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Abraham Zelalem Vollan

@azvollan.bsky.social
360 followers 266 following 37 posts

Systems neuroscientist, MD/PhD. Postdoc in Rune Enger’s lab @UiO, PhD from Moser lab @kavlintnu.bsky.social. Population dynamics, sleep, high-density ephys.

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Reposted by Abraham Zelalem Vollan
Zilong Ji @zilong-ji.bsky.social · 03/10/2026
Excited that our paper, “The limbic navigation system as a hierarchical RNN”, has been accepted at #NeurIPS! Joint work with two talented students, Huiwen Zhang, Krishna Gorantla, and @neilburgess10.bsky.social. We use a multi-module RNN to explore how the brain’s navigation circuits works.
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Eric Denovellis @eric-denovellis.bsky.social · 02/10/2026
I wanted to highlight the work of Alison Comrie et al. that recently came out in Neuron and I don’t think it is getting enough attention: paper: cell.com/neuron/fulltext/S0896-6273(26)00674-4 #neuroskyence
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Adrian Duszkiewicz @adrian-du.bsky.social · 26/09/2026
Interesting new study from the Frank lab: Hippocampal representations of alternative possibilities are flexibly generated to meet cognitive demands
cell.com
Hippocampal representations of alternative possibilities are flexibly generated to meet cognitive demands
Comrie et al. show that the hippocampus flexibly represents different alternative possibilities—including paths ahead, behind, and far away—to meet distinct cognitive demands related to decision-makin...
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Reposted by Abraham Zelalem Vollan
Andrej Bicanski @andrejbicanski.bsky.social · 22/09/2026
Now accepted and published --- with many thanks to the referees for helping sharpen the manuscript. Long time since the first notes. Good to see it officially out. www.cell.com/current-biol...
cell.com
A vector navigation and inference architecture can construct universal cognitive maps for abstract reasoning
Bicanski proposes an algorithm and neural mechanisms for the iterative construction of abstract cognitive maps via non-local inference. Map positions are triangulated and memorized by a set of extant ...
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Reposted by Abraham Zelalem Vollan
Masahiro Nakano @masahironakano.bsky.social · 19/09/2026
My first paper has been published in Hippocampus! bsky.app/profile/masa... Thank you Caswell and Claudia for your support!
bsky.app
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Reposted by Abraham Zelalem Vollan
The Transmitter @thetransmitter.bsky.social · 06/08/2026
For 30 years, neuroscientists have argued about whether theta sweeps are just passive sensing, or something closer to planning. So which is it? #neuroskyence By @natmesanash.bsky.social www.thetransmitter.org/memory/new-f...
thetransmitter.org
New findings begin to resolve theta sweep debate
Theta sweeps have been mired in controversy for decades, but the emerging consensus view suggests that they function in attention and goal direction.
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Reposted by Abraham Zelalem Vollan
Edvard I Moser @edvardmoser.bsky.social · 06/08/2026
Out now in @science.org : How does the brain rapidly scan space to guide navigation? We found that the brain’s internal map is continuously retuned from moment to moment, focusing neural activity on what matters most. 🧵1/8 👉 www.science.org/doi/10.1126/...
science.org
Adaptive modulation of theta sweeps in the brain’s navigation circuit
Efficient navigation requires prioritizing information from behaviorally relevant locations. In rats, such selective sampling may arise from theta-paced sweeps in grid and place cell populations, whic...
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Abraham Zelalem Vollan @azvollan.bsky.social · 06/08/2026
Now in Science: How does the brain’s navigation system allocate its limited representational resources during behavior? We found that grid cells sweep toward locations of interest, providing a potential mechanism for allocating spatial attention in the cognitive map.🧵 science.org/doi/10.1126/...
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Anna Gruzdeva @annagru.bsky.social · 04/08/2026
Happy to share our preprint! We show that hypothalamic hunger-promoting AgRP neurons reflect proximity to food across different mazes in hungry mice. After mice discover food, AgRP activity decreases as they approach the food and increases as they move away.
