discussion on young people, and indeed the effect---beginning with social media a decade ago---of information technology on young lives broadly speaking. (3/7) I recently read an interview by Jill Lepore in which she reports on discussions that she had recently with a group of college students: "They had just three things to say. One, social media completely destroyed their childhoods. Two, AI is destroying their college education and their likely prospects for employment. And three, what the hell are we all doing?" To add a fourth bullet that I've heard in similar discussions: "I'm not going to have children, because the existential risk is just too high." (4/7) Please contemplate such a statement, those of you who think that it's OK that the public, widely diffused, discussion coming from seemingly authoritative figures is so adamant about existential risk. (5/7) Let me add that I have little interest in a debate about what "superintelligence" might mean, or whether we're currently seeing the emergence of superintelligence. For what it's worth, I would certainly agree that the solution of extremely challenging math problems (for example) exhibits a very impressive form of intelligence, although I would want to argue that such intelligence is impossible to dissociate from the collective of humans that provided data to the machine learning system (which itself has become a kind of collective). (6/7) Such philosophical debates are entertaining and even important, but when they then head in the direction of "when such superintelligence emerges, there's a good chance that it will want to kill all humans", I say "science fiction". Again, I don't think that it's bad to consider such thoughts, but I strongly believe that it's bad for society, and especially young people, for such thoughts, unaccompanied by any serious real-world analysis, to become a dominant form of discourse of the era. (7/7) We are damaging human lives, and the consequences of that damage will no doubt be a major theme of the next several decades.
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I wrote down my thoughts about the last several weeks of AI hell. ⬇️
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While walking to work, I just had a chat with ChatGPT to make sure I understood what the claimed singular solution to Navier-Stokes would mean *physically.* Here's a tweet thread it generated for me. Hope you find it helpful. (I rewrote it a bit to clarify what's surprising.)
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The largest experimental protein sequence-fitness dataset: 13k measurements across 3 proteins reveals that fitness landscapes are rugged, there are many functional sequences between orthologs, and current ML models can't distinguish functional and non-functional sequences.
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If you are interested in combining 2p imaging with chronic electrophysiology this may be of interest. Very happy and proud about this long-term team effort! Kudos especially to @a_roggenbach and Linus!
⚠️PREPRINT ALERT⚠️ How can we better understand distributed brain activity across temporal and spatial scales? In this collaborative project, we combined ultra-flexible electrodes with two-photon imaging to illuminate brain-wide neural dynamics. doi.org/10.21203/rs.3.rs-102… 1/8
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⚠️PREPRINT ALERT⚠️ How can we better understand distributed brain activity across temporal and spatial scales? In this collaborative project, we combined ultra-flexible electrodes with two-photon imaging to illuminate brain-wide neural dynamics. doi.org/10.21203/rs.3.rs-102… 1/8
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Today, I would like to honor the memory of Roger Y. Tsien, who died on August 24, 2016. His legacy lives with all who use his technologies, including calcium sensors, fluorescent proteins, the acetoxymethyl (AM) ester, & many more! #FluorescenceFriday nature.com/articles/nmeth.40…
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Eclipse 12/8/26 Zürich
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Layer-specific wide-field calcium imaging of neocortical activity
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We developed a hybrid micro-ECoG array combining the best features of polyimide and silicone. Polyimide enables high electrode density, while silicone is soft and transparent. The array enables high resolution functional mapping in combination with optical methods. (link below)
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I went to the (great) workshop in Leiden that led to the Leiden Declaration, but ended up not signing it, as it didn't really represent my views, though it wasn't too different either, so the decision wasn't an obvious one. I've explained more in a blog post. Link in next tweet.
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chris lewis retweeted
Replying to @astrodanish
Motor neuroprosthetics (cursor/speech/handwriting in the plot) could theoretically reproduce the bandwidth of the motor system but not exceed it. A small exception is the ~10-100ms delay for CS cell -> motor neuron latency, but that screws up efferent comparators, etc., so limits to open-loop; the ITR bump is negligible. Would you rather have 10k electrodes positioned sparsely throughout cortex (and maybe some deeper brain structures) or 100k electrodes densely packed in M1 hand knob? Bandwidth caps at the mutual information the neural signal carries about the decoded variable (likely bounded by the dimensionality of the motor state). A new electrode only buys you its conditional MI given the channels you already have. In low-D areas like M1 hand knob, that conditional information collapses toward zero at high channel count (you keep averaging down noise on the same latents, but get nothing new). Brute forcing more electrodes in these motor paradigms won't be enough. Much much more to say on this, ofc. Will eventually get around to sharing more publicly.
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It can be tempting to extrapolate the increasing capabilities of electrode-based motor BCIs and claim they’ll enable superhuman performance in a few years. This paper is one reason to suggest there is a “speed limit” to consider. science.org/doi/10.1126/scia…
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chris lewis retweeted
NIH grants have been under political scrutiny since 2025. But what does the screening process actually look like? For @nature, I spent a month digging into leaked docs. We've published a list of 235 words being flagged by an internal AI tool. And so much more. 🧵
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Barcelona bike infrastructure is great.
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