#hippocampalreplay — Public Fediverse posts

Hi all,

Save the date: The 6th International Sleep Replay Workshop will be held in Glasgow, UK, on Monday the 26th of July 2027, just ahead of the International Conference on Memory!

As always, the workshop will consist of symposia, talks, and discussion groups focused on the interface between sleep and memory. We will share registration info and additional details with the ISRW mailing list later in 2026.

The workshop will start early on the 26th, so we recommend arriving in Glasgow the day before.

Thinking of coming to ICOM, ISRW or both? Let me know in comments!

Looking forward to seeing you there 😊

Organizing Committee for ISRW-VI
James Antony (California Polytechnic State University)
Eleonore Duvelle (University of Glasgow)
Gordon Feld (Central Institute of Mental Health, Mannheim)
Eva Kimel (University of York)
Penny Lewis (Cardiff University)
Eitan Schechtman (University of California Irvine)
Jing Zhang (Harvard University)

#Neuroscience #Research #AcademicChatter #NeuroConf #Memory #HippocampalReplay

RE: https://neuromatch.social/@elduvelle_neuro/116850195155224254

Hi all, please check our latest preprint (Tirole et al., 2026) that breaks the dogma of #HippocampalReplay being value-dependent!!

(but of course if there's anything we did not account for, please let us know, that's what preprints are for!!)

#SpatialCognition #Hippocampus #MemoryConsolidation

10/12
All taken together:

• reward value does not influence replay rates, inviting a re-examination of previous findings
• Instead, behavioural state has a clear influence on ‘enabling’ replay; more movement, even below the usual speed threshold of 5 cm/s, leads to less replay.
• recency strongly influences replay, during wakefulness and sleep
• local replay specifically helps bind newly-recruited place cells into the #CognitiveMap
• the relative replay rates of episodes during sleep can be predicted by how far back in the past the episode happened and how much it has been replayed since

#HippocampalReplay #BehaviourNotValue #RecencyEffect
10/12

7 / 12
Are you ready for PART 2?...

That’s not just it! We also found another strong modulator of replay (hence the article’s title): time since the experience, i.e. episode ‘recency’: the most recent episodes were replayed the most afterwards, whether during rest after running each track, or during sleep.

This finding might explain why we tend to remember better the last experience in a series! And it means that we all need to be more careful about what we do just before going to sleep (at least, if you don’t want your doom-scrolling to be consolidated) 😅

PS: this is my favourite figure of the entire manuscript 🤗 Margot really has a knack for beautiful clarity 🤩

7/12
#HippocampalReplay #NeuroRat #RecencyEffect #RecencyBias

~ New preprint, new thread! ~
My former colleagues at UCL Margot Tirole and Dan Bendor (not on Masto) have a new #HippocampalReplay preprint out, to which I contributed a little! Check out our thread and don't hesitate to share and comment!

Why do we remember some experiences more than others?

Reactivations of neurons in the #Hippocampus (“replay”), particularly during sleep, may help consolidate memories; but when many experiences occur before going to bed, the brain must sort out what is worth replaying 😴

We investigated whether reward or recency helped prioritize experiences for replay in freely-moving rats. Surprisingly, we found that reward value does not influence replay! Instead, episode recency has a major effect, with the most recent episode being replayed the most!

Check the preprint for more: Time, but not reward, shapes replay-based episodic prioritization
... or read on for a thread on the main results! ⏬

#NeuroRat #SpatialMemory #MemoryConsolidation #Neuroscience #MastoThread
1/12 🧵

Preparing some slides on my favourite topic of the moment - #HippocampalReplay - for some colleagues, starting from lecture slides I made about 8 years ago...
and I keep crossing stuff or adding "BUT see xx" or "actually not" or "Now controversial!" to about half of the results that I was taking from granted 8 years ago 👀

Is there any such thing as a scientific fact?!

#Hippocampus #AcademicChatter

Here's a very interesting paper from the #KeinathLab:

Environmental representations in mouse hippocampal CA1 reflect the predictive structure of navigation

In the absence of task or reward, #PlaceCells appear to reflect the past history of behavioural biases, i.e. the accumulated past paths taken by each individual mouse. I am actually starting to think that #HippocampalReplay is doing a similar thing - just reflecting an average of the individual's past behaviour, and that all supposed "coding" of reward is purely driven by this (notice how reward "coding" always seems to happen in cases where reward biases the behavioural patterns..) 👀🧠🤔

#Neuroscience #Hippocampus #NeuroMice

If you want to study #HippocampalReplay... Use ephys, not #CalciumImaging!!

(Calcium imaging doesn't detect single spikes well, but replay mostly involves single spikes)
#Neuroscience #SpatialCognition #Hippocampus

Thinking of organizing a regular (every 2 months) full-online journal club on #HippocampalReplay (and more generally, internally-generated sequences phenomena).

Would anyone from here be interested? I had been organizing something similar (IGSJC) where the first author presents a recent paper, but it has only been every year or so, this would be more regular and not necessarily presented by the first author.