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Oscar Chadney @oscar-chadney.bsky.social · 09/07/2026
I’m excited to share our latest preprint, and the main work from my PhD, on the role of the direct entorhinal input in hippocampus CA1 spatial coding. 1/9
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Neil Burgess @neilburgess10.bsky.social · 01/07/2026
Ever wondered how the hippocampal cognitive map is read-out? @changmin-yu.bsky.social @zilong-ji.bsky.social with Jake & John, show that, during navigation, theta sweeps indicate remembered goal-directions (cf. current/next movements or perceptual targets) 1/2 www.nature.com/articles/s41...
Decoded locations from place cell firing sweep towards a remembered goal location during each theta cycle irrespective of the current movement or head direction
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Reposted by Abraham Zelalem Vollan
Jo Carpenter @jocarpenter.bsky.social · 07/07/2026
The Moser Group is presenting our work on Wednesday afternoon at #FENS2026! •Mechanism for L-R sweeps •Attention modulation of sweeps •Grid/place remapping rules & dynamics •”Mega torus” as a hi-capacity memory space •Moving the grid bump •Development of tori & rings •RSC/HC pops. in a spatial task
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AntonioFR @antferrui.bsky.social · 06/07/2026
Our work on goal-directed theta sweeps is out! We found two different types of theta sweeps in the rat hippocampus. During random foraging, left-right alternating sweeps dominated (Vollan, 25). However, during memory-guided navigation sweeps pointing to hidden goal locations emerged with learning.
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Kris Jensen @kristorpjensen.bsky.social · 11/06/2026
It has been super fun to work on this, where we learned that: 1) Mouse PFC is needed for model-based override of habits. 2) Separate PFC populations encode a 'policy' and the current 'value'. 3) The policy and value codes alternate theta sweeps towards the goal. ...and much much more!
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shijiegu @shijiegu.bsky.social · 03/06/2026
Last week, we finally submitted my first paper during my PhD (bioRXiv: www.biorxiv.org/content/10.6...). The paper is about change-of-mind (COM) behavior. You know when you're taking a test and switch your answer after second-guessing yourself? We studied what happens in the brain at that moment.
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Reposted by Abraham Zelalem Vollan
Brad Hulse @bradkhulse.bsky.social · 21/05/2026
Story time friends... Ring attractor networks rely on fine-tuned symmetric connectivity. The fly head direction network has ring attractor dynamics but heterogeneous connectivity. How is this possible? 1/🧵 Link: www.biorxiv.org/content/10.6...
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andy alexander @andyalexander.bsky.social · 28/04/2026
Very excited to announce the first preprint from the lab @ucsantabarbara.bsky.social -- "Predictive pursuit emerges in high-dimensional RNNs." @wtredman.bsky.social (starting his own group at JHU this fall) summarizes the work nicely in this thread.
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Emily A. Aery Jones @emilyaeryjones.bsky.social · 01/04/2026
My main postdoc work is now published: www.nature.com/articles/s41...! We (myself, Isabel Low, Frances Cho, and @lgiocomo.bsky.social) discovered task-relevant remote representations in entorhinal cortex independent of CA1. #paperthread below! 1/13
nature.com
Entorhinal cortex represents task-relevant remote locations independently of CA1 - Nature Neuroscience
Neurons in medial entorhinal cortex collectively represent discrete nonlocal positions during immobility. During this nonlocal coding, CA1 is uncoupled from entorhinal cortex. These representations ar...
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Abraham Zelalem Vollan @azvollan.bsky.social · 11/03/2026
Brilliant work on the development of grid cells by Matteo et al!
