Abraham Zelalem Vollan
@azvollan.bsky.social
PhD student in the Moser lab. Spatial cognition, grid cells, population dynamics, high-density ephys. MD from 🇳🇴
Pinned
Excited to share that our paper is now published in Nature! In this study, we uncovered a grid-cell-based circuit in medial entorhinal cortex that probes the surrounding environment with theta-paced, sweeping spatial representations 🧵
www.nature.com/articles/s41...
www.nature.com/articles/s41...
Reposted by Abraham Zelalem Vollan
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...
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...
September 25, 2025 at 4:15 AM
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...
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...
Reposted by Abraham Zelalem Vollan
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
🚨 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
September 17, 2025 at 7:33 PM
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
🚨 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
Reposted by Abraham Zelalem Vollan
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/evWtz
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...
rdcu.be
July 12, 2025 at 5:09 PM
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/evWtz
Reposted by Abraham Zelalem Vollan
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...
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...
Replay and representation dynamics in the hippocampus of freely flying bats - Nature
Nature - Replay and representation dynamics in the hippocampus of freely flying bats
www.nature.com
July 9, 2025 at 3:08 PM
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...
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...
Reposted by Abraham Zelalem Vollan
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.
Interleaved Replay of Novel and Familiar Memory Traces During Slow-Wave Sleep Prevents Catastrophic Forgetting https://www.biorxiv.org/content/10.1101/2025.06.25.661579v1
June 30, 2025 at 8:25 AM
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.
Reposted by Abraham Zelalem Vollan
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/...
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/...
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...
www.science.org
June 26, 2025 at 6:06 PM
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/...
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/...
Reposted by Abraham Zelalem Vollan
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 🧵👇
🔗 www.science.org/doi/10.1126/...
Here's a quick summary of what we found 🧵👇
June 26, 2025 at 6:15 PM
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 🧵👇
🔗 www.science.org/doi/10.1126/...
Here's a quick summary of what we found 🧵👇
Reposted by Abraham Zelalem Vollan
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
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
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 ...
www.nature.com
May 28, 2025 at 12:19 PM
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
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
Reposted by Abraham Zelalem Vollan
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...
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...
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.
www.nature.com
May 28, 2025 at 3:32 PM
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...
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...
Reposted by Abraham Zelalem Vollan
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
May 23, 2025 at 4:19 PM
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
Reposted by Abraham Zelalem Vollan
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/book/59509?s...
The Hippocampus Book
Abstract. The Hippocampus Book investigates the structure, function and pathology of the hippocampus and related cortical areas. It highlights the importan
academic.oup.com
April 26, 2025 at 4:27 AM
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/book/59509?s...
Reposted by Abraham Zelalem Vollan
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
Link: www.nature.com/articles/s41...
🧵highlights below
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...
www.nature.com
April 15, 2025 at 6:26 AM
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
Link: www.nature.com/articles/s41...
🧵highlights below
Reposted by Abraham Zelalem Vollan
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...
🔗 www.nature.com/articles/s41...
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.
www.nature.com
March 27, 2025 at 10:58 PM
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...
🔗 www.nature.com/articles/s41...
Reposted by Abraham Zelalem Vollan
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
March 17, 2025 at 1:35 AM
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
Reposted by Abraham Zelalem Vollan
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. 🧵👇
Explains emergence of multiple grid cell modules, w/ excellent match to data! Novel mechanism for applying across vast systems from development to ecosystems. 🧵👇
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.
www.nature.com
February 19, 2025 at 11:20 PM
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. 🧵👇
Explains emergence of multiple grid cell modules, w/ excellent match to data! Novel mechanism for applying across vast systems from development to ecosystems. 🧵👇
Reposted by Abraham Zelalem Vollan
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...
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 ...
www.cell.com
February 24, 2025 at 8:27 PM
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...
Reposted by Abraham Zelalem Vollan
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...
Video: www.youtube.com/watch?v=yw_4...
Paper: www.nature.com/articles/s41...
Learning produces an orthogonalized state machine in the hippocampus
YouTube video by Weinan Sun
www.youtube.com
February 12, 2025 at 7:36 PM
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...
Video: www.youtube.com/watch?v=yw_4...
Paper: www.nature.com/articles/s41...
Reposted by Abraham Zelalem Vollan
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)
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)
February 7, 2025 at 9:16 AM
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)
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)
Excited to share that our paper is now published in Nature! In this study, we uncovered a grid-cell-based circuit in medial entorhinal cortex that probes the surrounding environment with theta-paced, sweeping spatial representations 🧵
www.nature.com/articles/s41...
www.nature.com/articles/s41...
February 4, 2025 at 9:12 PM
Excited to share that our paper is now published in Nature! In this study, we uncovered a grid-cell-based circuit in medial entorhinal cortex that probes the surrounding environment with theta-paced, sweeping spatial representations 🧵
www.nature.com/articles/s41...
www.nature.com/articles/s41...
Reposted by Abraham Zelalem Vollan
Out now in @nature.com
Left-right-alternating theta sweeps in
entorhinal-hippocampal maps of space
@azvollan.bsky.social @rjgardner.bsky.social
@m-bmoser.bsky.social @kavlintnu.bsky.social
@kavlifoundation.bsky.social @ercresearch.bsky.social #KiloNeurons
🧹🧹🧹
www.nature.com/articles/s41...
