Desdemona Fricker

Grid cells accurately track movement during path integration-based navigation despite switching reference frames - Nature Neuroscience Grid cells do not maintain a stable pattern during a self-motion-based task, but track animal movement in multiple local reference frames and reanchor to task-relevant objects, thus estimating local r...

No GPS in the head? Path integration by entorhinal grid cells without the grid pattern. Interesting paper from Heidelberg. www.nature.com/articles/s41...

YouTube video by Weizmann Institute of Science Bat Island: The New Era of Science

Neuroscience projects last several years, and you are usually a bit jaded by the time you wrap it up. Not this one– spending several months on an island in the middle of nowhere, away from all the craziness of the world reminds you how beautiful the world really is.

www.youtube.com/watch?v=46sv...

The postsubiculum as a head-direction cortex The organisation of thalamocortical networks follows a conserved structure. Traditionally, these are divided into primary sensory systems that receive…

Really excited to share this Opinion piece we've been working on with fellow head-direction cell geeks @apeyrache.bsky.social @desdemonafricker.bsky.social and (bsky-less?) Andrea Burgalossi! While head-direction cells pop up in many cortical regions, we think that one of them is quite unique (1/8)

🚨new paper: the head-direction circuit as a model of primary thalamocortical system. Check this out 👇

kudos to @adrian-du.bsky.social for the huge amount of work put into this opinion piece, starting with the beautiful figures comparing the different thalamocortical systems 🤩

Thanks to the Capitainerie de l’Isle and to Nathalie for hosting our exhibit ✨

Travel awards are available for undergraduate students looking to attend #Cosyne25! The application is short, and the deadline is Nov 12. @cosynemeeting.bsky.social

Application: shorturl.at/6NEyk

More info: www.cosyne.org/travel-grants

(1/2)

Dear #ParisNeuroscience community, here is the schedule of the upcoming 'Neural Networking Night' season !

2/6

Recording in decision-making regions from many neurons at once revealed the neurons' collective evolution as decisions were made

Each decision had two phases: first, neural state was sensitive to sensory inputs; then, trajectories in neural state space turned and became insensitive to inputs.

Thanks to the Capitainerie de l’Isle and to Nathalie for hosting our exhibit ✨

Transitions in dynamical regime and neural mode during perceptual decisions - Nature Simultaneous recordings were made of hundreds of neurons in the rat frontal cortex and striatum, showing that decision commitment involves a rapid, coordinated transition in dynamical regime and neura...

How does the brain decide? 🧠

Our new @nature.com paper shows that neural activity switches from an 'evidence gathering' to a 'commitment' state at a precise moment we call nTc.

After nTc, new evidence is ignored, revealing a neural marker for the instant when the mind is made up.

rdcu.be/eGUrv

Coherent dynamics of thalamic head-direction neurons irrespective of input While the thalamus is known to relay and modulate sensory signals to the cortex, whether it also participates in active computation and intrinsic signal generation remains unresolved. The anterodorsal...

🚨New preprint alert!

The thalamus has long been seen as a relay of sensory signals to cortex.
But could it also generate its own structured activity?
Our study explores this question in the head-direction (HD) system.

Some explanation 🧵👇 1/13

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

Voir Montrer Regarder 👀
Observer Mesurer Vérifier #SciArt
If you are in Paris in September check out our exhibit “Regards Croisés”: Come for the Art, stay for the Science ! This scientific outreach event is supported by @c-brains.bsky.social, @sppin-cnrs.bsky.social and the Capitainerie de l’Isle.

Granularity of thalamic head direction cells Head direction signaling is fundamental for spatial orientation and navigation. The anterodorsal nucleus of the thalamus (ADn) contains a high density of head direction (HD) cells that process sensori...

*New preprint from the lab* – “Granularity of thalamic head direction cells”
doi.org/10.1101/2025...
🧠📈 🧪
1/11

Color-coded mean firing rate maps of place fields detected in the forth trials (left, sorted by the location of place fields peak) and back trials (right, sorted according to firing order in the forth trials) of all bidirectional cells recorded in the track with objects (top) or without objects (bottom). The color represents the intensity of the mean firing rate in a given bin normalized to the maximum mean firing rate (peak rate) in each direction. Note that in the CP condition, the mean firing map in one direction is the mirror image of the mean firing map in the other direction, indicating strong distance coding.

Happy to share our new paper with Mathilde Nordlund and Julie Koenig out @currentbiology.bsky.social. We used virtual reality in mice to study hippocampal distance coding. Our results suggest a primary contribution of grid cells to distance over cue-dependent place cell coding.
shorturl.at/63yFo

Thrilled to share that our work is now published in Science! ✨

We found a preference for visual objects in the mouse spatial navigation system where they dynamically refine head-direction coding. In short, objects boost our inner compass! 🧭

www.science.org/doi/10.1126/...