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Reposted by Abraham Zelalem Vollan
Andrej Bicanski @andrejbicanski.bsky.social · 09/03/2026
1/N: Dear cognitive map fans, I’d like to share a model I’ve been working on for a while (clearing backlog :). I show how a vector navigation architecture (VNA) and a “positional inference network” (PIN) can build Universal Cognitive Maps (UCMs) for abstract spaces. www.biorxiv.org/content/10.6...
biorxiv.org
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Abraham Zelalem Vollan @azvollan.bsky.social · 27/02/2026
Fantastic opportunity to do pioneering single-unit recordings from the HUMAN hippocampus and other parts of the brain, with @jorgen-sugar.bsky.social at @uio.no, Norway.
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Reposted by Abraham Zelalem Vollan
torsteinslettmoen.bsky.social @torsteinslettmoen.bsky.social · 20/02/2026
1/6 Do neighboring #PlaceCells in #Hippocampus CA1 map neighboring locations in space? 🧠🗺️ Is there micro-scale spatial topography in the hippocampus? See our latest paper from @kavlintnu now out in @pnas.org www.pnas.org/doi/10.1073/...
pnas.org
Place cells in CA1 lack topographical organization of firing locations | PNAS
Topography is a well-described and well-known concept for cortical organization in primary sensory and motor cortices of mammalian brains. Similar ...
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Lucie Descamps @ldescamps.bsky.social · 10/02/2026
My first first-author paper is on bioRxiv! Here we ask whether the same subset of neurons in ACC always display object correlates during extensive familiarisation to 2 objects. A short 🧵1/10
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Ben Kanter @beneuroscience.bsky.social · 13/02/2026
Happy belated publication of some of my PhD work! Building on our findings that grid field firing rate changes can cause hippocampal remapping and memory impairment, here we show that this effect has a fixed input-output relationship, and we can even predict how place cells will remap!
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koenvervaeke.bsky.social @koenvervaeke.bsky.social · 13/02/2026
We are #hiring 2 PhD students at the University of Oslo! 🇳🇴 1️⃣ Systems Neuro: Spatial memory & addiction 2️⃣ Neuro/Cancer: Glioblastoma invasion. Details: vervaeke-lab.org/Hiring Please RT! 🔄 @UiO_LifeSci #Neuroscience #PhD #SystemsNeuro #Glioblastoma
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Portugues Lab @portugueslab.bsky.social · 08/02/2026
Have you ever wondered how the brain should represent the sensory world in order to generate behavior? Read our new preprint: work by Shuhong Huang shuhonghuang.bsky.social with our long-standing collaborator James Fitzgerald at Northwestern.
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Adrien Peyrache @apeyrache.bsky.social · 11/02/2026
New paper alert! 🚨 We found that the brain's compass is remarkably stable at two scales 1️⃣ the system maintains its internal organization for weeks 2️⃣ It "remembers" its orientation for weeks, even after a single visit This may be key to how the brain aligns its other maps. Paper: rdcu.be/e3waP
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Ben Kanter @beneuroscience.bsky.social · 31/01/2026
Check out our commentary on a recent paper arguing that neural activity in the (lateral) entorhinal cortex intrinsically drifts over a month-long period in humans. With @virginievanw.bsky.social @vigano.bsky.social and Raphaël Bordas. www.eneuro.org/content/13/1...
eneuro.org
A Passage of Time Signal in the Human Brain
In a dense-sampling resting–state functional magnetic resonance imaging study, Wang et al. (2025) recorded two individuals’ functional connectivity patterns over 30 consecutive days to find a marker o...
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Abraham Zelalem Vollan @azvollan.bsky.social · 28/01/2026
We had a lot of fun doing these experiments! Theta sweeps in MEC and internal direction signals in parasubiculum track moving objects during pursuit and reverse during backward movement. Simultaneously recorded HD cells in other areas remain locked to head direction across behaviors:
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Abraham Zelalem Vollan @azvollan.bsky.social · 25/01/2026
Such an elegant study, congratulations to all of you!
