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Bill Podlaski

@billpod

Comp neuro @ Champalimaud

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15.11.2024
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Latest posts by Bill Podlaski @billpod

After several years of work, my lab is starting to put out our first papers on learning in a unicellular organism (Stentor coeruleus).

Here we show evidence for a form of associative learning in Stentor:
www.biorxiv.org/content/10.6...

26.02.2026 11:39 ๐Ÿ‘ 176 ๐Ÿ” 57 ๐Ÿ’ฌ 5 ๐Ÿ“Œ 7
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How can we build better experiment-theory collaborations in neuroscience?

We're hosting a series of 6 in-person, interactive workshops to discuss this.

Come along!

www.eventbrite.co.uk/e/understand...

26.02.2026 11:30 ๐Ÿ‘ 38 ๐Ÿ” 12 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 4
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Can we guarantee the behavior of an RNN to generalize well for infinite time? ๐Ÿง โ™พ๏ธ
Similar to universal approximation theorems in deep nets, for systems that forget everything eventually, there are guarantees. We prove it for multistable systems!
arxiv.org/abs/2602.08640 w/ @memming.bsky.social
(1/6)

12.02.2026 15:53 ๐Ÿ‘ 6 ๐Ÿ” 2 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 2
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Our paper is out in @natneuro.nature.com!

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

We develop a geometric theory of how neural populations support generalization across many tasks.

@zuckermanbrain.bsky.social
@flatironinstitute.org
@kempnerinstitute.bsky.social

1/14

10.02.2026 15:56 ๐Ÿ‘ 273 ๐Ÿ” 100 ๐Ÿ’ฌ 7 ๐Ÿ“Œ 1

neuroAI comparisons of ANNs to brains do have a range of problems. Even more than I had realized. And I was worried before: www.biorxiv.org/content/10.1...

09.02.2026 14:13 ๐Ÿ‘ 93 ๐Ÿ” 28 ๐Ÿ’ฌ 6 ๐Ÿ“Œ 4
Attention-like regulation of theta sweeps in the brain's spatial navigation circuit Spatial attention supports navigation by prioritizing information from selected locations. A candidate neural mechanism is provided by theta-paced sweeps in grid- and place-cell population activity, which sample nearby space in a left-right-alternating pattern coordinated by parasubicular direction signals. During exploration, this alternation promotes uniform spatial coverage, but whether sweeps can be flexibly tuned to locations of particular interest remains unclear. Using large-scale Neuropixels recordings in freely-behaving rats, we show that sweeps and direction signals are rapidly and dynamically modulated: they track moving targets during pursuit, precede orienting responses during immobility, and reverse during backward locomotion โ€” without prior spatial learning. Similar modulation occurs during REM sleep. Canonical head-direction signals remain head-aligned. These findings identify sweeps as a flexible, attention-like mechanism for selectively sampling allocentric cognitive maps. ### Competing Interest Statement The authors have declared no competing interest. European Research Council, Synergy Grant 951319 (EIM) The Research Council of Norway, Centre of Neural Computation 223262 (EIM, MBM), Centre for Algorithms in the Cortex 332640 (EIM, MBM), National Infrastructure grant (NORBRAIN, 295721 and 350201) The Kavli Foundation, https://ror.org/00kztt736 Ministry of Science and Education, Norway (EIM, MBM) Faculty of Medicine and Health Sciences; NTNU, Norway (AZV)

The hippocampal map has its own attentional control signal!
Our new study reveals that theta #sweeps can be instantly biased towards behaviourally relevant locations. See ๐Ÿ“น in post 4/6 and preprint here ๐Ÿ‘‰
www.biorxiv.org/content/10.6...
๐Ÿงต(1/6)

28.01.2026 10:03 ๐Ÿ‘ 183 ๐Ÿ” 62 ๐Ÿ’ฌ 4 ๐Ÿ“Œ 10
Grumpy from Disney's Snow White and the 7 dwarves.

Grumpy from Disney's Snow White and the 7 dwarves.

Let's talk about "grumpy lab person". Many labs have them. With an eye to keeping science at its most rigorous, they cross the line into criticism that's too harsh. They are the ones who risk killing your scientific spirit. They are reviewer 2. /1

21.01.2026 08:36 ๐Ÿ‘ 71 ๐Ÿ” 19 ๐Ÿ’ฌ 7 ๐Ÿ“Œ 6
Applications for 2026 entry to the Gatsby Bridging Programme (7-week maths summer school) will open on 19 Jan and close on 16 Feb. Designed for students who wish to pursue a postgrad research degree in theoretical neuroscience or foundational machine learning but whose degree programme lacks a strong maths focus. Applications from students in underrepresented groups in STEM strongly encouraged. A small number of bursaries available.
Register for the information webinar on 23 Jan.

