Toviah Moldwin

Toviah Moldwin

@tmoldwin.bsky.social

Computational neuroscience: Plasticity, learning, connectomics.

312 followers346 following344 posts

Toviah Moldwin reposted

Toviah Moldwin reposted

On today’s science headlines : A newly discovered species of carnivorous caterpillar on the Hawaiian island of Oahu has earned the nickname “bone collector” for its eerie habit of adorning itself with the remains of its prey, such as ant heads and fly wings. 🪲 🧪

Toviah Moldwin reposted

Toviah Moldwin reposted

High-Dimensional Dynamics in Low-Dimensional Networks. New preprint with a former undergrad, Yue Wan. I'm not totally sure how to talk about these results. They're counterintuitive on the surface, seem somewhat obvious in hindsight, but then there's more to them when you dig deeper.

Adventures in proofreading: Journal has online system to edit proofs. Work for an hour, am auto-logged out. Log back in, all edits are gone. Try editing on PDF instead. For a substantial number of edits, it's impossible to highlight the relevant text because UNCORRECTED PROOF gets in the way.

Now out in PLOS CB! We propose a simple, perceptron-like neuron model, the calcitron, that has four sources of [Ca2+]...We demonstrate that by modulating the plasticity thresholds and calcium influx from each calcium source, we can reproduce a wide range of learning and plasticity protocols.

journals.plos.orgThe calcitron: A simple neuron model that implements many learning rules via the calcium control hypothesisAuthor summary Researchers have developed various learning rules for artificial neural networks, but it is unclear how these rules relate to the brain’s natural processes. This study focuses on the ca...

Toviah Moldwin reposted

Sharing our most recent paper, in which we find that electrical synapses in C. elegans drive action selection by "filtering" sensory information. C. elegans can learn temp, move across the temp. gradient and then track that temp. How? Configuration electrical synapses www.cell.com/cell/fulltex... 1/

cell.comConfiguration of electrical synapses filters sensory information to drive behavioral choicesSensory information can be differentially processed, enabling similar sensory stimuli to elicit different, context-specific behavioral strategies. This study uncovers a conserved configuration of elec...

Toviah Moldwin reposted

More people should leave academia to start companies. There's a lot of overlap in the skill sets. If you can turn an idea into a published paper, there's a decent chance you can also turn an idea into a product. Probably more impactful in the long run than writing papers that 5 people will read.

Toviah Moldwin reposted

Ever wondered what different layer-5 PC types do for learning? Our work suggests that one (IT PCs) does representational learning whereas the other (ET PCs) encodes representational value! A great exp-theory collaboration with the Larkum and Takahashi's labs!

bioRxiv Neuroscience@biorxiv-neursci.bsky.social

Distinct roles of cortical layer 5 subtypes in associative learning https://www.biorxiv.org/content/10.1101/2025.01.07.631500v1

Long shot, but does anyone have a version of the Allen Microns connectomics dataset with *all* synapses labeled as E or I (based on synapse morphology, not presynaptic neuron identity?)

Toviah Moldwin reposted

Excited to see @thetransmitter.bsky.social feature our preprint on how the neural code changes across the cortical hierarchy! A multi-region perspective on categorical selectivity 🧱 and geometric dimensionality 📐 Blueprint thread coming soon— after I am done with panettone digestion 🥮!

thetransmitter.orgMost neurons in mouse cortex defy functional categoriesThe majority of cells in the cerebral cortex are unspecialized, according to an unpublished analysis—and scientists need to take care in naming neurons, the researchers warn.

Toviah Moldwin reposted

Key-value memory is an important concept in modern machine learning (e.g., transformers). Ila Fiete, Kazuki Irie, and I have written a paper showing how key-value memory provides a way of thinking about memory organization in the brain: arxiv.org/abs/2501.02950

arxiv.orgKey-value memory in the brainClassical models of memory in psychology and neuroscience rely on similarity-based retrieval of stored patterns, where similarity is a function of retrieval cues and the stored patterns. While parsimo...

Toviah Moldwin reposted

Toviah Moldwin reposted

DAY 22: Advent of Comp Neuro 🎄🤖🧠🧪 Memories in a network can drift at the single neuron level, but persist at the population level! 🍎🍏 “Drifting assemblies for persistent memory: Neuron transitions and unsupervised compensation” www.pnas.org/doi/full/10....

Aitor Morales-Gregorio@aitormg.bsky.social

DAY 21: Advent of Comp Neuro 🎄🤖🧠🧪 Aligning stimuli to spontaneous activity creates more robust responses, both in a model and in ferrets! “The nature-nurture transform underlying the emergence of reliable cortical representations” By @traegenap.bsky.social et al www.biorxiv.org/content/10.1...