The goal would be to keep up with the replay literature with a critical (and fair) approach. If you are interested can you let me know your timezone? 🧠

#JournalClub #Neuroscience #Hippocampus

Heading off to the #EBBS2025 conference in Bordeaux!
I will present a poster there on our latest #HippocampalReplay findings (replay does not do planning, but seems to support reward-learning instead, in a flexible spatial planning task), and co-lead a symposium with the great John Widloski, also on replay!
We have an amazing speaker list with John himself, Lisa Genzel, Jacob Bakermans and Elisa Massi!

Check the full programme here: https://ebbs2025.azuleon.org/programme_overview

Will you be there?!

#Neuroscience #NeuroConf #PlaceCells #Hippocampus

I keep going back to this question about #TemporalCreditAssignment and #HippocampalReplay:
As an "agent" you want to learn the value of places and which places are likely to lead to reward;

-1) if a place leads to higher than expected reward, you'll want to propagate back the reward info from the reward throughout the places that led to the reward. If replay does that you should see an increase of replay at a new reward site and the replay sequences should start at the reward and reflect what you just did to reach it. Right?

-2) if a place leads to lower than expected reward, you'll also want to propagate that lowered value, pretty much in the same way, so if replay does that you should see a similar replay rate and content for increased OR decreased reward sites. Right?

-3) if a place has had unchanged reward for a while and you're just in exploitation mode (just going there again and again because you know that's the best place to go to in the environment) then you shouldn't need to update anything and replay rate should be quite low at that unchanged reward side. Right?

That's not at all what replay is doing IRL, so does that mean replay is not used for temporal credit assignment? Or did I (very likely) miss something?

#Neuroscience #ComputationalNeuroscience #DecisionMaking #Hippocampus

Recent opinion piece on awake #HippocampalReplay which takes together a lot of recent results and concludes that:

• no, the evidence does not point towards a role of replay in immediate planning
• instead, replay might be used to tag memories for future consolidation,
• and it might be triggered by prediction error (e.g. difference of reward, novelty, ...)

Awake replay: off the clock but on the job

#mvdmLab #BendorLab

This paper ⬆️ from Caitlin Mallory is now out in Science! Great to see a #HippocampalReplay paper there, and very well deserved!

The time course and organization of hippocampal replay
From #FosterLab, maybe soon the #MalloryLab??

#Hippocampus #NeuroRat

@johnwidloski and I are co-organizing a symposium on #HippocampalReplay at the #EBBS25 in Bordeaux!

Our goal: From the state of the art in awake replay models & existing data, determine the next big questions and most informative future experiments to finally figure out what is awake replay for!

Our speakers:

• John Widloski
• Lisa Genzel
• Jacob Bakermans
• Elisa Massi

Meeting dates: 28 June to 1 July 2025 (our symposium is on the last day

Programme: https://ebbs2025.azuleon.org/programme

The abstract submission deadline for posters (and early bird registration) is on 31 March 2025 - I hope to see you there!

#Neuroscience #NeuroSymp #NeuroConf #Hippocampus

A short commentary by the great Anna Gillespie on awake replay:

Ruminating on replay during the awake state

#GillespieLab (https://www.gillespie-lab.com/)

Interesting bits:

"replay during sleep is generally thought to occur in the forward direction"

I believe this is true too, but has anyone actually analyzed it? It could be done on several existing datasets...

"The idea that awake replay might serve a planning role was broadly adopted by the field, even though direct experimental evidence [...] has been slow to emerge"

YES because replay is not related to immediate planning, however nice it would be if it was

"We, as a field, also need to be more precise with our terminology. For instance, what exactly should we consider evidence of ‘planning’ or ‘deliberation’ in an animal model? "

YES

Related: history of the 'genesis' of #ThetaSequences narrated in this retrospective by @adredish: Mental Time Travel: A Retrospective
(original post:
https://neuromatch.social/@adredish/113662497894186335) #RedishLab

I'd actually argue that replay, and not theta sequences, might be closer to mental time-travel... but we probably don't know enough about either to be sure yet!

#Neuroscience #HippocampalReplay #Hippocampus

I keep seeing studies (especially computational ones) citing the Ambrose et al. 2016 paper as proof that #HippocampalReplay is modulated by reward.

I don't think this result can be trusted...

1. The time spent at low-speed at reward sites wasn't controlled. Rats left the less rewarded sites much faster, and would probably move a lot more when less reward was present (not analyzed I think).
2. The amount of ripples or replay is analysed in count per second. I believe this means seconds of any kind of behaviour, not just rest or low speed. But #Ripples and the related #Replay only happens when the rat is quasi-immobile. At low speed you might have 1 replay per second, while when moving it will be 0/s.
3. A recent preprint (Mallory et al., 2024) suggests that after a few seconds at a reward location, reverse replay dominates. Ambrose et al. specifically show an increase of reverse replay for the x4 reward vs x1 reward. If rats indeed spent more time at the most rewarded location, they would be in reverse replay mode, fully explaining the results without the need to invoke any kind of value processing. Note: the reduced replay result was not specific to reverse replay for 1 vs 0, probably because the rats didn't stay immobile long enough to get some of those forward replays during the earlier reward period.