Left-right-alternating theta sweeps in
entorhinal-hippocampal maps of space
@azvollan.bsky.social @rjgardner.bsky.social
@m-bmoser.bsky.social @kavlintnu.bsky.social
@kavlifoundation.bsky.social @ercresearch.bsky.social #KiloNeurons
🧹🧹🧹
www.nature.com/articles/s41...
www.nature.com
February 3, 2025 at 4:19 PM
Out now in @nature.com
Left-right-alternating theta sweeps in
entorhinal-hippocampal maps of space
@azvollan.bsky.social @rjgardner.bsky.social
@m-bmoser.bsky.social @kavlintnu.bsky.social
@kavlifoundation.bsky.social @ercresearch.bsky.social #KiloNeurons
🧹🧹🧹
www.nature.com/articles/s41...
Left-right-alternating theta sweeps in
entorhinal-hippocampal maps of space
@azvollan.bsky.social @rjgardner.bsky.social
@m-bmoser.bsky.social @kavlintnu.bsky.social
@kavlifoundation.bsky.social @ercresearch.bsky.social #KiloNeurons
🧹🧹🧹
www.nature.com/articles/s41...
Reposted by Abraham Zelalem Vollan
Grid cells have a geometry in time. Thanks to @azvollan.bsky.social l & @rjgardner.bsky.social for this heroic discovery. @ercresearch.bsky.social
#KiloNeurons @m-bmoser.bsky.social @kavlintnu.bsky.social @nature.com
@kavlifoundation.bsky.social
www.nature.com/articles/s41...
#KiloNeurons @m-bmoser.bsky.social @kavlintnu.bsky.social @nature.com
@kavlifoundation.bsky.social
www.nature.com/articles/s41...
Left–right-alternating theta sweeps in entorhinal–hippocampal maps of space - Nature
A study in rats proposes a mechanism for how the brain maps the surrounding environment, including places it has never seen, by alternating left and right forward sweeps in successive theta cycles.
www.nature.com
February 3, 2025 at 4:18 PM
Grid cells have a geometry in time. Thanks to @azvollan.bsky.social l & @rjgardner.bsky.social for this heroic discovery. @ercresearch.bsky.social
#KiloNeurons @m-bmoser.bsky.social @kavlintnu.bsky.social @nature.com
@kavlifoundation.bsky.social
www.nature.com/articles/s41...
#KiloNeurons @m-bmoser.bsky.social @kavlintnu.bsky.social @nature.com
@kavlifoundation.bsky.social
www.nature.com/articles/s41...
Reposted by Abraham Zelalem Vollan
1/19 I’m thrilled that my postdoctoral work, with John Widloski and David Foster is now out in @science.org, along with a wonderful preview by Daniel Bendor!
The time course and organization of hippocampal replay
The mechanisms by which the brain replays neural activity sequences remain unknown. Recording from large ensembles of hippocampal place cells in freely behaving rats, we observed that replay content i...
www.science.org
January 31, 2025 at 9:14 PM
1/19 I’m thrilled that my postdoctoral work, with John Widloski and David Foster is now out in @science.org, along with a wonderful preview by Daniel Bendor!
Reposted by Abraham Zelalem Vollan
It’s an incredible feeling to see something you’ve poured your heart into come to life. This work was born from my curiosity about hippocampal “cognitive tuning.”
Our interpretation of the environment depends on our actions, constantly evolving as we pursue our goals
www.nature.com/articles/s41...
Our interpretation of the environment depends on our actions, constantly evolving as we pursue our goals
www.nature.com/articles/s41...
Hippocampal neuronal activity is aligned with action plans - Nature
Using high-density electrophysiological recordings, how internally generated cell assemblies are updated by action plans to meet external goals is explored.
www.nature.com
January 9, 2025 at 10:36 PM
It’s an incredible feeling to see something you’ve poured your heart into come to life. This work was born from my curiosity about hippocampal “cognitive tuning.”
Our interpretation of the environment depends on our actions, constantly evolving as we pursue our goals
www.nature.com/articles/s41...
Our interpretation of the environment depends on our actions, constantly evolving as we pursue our goals
www.nature.com/articles/s41...
Reposted by Abraham Zelalem Vollan
1/3 How does visual input affect the heading direction (HD) network?
In our latest lab preprint, Ryosuke presents "visual landmarks" to larval zebrafish and shows that the HD network tethers to the visual environment. The experiments are again inspired by the beautiful recent work in Drosophila.
In our latest lab preprint, Ryosuke presents "visual landmarks" to larval zebrafish and shows that the HD network tethers to the visual environment. The experiments are again inspired by the beautiful recent work in Drosophila.
December 20, 2024 at 8:34 AM
1/3 How does visual input affect the heading direction (HD) network?
In our latest lab preprint, Ryosuke presents "visual landmarks" to larval zebrafish and shows that the HD network tethers to the visual environment. The experiments are again inspired by the beautiful recent work in Drosophila.
In our latest lab preprint, Ryosuke presents "visual landmarks" to larval zebrafish and shows that the HD network tethers to the visual environment. The experiments are again inspired by the beautiful recent work in Drosophila.
Reposted by Abraham Zelalem Vollan
Shocking news! I got a FRIPRO grant by the Research Council of Norway. Lots of thanks to my institute @kavlintnu.bsky.social, my mentors and my lab members for the support! Contact me if you want to join us developing cool miniature microscopes #Mini2P for studying exciting neuroscience questions!
December 5, 2024 at 10:18 PM
Shocking news! I got a FRIPRO grant by the Research Council of Norway. Lots of thanks to my institute @kavlintnu.bsky.social, my mentors and my lab members for the support! Contact me if you want to join us developing cool miniature microscopes #Mini2P for studying exciting neuroscience questions!