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Masahiro Nakano @masahironakano.bsky.social · 16/01/2026
I’m excited to share my first PhD preprint!🎉 We studied how interactions between medial entorhinal cortex (MEC) and hippocampus shape theta sequences during navigation, and asked whether some “planning-like” patterns in hippocampus could arise from upstream MEC dynamics. (1/8)
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clykken.bsky.social @clykken.bsky.social · 25/09/2025
1/8 How can the brain create countless unique memories using a single, universal metric of space? We’ve been waiting for the answer to this for two decades! Read it here: www.biorxiv.org/content/10.1...
biorxiv.org
Functional independence of entorhinal grid cell modules enables remapping in hippocampal place cells
A systems-level understanding of cortical computation requires insight into how neural codes are transformed across distinct brain circuits. In the mammalian cortex, one of the few systems where such ...
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Abhilasha Joshi, PhD @rhythmicspikes.bsky.social · 17/09/2025
1/ 🚨 New preprint! 🚨 Excited and proud (& a little nervous 😅) to share our latest work on the importance of #theta-timescale spiking during #locomotion in #learning. If you care about how organisms learn, buckle up. 🧵👇 📄 www.biorxiv.org/content/10.1... 💻 code + data 🔗 below 🤩 #neuroskyence
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Matteo Guardamagna @matteoguardamagna.bsky.social · 12/07/2025
Our collaboration - from PhD work - examining input-specific (EC L3) contributions to rate and temporal coding in CA1 place cells is now out in @natcomms.nature.com 🔬🧠 rdcu.be/evWtz
rdcu.be
Direct entorhinal control of CA1 temporal coding
Nature Communications - Temporal coding in the hippocampus is thought to be key for memory and predictions. Here, the authors show that blocking one entorhinal input affects two aspects of...
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Angelo Forli @aforli89.bsky.social · 09/07/2025
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...
nature.com
Replay and representation dynamics in the hippocampus of freely flying bats - Nature
Nature - Replay and representation dynamics in the hippocampus of freely flying bats
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Rajat Saxena @rajatsxn.bsky.social · 30/06/2025
Our work with Maxim Bazhenov's group showing interleaved replay of new and old memories within individual Up states using a combination of biophysical modeling and electrophysiology experiments.
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Edvard I Moser @edvardmoser.bsky.social · 26/06/2025
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/...
science.org
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...
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Ben Kanter @beneuroscience.bsky.social · 26/06/2025
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 🧵👇
science.org
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...
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Reposted by Abraham Zelalem Vollan
Nathalie Krauth @nkrauth.bsky.social · 28/05/2025
Honored to share that our paper is out today in Nature Neuroscience: www.nature.com/articles/s41... We identify a hypothalamic-brainstem circuit linking internal states to locomotion: These projections drive safety-focused movement over competing behavior. #Neuroscience #Hypothalamus #Locomotion
nature.com
A hypothalamus–brainstem circuit governs the prioritization of safety over essential needs - Nature Neuroscience
Animals need to adapt behavior to balance survival with fulfillment of essential needs. Krauth et al. identify neurons in the lateral hypothalamus that, when activated, prioritize survival over other ...
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Antonio Falasconi @antofala.bsky.social · 28/05/2025
Forelimb movement control at the basal ganglia - brainstem interface! Happy to finally share this work from me and @harsh-kanodia.bsky.social with Silvia Arber! @biozentrum.unibas.ch @fmiscience.bsky.social www.nature.com/articles/s41...
nature.com
Dynamic basal ganglia output signals license and suppress forelimb movements - Nature
Basal ganglia output neurons fire dynamically in bidirectional and movement-specific patterns to license forelimb movements. 