Applications for 2026 entry to the Gatsby Bridging Programme (7-week maths summer school) will open on 19 Jan and close on 16 Feb. Designed for students who wish to pursue a postgrad research degree in theoretical neuroscience or foundational machine learning but whose degree programme lacks a strong maths focus. Applications from students in underrepresented groups in STEM strongly encouraged. A small number of bursaries available. Register for the information webinar on 23 Jan.

๐Ÿ“ข Applications open on 19 Jan for the 7-week #Mathematics #SummerSchool in London. You will develop the maths skills and intuition necessary to enter the #TheoreticalNeuroscience / #MachineLearning field.

Find out more & register for the information webinar ๐Ÿ‘‰ www.ucl.ac.uk/life-science...

15.01.2026 14:37 ๐Ÿ‘ 25 ๐Ÿ” 27 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 1

We are very excited to announce that our new preprint with Saleh Esteki, @stefanofusi.bsky.social, and @roozbehkiani.bsky.social is now available on biorxiv! www.biorxiv.org/content/10.6.... We investigated how reward context is learned, represented, and updated to bias decisions. Thread ๐Ÿงต๐Ÿ‘‡! 1/13

16.01.2026 22:15 ๐Ÿ‘ 25 ๐Ÿ” 10 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 1

Please spread the word๐Ÿ”ŠMy lab is looking to hire two international postdocs. If you want to do comp neuro, combine machine learning and awesome math to understand neural circuit activity, then come work with us! Bonn is such a cool place for neuroscience now, you don't want to miss out.

10.01.2026 17:39 ๐Ÿ‘ 33 ๐Ÿ” 37 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 1
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When and why do modular representations emerge in neural networks?

@stefanofusi.bsky.social and I posted a preprint answering this question last year, and now it has been extensively revised, refocused, and generalized. Read more here: doi.org/10.1101/2024... (1/7)

09.01.2026 19:06 ๐Ÿ‘ 76 ๐Ÿ” 18 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 2
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A Network of Biologically Inspired Rectified Spectral Units (ReSUs) Learns Hierarchical Features Without Error Backpropagation We introduce a biologically inspired, multilayer neural architecture composed of Rectified Spectral Units (ReSUs). Each ReSU projects a recent window of its input history onto a canonical direction ob...

Move over ReLU ๐Ÿš€
Meet **ReSU** (Rectified Spectral Unit): a biologically inspired, self-supervised unit for learning from dynamical data. A backprop-free multilayer ReSU network learns predictive features and recapitulates *Drosophila* vision.
To appear at AAAI: arxiv.org/abs/2512.23146

01.01.2026 16:27 ๐Ÿ‘ 27 ๐Ÿ” 10 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
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2025: A Review of the Year in Neuroscience Enlightening the brain

Just published my review of neuroscience in 2025, on The Spike.

The 10th of these, would you believe?

This year we have foundation models, breakthroughs in using light to understand the brain, a gene therapy, and more

Enjoy!

medium.com/the-spike/20...

30.12.2025 15:52 ๐Ÿ‘ 143 ๐Ÿ” 66 ๐Ÿ’ฌ 6 ๐Ÿ“Œ 11
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Rethinking the centrality of brain areas in understanding functional organization Nature Neuroscience - Parcellation of the cortex into functionally modular brain areas is foundational to neuroscience. Here, Hayden, Heilbronner and Yoo question the central status of brain areas...

New Perspective from myself, Sarah Heilbronner and @myoo.bsky.social . โ€œRethinking the centrality of brain areas in understanding functional organizationโ€ in Nature Neuroscience. ๐Ÿงต

rdcu.be/eVZ1A

23.12.2025 13:02 ๐Ÿ‘ 253 ๐Ÿ” 99 ๐Ÿ’ฌ 9 ๐Ÿ“Œ 10
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Not playing around: Why neuroscience needs toy models Amid the rise of billion-parameter models, I argue that toy models, with just a few neurons, remain essentialโ€”and may be all neuroscience needs.

Amid the rise of billion-parameter models, I argue that toy models, with just a few neurons, remain essentialโ€”and may be all neuroscience needs, writes @marcusghosh.bsky.social.

#neuroskyence

www.thetransmitter.org/theoretical-...

22.12.2025 14:44 ๐Ÿ‘ 61 ๐Ÿ” 26 ๐Ÿ’ฌ 4 ๐Ÿ“Œ 3

Our paper on data constrained RNN that generalize to optogenetic perturbations now citable on eLife:
doi.org/10.7554/eLif...

18.12.2025 23:07 ๐Ÿ‘ 42 ๐Ÿ” 18 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 2
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Young PI Symposium 2026 Visit the post for more.