🧵1/

Cooperative actions of interneuron families support the hippocampal spatial code Identifying the computational roles of different neuron families is crucial for understanding neural networks. Most neural diversity is embodied in various types of γ-aminobutyric acid–mediated (GABAe...

And the Valero / Buzsaki paper: www.science.org/doi/10.1126/...

Two flagship papers from the International Brain Laboratory, now out in ‪@Nature.com‬:
🧠 Brain-wide map of neural activity during complex behaviour: doi.org/10.1038/s41586-025-09235-0
🧠 Brain-wide representations of prior information in mouse decision-making: doi.org/10.1038/s41586-025-09226-1 +

Task engagement differentially drives hippocampal and neocortical neural codes Sensory inputs are progressively transformed into internal representations of the environment along the cortical hierarchy. How does the behavioral relevance of these inputs affect this encoding? Usin...

The main project from my PhD, in collaboration with Manuela Allegra and @schlab.bsky.social is now available as a preprint! We wondered how the hippocampus and the visual cortex may differ in the way they refine sensory inputs into internal representations

🎨🔬 Quand l’art rencontre la science !

Le SPPIN est heureux de vous annoncer l'Expo #SciArt “Regards Croisés” avec l’artiste Sophie Sainte-Marie-Heim et notre collègue @desdemonafricker.bsky.social

🗓 22–28 sept. 2025
📍 Capitainerie de l’Isle, 26 rue Chanoinesse, Paris 4e

Venez nombreux !

🚨PhD student position in #cognitive_psychology and #neuroscience, on a project directed by André Knops and in collaboration with the Dugué Lab!

@upcite.bsky.social | @cnrs.fr

Funded by the @agencerecherche.bsky.social (Agence nationale de la recherche)

www.linkedin.com/jobs/view/42...

📣 We are expanding! Repost 🙏🏽

- Postdoc (funded by @simonsfoundation.org grant on synchronisation between cognitive representations and stepping)
- Project Associates
- Create your role! (Reach out if you are keen on these topics and these roles do not define you 👀🤗)

www.neuroact.in

Remote activation of place codes by gaze in a highly visual animal - Nature Place cells in the chickadee hippocampus coherently represent locations in space, whether physically visited or viewed, enabling spatial reasoning at a distance through a unified process coordinated b...

Remote activation of place codes by gaze in a highly visual animal www.nature.com/articles/s41... - very cool study with chickadees!

Thanks to Michael Graupner and the fabulous Orientation and Coordination team 🤩 for sharing the excitement 🥳 and for sharing the Science 🧠

Voir Montrer Regarder 👀
Observer Mesurer Vérifier #SciArt
If you are in Paris in September check out our exhibit “Regards Croisés”: Come for the Art, stay for the Science ! This scientific outreach event is supported by @c-brains.bsky.social, @sppin-cnrs.bsky.social and the Capitainerie de l’Isle.

Sensory responses of visual cortical neurons are not prediction errors Predictive coding is theorized to be a ubiquitous cortical process to explain sensory responses. It asserts that the brain continuously predicts sensory information and imposes those predictions on lo...

1/3) This may be a very important paper, it suggests that there are no prediction error encoding neurons in sensory areas of cortex:

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

I personally am a big fan of the idea that cortical regions (allo and neo) are doing sequence prediction.

But...

🧠📈 🧪

Synaptic plasticity of prefrontal long-range inhibition regulates cognitive flexibility While glutamatergic synaptic plasticity is believed to be a fundamental mechanism mediating learning, the behavioral significance of plasticity at cortical GABAergic synapses remains less well underst...

New work! Learning is assumed to involve synaptic plasticity, but which specific synapses change to enable higher order cognitive functions? We actually find that cognitive flexibility involves potentiation of long-range GABAergic synapses from prefrontal PV neurons: www.biorxiv.org/content/10.1...

Great wave of @agencerecherche.bsky.social results for SPPIN ! Congrats to our researchers & their amazing partners!

@desdemonafricker.bsky.social : HDNavigGO
@npanayotis.bsky.social : ReGeNeRETT
G. Caron: MNIONALS (JCJC)
@brandonstell.bsky.social : AdaptingMovement

@cnrs.fr @upcite.bsky.social

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...

Our new paper out now in Science explores how neural activity in the lateral entorhinal cortex (LEC) *drifts* over time - and *jumps* at key boundaries - to help organize events in memory.

🔗 www.science.org/doi/10.1126/...

Here's a quick summary of what we found 🧵👇

Event structure sculpts neural population dynamics in the lateral entorhinal cortex Our experience of the world is a continuous stream of events that must be segmented and organized at multiple timescales. The neural mechanisms underlying this process remain unknown. In this work, we...

Your brain doesn’t just passively track time ⏳ - it structures it.
In @Science.org we show that activity in 🧠 memory circuits (LEC) drifts constantly, but makes sharp jumps at key moments, segmenting life into meaningful events. (1/2)

👉 www.science.org/doi/10.1126/...