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Portugues Lab @portugueslab.bsky.social · 23/05/2025
Are you interested in visual systems? How are they similar or different across species? Read the review by Ryosuke @ryosuketanaka.bsky.social and Ruben published today in @natrevneuro.nature.com. It is available here: rdcu.be/enlpC
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Ben Kanter @beneuroscience.bsky.social · 26/04/2025
As I transition over to Bluesky I have to plug our new #book. If you haven't already, check out the 2nd edition of The #Hippocampus Book! academic.oup.com/book/59509?s...
academic.oup.com
The Hippocampus Book
Abstract. The Hippocampus Book investigates the structure, function and pathology of the hippocampus and related cortical areas. It highlights the importan
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Kadjita Asumbisa @kasumbisa.bsky.social · 15/04/2025
Excited to share the sequel to our 2022 paper! In this follow-up, we show that the stable head direction (HD) signals we reported in blind mice rely on stereo olfaction—that is, the comparison of odor info. between the two nostrils. Link: www.nature.com/articles/s41... 🧵highlights below
nature.com
Stereo olfaction underlies stable coding of head direction in blind mice - Nature Communications
Stereo olfaction involves comparing odor differences between the two nostrils. Here, using neuronal recordings and a behavioral test, the authors demonstrate that blind mice use stereo olfaction to fo...
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Michael Reiser @michaelreiser.bsky.social · 27/03/2025
I know there's a 𝒍𝒐𝒕 going on right now, but I couldn’t be prouder to share this long-incubated labor of love: the complete connectome of the male 𝐷𝑟𝑜𝑠𝑜𝑝ℎ𝑖𝑙𝑎 optic lobe 🧠🪰 🔗 www.nature.com/articles/s41...
nature.com
Connectome-driven neural inventory of a complete visual system - Nature
A connectome of the right optic lobe from a male fruitfly is presented together with an extensive collection of genetic drivers matched to a comprehensive neuron-type catalogue.
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AntonioFR @antferrui.bsky.social · 17/03/2025
Excited to share our latest story! We found disentangled memory representations in the hippocampus that generalized across time and environments, despite the seemingly random drift and remapping of single cells. This code enabled the transfer of prior knowledge to solve new tasks
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Sarthak Chandra @sarthakc.bsky.social · 19/02/2025
1/ Our paper appeared in @Nature today! www.nature.com/articles/s41... w/ Fiete Lab and @khonamikail.bsky.social . Explains emergence of multiple grid cell modules, w/ excellent match to data! Novel mechanism for applying across vast systems from development to ecosystems. 🧵👇
nature.com
Global modules robustly emerge from local interactions and smooth gradients - Nature
The principle of peak selection is described, by which local interactions and smooth gradients drive self-organization of discrete global modules.
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Zilong Ji @zilong-ji.bsky.social · 24/02/2025
See here for our paper: www.cell.com/current-biol.... It is a great pleasure to work on this model with Tianhao, Si Wu and @neilburgess10.bsky.social. Also, I highly recommend to first read the experimental paper by @azvollan.bsky.social and colleagues: www.nature.com/articles/s41...
cell.com
A systems model of alternating theta sweeps via firing rate adaptation
Ji, Chu et al. present a network model of direction and grid cells, which generates an internal direction signal comprised of alternating left-right sweeps of encoded location and direction, based on ...
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Weinan Sun @sunw37.bsky.social · 12/02/2025
1/12 How do animals build an internal map? In our new paper, we tracked thousands of mouse CA1 neurons over days/weeks as they learned a VR navigation task. @nspruston.bsky.social & co-1st author @johanwinn.bsky.social Video: www.youtube.com/watch?v=yw_4... Paper: www.nature.com/articles/s41...
youtube.com
Learning produces an orthogonalized state machine in the hippocampus
YouTube video by Weinan Sun
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Matteo Carandini @carandinilab.net · 07/02/2025
Neuropixels and Optogenetics are delighted to announce the birth of Neuropixels Opto Combining high-resolution electrophysiology and optogenetics Today in bioRxiv 960 sites, 28 emitters, 2 colors By Lakunina, @karolinazsocha.bsky.social, Ladd, et al www.biorxiv.org/content/10.1... (1/2)
A Neuropixels Opto probe with 3 blue emitters and 3 red emitters lighting up in succession, with corresponding neural activity in different layers of the cortex.
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