People climb the career ladder to get a management position (PI) and then once they get there they find that they have less time for non management-related things <surprised Pikachu face>.

Toviah Moldwin reposted

Neuronal dynamics can be #balanced without the need of strong external currents, as usually done, here with A. Politi we explain how (open access article 2024) #complexity #neuroscience #neuroskyence #compneurosky pubs.aip.org/aip/cha/arti...

pubs.aip.orgA robust balancing mechanism for spiking neural networksDynamical balance of excitation and inhibition is usually invoked to explain the irregular low firing activity observed in the cortex. We propose a robust nonli

Toviah Moldwin reposted

DAY 15: Advent of Comp Neuro 🎄🤖🧠🧪 Heterogeneity of neural properties can improve some computational functions, but homogeneity also has its advantages! It's complicated 😅 “Neural heterogeneity controls computations in spiking neural networks” @rgast.bsky.social et al www.pnas.org/doi/epub/10....

Aitor Morales-Gregorio@aitormg.bsky.social

DAY 14: Advent of Comp Neuro 🎄🤖🧠🧪 Neurotransmitter expression is very different throughout the cortex, and those differences are aligned with the hierarchy! “Gradients of neurotransmitter receptor expression in the macaque cortex” By @seanfw.bsky.social et al www.nature.com/articles/s41...

Toviah Moldwin reposted

1/ Okay, one thing that has been revealed to me from the replies to this is that many people don't know (or refuse to recognize) the following fact: The unts in ANN are actually not a terrible approximation of how real neurons work! A tiny 🧵. 🧠📈 #NeuroAI #MLSky

Blake Richards@tyrellturing.bsky.social

Why does anyone have any issue with this? I've seen people suggesting it's problematic, that neuroscientists won't like it, and so on. But, I literally don't see why this is problematic...

Toviah Moldwin reposted

Toviah Moldwin reposted

Check out our new preprint! We show there is a better learning algorithm for #compneuro than gradient descent (GD): exponentiated gradients (EG). tl;dr: EG respects Dale's law, produces weight distributions that match biology, and outperforms GD in biologically relevant scenarios. 🧠📈 🧪

Jonathan Cornford@repromancer.bsky.social

Why does #compneuro need new learning methods? ANN models are usually trained with Gradient Descent (GD), which violates biological realities like Dale’s law and log-normal weights. Here we describe a superior learning algorithm for comp neuro: Exponentiated Gradients (EG)! 1/12 #neuroscience 🧪

Thing I've noticed when I use AI to code (Cursor with Claude) - there is a very pronounced 80/20 effect, where the AI is very good at reducing the work needed to get 80% of the job done - the basic architecture, the boilerplate, but is much worse at the final 20% - cosmetics, QA, etc.

Toviah Moldwin reposted

DAY 9: Advent of Comp Neuro 🎄🤖🧠🧪 The shape and speed of neural trajectories, as wells as manifold orientation are shaped by the network structure and inputs, which we can control! 💫 "Dynamic control of neural manifolds" www.biorxiv.org/content/10.1...

Aitor Morales-Gregorio@aitormg.bsky.social

DAY 8: Advent of Comp Neuro 🎄🤖🧠🧪 Zebrafish grown under anesthesia, with no neural activity, are immediately able to swin and respond to visual stimuli 🤯🐟 "Functional neuronal circuits emerge in the absence of developmental activity" www.nature.com/articles/s41...

Toviah Moldwin reposted

Toviah Moldwin reposted

DAY 5: Advent of Comp Neuro 🎄🤖🧠🧪 Heavy-tailed distributions enable smooth transitions to chaos and other biologically realistic activity. “Edge of Chaos and Avalanches in Neural Networks with Heavy-Tailed Synaptic Weight Distribution” journals.aps.org/prl/abstract...

Aitor Morales-Gregorio@aitormg.bsky.social

DAY 4: Advent of Comp Neuro 🎄🤖🧠🧪 Travelling waves seem to be everywhere in the brain. Detecting them is now easy and reproducible with Cobrawap! 🤠🐍 "A modular and adaptable analysis pipeline to compare slow cerebral rhythms across heterogeneous datasets" www.cell.com/cell-reports...

Why are journals so adamant about not accepting revised manuscripts with trackchanges? There's literally one button you press to show/hide the revisions, it's clearly the easiest way for reviewers to see what revisions you've made. Not allowing it is the exact opposite of what makes sense.