Marco Pompili

Intra-and Interhemispheric Signatures of Criticality at the Onset of Synchronization The cerebral cortex must flexibly alternate between locally segregated activity that supports specialization and long-range interactions that enable integration. How cortical networks balance these co...

I am more than pleased to share our new work with you:

"Intra- and Interhemispheric Signatures of Criticality at the Onset of Synchronization"

biorxiv.org/content/10.6...

Short 🧵 1/9:

New preprint out!
How does criticality propagate from local neuronal circuits to whole-brain dynamics?
We tackle this with a multiscale, connectome-based mouse model @ldallap.bsky.social . 🧵/n
👉 biorxiv.org/content/10.6...

Happy to announce the 2nd Hippocampus Green Meeting
📍 Barcelona, Spain
🗓️ May 11–12, 2026
Organized together with Manu Valero, Lisa Roux and Dan Bendor
🎤 Keynotes: Nachum Ulanovsky & György Buzsáki
‼️ Call for abstracts now open
🔗 hippocampusgreen.net/wp/
#HippocampusGreen

…and we have another work coming where we propose a way to study cell assemblies without binning or z-scoring. Stay tuned!

Detection of Cell Assemblies in High-Density Extracellular Electrophysiological Recordings Cell assemblies, i.e., concurrently active groups of neurons, likely underlie neural processing for higher brain functions. Recent technological progress has enabled large-scale recording of neuronal ...

Binning is necessary for the most common method of cell assembly detection that we also used in this study (ICA), but we agree this does have its limitations, which we discuss here: doi.org/10.1007/978-...

It remains unclear whether such co-firing truly matters for brain function. Here, we show that in the prefronto-amygdalar circuit, “cell assemblies” matter on timescales of up to ~40 ms: synchronous activity over longer windows fails to trigger a supralinear downstream response.

What cell assemblies are — and what they do for the brain — is a profound question and the central motivation behind this work! Most people define an assembly as a set of neurons that fire together (thereby enabling the plasticity associated with synchrony).

In sum: (1) this is, to our knowledge, the first experimental support for the “reader-centric” framework of cell assemblies; (2) assembly reading implements both pattern completion and pattern separation; and (3) assembly–reader relationships can be flexibly modified by learning. 10/10

Finally, we expected that assembly–reader relationships could flexibly change to reflect learning processes. Indeed, fear conditioning induced changes in AMY assembly → mPFC reader couplings, and conversely, changes in mPFC → AMY reading followed fear extinction. 9/10

The assembly–reader mechanism implements both pattern completion (responses did not simply increase proportionally with the number of active members) and pattern separation (responses were selective for specific assemblies and discriminated between overlapping assemblies). 8/10

Assembly activations exerted synergistic effects on reader neurons (not just a linear summation of responses to individual assembly members), and the identity of participating members mattered beyond their compound activity (spikes from neurons A and B > two spikes from A alone). 7/10

We recorded large neural ensembles from the medial prefrontal cortex (mPFC) and the amygdala (AMY), which are reciprocally interconnected, and showed that assembly activation could trigger firing responses in downstream neurons. 6/10

With rtodorova.bsky.social, Céline Boucly, Sidney Wiener, and Michaël Zugaro, we evaluated the downstream impact of cell assemblies: how is the co-activation of their members special? And how does the “reading” of this activity relate to brain computation and behavior? 5/10

György Buzsáki suggested that activation of a cell assembly may be meaningful only if it triggers specific responses in one or more target neurons, and proposed studying cell assemblies in terms of their impact on downstream “reader” neurons. doi.org/10.1016/j.ne... 4/10

Indeed, cell assemblies have been found to be involved in perception, memory, and executive and motor functions. Nevertheless, it is still unknown whether such “representations” in specific neuronal populations are relevant for the rest of the brain. 3/10

Groups of neurons firing together have been proposed to constitute a computational unit of the brain since Donald Hebb’s theory (1949). Today, the notion of a cell assembly is used to designate a group of cells involved in an action or representing a percept or concept. 2/10

Adaptive communication between cell assemblies and “reader” neurons shapes flexible brain dynamics Cell assemblies have been proposed as key units of brain activity, underlying diverse functions, but their basic features are not well understood. This study shows that interactions between cell assem...

Cell assemblies are drawing increasing attention in neuroscience, but one could argue that they are just an epiphenomenon. Is the activity of cell assemblies relevant for the brain?
The short answer is yes. The long answer is in our paper, now online at PLOS Biology. 🧵👇 1/10
doi.org/10.1371/jour...

Joint modelling of brain and behaviour dynamics with artificial intelligence - Nature Reviews Neuroscience Artificial intelligence is rapidly advancing our mechanistic understanding of the shared structure between the brain and higher-order behaviours. In this Review, Mathis and Mathis synthesize state-of-...

Joint modelling of brain and behaviour dynamics with artificial intelligence

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

🧠📢 New preprint alert

Large-scale ephys is exploding but spike sorting remains the computational bottleneck. A 2-hr, 6-probe Neuropixels 2.0 Quad Base session can take over a week to sort on a single machine. Here's a better solution. 🧵

#neuroskyence #compneurosky

💡 Why it matters: understanding how context fear is regulated after extinction helps explain the limits of extinction-based therapies.

🙏 Thanks to all the authors — in particular Bill Godsil who set up the whole project and Adam Eckmier who made most of the experimental work. 🧵 5/5

📊 Stimulating vHPC→mPFC projections during context exposure after cued extinction we
• Observed decreased contextual fear
• Found no effects on motricity or contextual fear immediately after conditioning

➡️ Thus, vHPC–PL projections also modulate contextual fear expression after extinction. 🧵 4/5

Previous work showed vHPC→prelimbic (PL) activity regulates cue-related fear after extinction.
But whether this pathway also controls contextual fear was unknown.
So we tested it directly 👇 🧵 3/5

📄 “Ventral hippocampus modulates prefrontal control of background contextual fear after cued extinction”

We looked at how the ventral hippocampus (vHPC) shapes prefrontal regulation of contextual fear after extinction. 🧵 2/5

Let’s use a good occasion to break my Bluesky shyness 😅 — a new article just came out!
This one goes back to data from the very start of my PhD, and I’m so happy to see it finally published 🧠

👉 onlinelibrary.wiley.com/doi/full/10.... 🧵1/5