๐Ÿ“ขAre you a young PI or senior postdoc in neuroscience looking to embark on the challenging journey of starting your own lab?

๐Ÿ“†Then save July 5, 2026 in your calendar and join us in Barcelona for the second Young PI Symposium.
youngpisymposium2026.com

13.12.2025 14:59 ๐Ÿ‘ 7 ๐Ÿ” 5 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 3
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Dimensionality reduction may be the wrong approach to understanding neural representations. Our new paper shows that across human visual cortex, dimensionality is unbounded and scales with dataset sizeโ€”we show this across nearly four orders of magnitude. journals.plos.org/ploscompbiol...

11.12.2025 15:32 ๐Ÿ‘ 224 ๐Ÿ” 64 ๐Ÿ’ฌ 7 ๐Ÿ“Œ 10
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Three types of remapping with linear decoders: A population-geometric perspective Author summary Place cells of the hippocampus form unique activity patterns in different environments, a process called remapping. However, it is not clear what the relationship is between changes in ...

Iโ€™m happy to share some recent work out in PLOS Computational Biology with @guille-martin.bsky.social and Christian Machens at @champalimaudr.bsky.social . We use neural coding and population geometry to study different perspectives on hippocampal remapping.

journals.plos.org/ploscompbiol...

09.12.2025 15:09 ๐Ÿ‘ 28 ๐Ÿ” 6 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 1

Thatโ€™s it, thanks for reading along. Thereโ€™s a lot more details in the paper about the framework and its relationship to the multitude of experimental and computational studies of hippocampal remapping. Please let us know what you think!

09.12.2025 15:09 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0

Overall, all three remapping mechanisms are likely to be accurate depictions of hippocampal activity changes under different conditions. More generally, this perspective is not limited to the hippocampus and can be used to understand neural variability in other brain areas as well!

09.12.2025 15:09 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
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In the paper, we simulate several examples of each remapping type in RNN models and quantify the types of neural activity patterns underlying them.

09.12.2025 15:09 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
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Null-space (NS) remapping features changes outside of the latent space, i.e., in the null space, and relates to changes in which neurons participate in a redundant code. This relates to more subtle activity changes due to excitability, trial-to-trial variability, and even cell birth and death.

09.12.2025 15:09 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
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Mixed-selective (MS) remapping explains activity modulation through changes or shifts in non-spatial, cognitive axes. This relates to ideas about mixed or conjunctive representations of position with other variables such as context, behavior, or sensory info.

09.12.2025 15:09 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
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Using this framework, we identify three underlying coding mechanisms that explain remapping.

Encoder-decoder (ED) remapping reflects a true change in the latent space, visualized as a rotation of the latent axes. This relates to classic multi-chart and grid realignment models, among others.

09.12.2025 15:09 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
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This allows us to visualize hippocampal population activity along positional and cognitive latent axes, with localized โ€œplace fieldsโ€ on top. From this perspective, neural trajectories are composed of a linear latent component, plus a nonlinear nullspace component.

09.12.2025 15:09 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

Many theories exist for remapping, but what types of neural activity patterns are compatible with these different views? We study this question in a model with one key assumption: that hippocampal population activity reflects a linearly-decodable latent space.

09.12.2025 15:09 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
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Three types of remapping with linear decoders: A population-geometric perspective Author summary Place cells of the hippocampus form unique activity patterns in different environments, a process called remapping. However, it is not clear what the relationship is between changes in ...

Iโ€™m happy to share some recent work out in PLOS Computational Biology with @guille-martin.bsky.social and Christian Machens at @champalimaudr.bsky.social . We use neural coding and population geometry to study different perspectives on hippocampal remapping.

journals.plos.org/ploscompbiol...

09.12.2025 15:09 ๐Ÿ‘ 28 ๐Ÿ” 6 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 1
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Are manifolds real?
Are latent circuits real?
Tatiana @engeltatiana.bsky.social uses one, infers the other, and says yes to both.

Also, how timescales are different and the same across the entire brain...

braininspired.co/podcast/226/

04.12.2025 18:52 ๐Ÿ‘ 38 ๐Ÿ” 11 ๐Ÿ’ฌ 2 ๐Ÿ“Œ 1
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Finally got the job adโ€”looking for 2 PhD students to start spring next year:

www.gao-unit.com/join-us/

If comp neuro, ML, and AI4Neuro is your thing, or you just nerd out over brain recordings, apply!

I'm at neurips. DM me here / on the conference app or email if you want to meet ๐Ÿ–๏ธ๐ŸŒฎ

03.12.2025 09:36 ๐Ÿ‘ 81 ๐Ÿ” 51 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 5