I might have missed something (if so let me know) but I am now completely unconvinced by the 2016 paper. What do you all think?

#Hippocampus #ValueCoding
Edit: added some more info after re-reading the 2016 paper

Just co-submitted a #Symposium proposal for #EBBS25! Yes it's on #HippocampalReplay and we got an amazing speaker line-up, I hope it gets in 🤞
(It's my first...)

Hi #Neuroscientists, do you know someone working on #HippocampalReplay (either experimentally or computationally) who might want to go to #EBBS25 (it's in Bordeaux, France)?

I'm thinking about submitting a symposium proposal and don't want to be biased towards only people I already know.. 🙏

#Hippocampus

#JournalClub on Closed-loop modulation of remote hippocampal representations with neurofeedback, from #FrankLab: little summary + comments.

• The goal is to see if rats can deliberately reactivate internal representations, without external cues.
• The authors design a closed-loop system that does clusterless real-time decoding of position and rewards the rats when they reactivate a specific maze arm end.
  
• The rats go through a gradual training process: first getting reward on the actual maze (a T-maze), then getting reward in the home box when they orient towards the target arm of the maze [head-direction task], then getting reward in the home box when they reactivate the representation of the target maze end [neurofeedback task].
• The rat's performance is not too bad given the difficulty of the task, kudos to Rat2 who seemed to really know what he was doing.
• interestingly, the reactivations do not happen during #SharpWaveRipples, and not really during theta either, just during an uncharacterised LFP state.
• Little caveat 1: as far as I can see, the head-direction of the rats is not shown in any plot and it is not possible to say if the rats might still be doing the head-direction task during the neurofeedback task. That being said, the rats clearly reactivate the target arm more in the neurofeedback than head-direction task, which is quite convincing.

• Little caveat 2: the performance is always shown in terms of total rewards collected, and not reward rate. So in different sessions rats might reach the maximum reward but take twice the time. Showing reward rate would be more informative.

• conclusion: this is pretty cool, but we would really need to know about the head-direction.

• question for the audience: what do you think the rats "think about" during those reactivation moments??

#Neuroscience #HippocampalReplay (not really) #ThetaSequences (not really) #PlaceCells #NeuroRat #Hippocampus

(okay maybe not in the whole of Neuroscience but more like in the #HippocampalReplay world)

We did a special #JournalClub on this (getting a group of experts together online to discuss it while it is presented by the first author) and it was really cool. The results are really convincing, which is quite rare for #HippocampalReplay papers! They are also quite likely to explain results from many other studies. And they raise the question of what is replay for if it just acts basically the same in a very basic linear-track task and a complex hidden-goal navigation task... 🤔

#IGSJC series (Internally-Generated-Sequences Journal Club)

New preprint from Caitlin Mallory / #FosterLab about #HippocampalReplay and its links with the #MedialEntorhinalCortex - looks really cool!!

Self-avoidance dominates the selection of hippocampal replay

#Need2Read #Hippocampus

New #FosterLab preprint, looking very interesting, as usual:
Replay without sharp wave ripples in a spatial memory task

#HippocampalReplay #HippocampalRipples #Hippocampus #SpatialNavigation #Need2Read

@mrspaghetti @dlevenstein looks pretty cool, thanks for sharing!
#HippocampalReplay #Need2Read

@PhiloNeuroScie looks very interesting - thanks for sharing!!
I wonder how related it is to this recent paper from the #BendorLab: The role of experience in prioritizing hippocampal replay

#HippocampalReplay #Neuroscience #Hippocampus #Need2Read

@LMPrida @perpl_lab @acnavasolive @saman @cogneurophys 🥳so happy this is out! I wasn’t sure how the ML models would perform, given the frequency shift in monkey (and human) SWRs, and the larger post-ripple wave compared to those in mice. But, a few models rose to the top straightaway and performed even better with modest “top up” training! 📈Now I’m curious how the #opensource toolbox will perform on human hippocampal data. ……..➡️👩‍🔬both senior authors and one lead author were #womenInSTEM working across two continents, and the original multi-model testing was formulated as a hackathon that included #diverserepresentation ! #neuroai #ann #cnn #neuroscience #hippocampus #HippocampalReplay #internationalwomensday

@thetransmitter
Oh yes - like this (#Hippocampal #ThetaSequences):
https://m.youtube.com/watch?v=IU8wKl5PcLU

Or this (#HippocampalReplay):
https://m.youtube.com/watch?v=q0kD2RSejRo

(source: #vanDerMeerLab)

Reading two very interesting articles for #JournalClub:

• Replay of incidentally encoded episodic memories in the rat
  (spoiler alert: it’s not actually about replay as in hippocampal replay)
  
• Hippocampal sequences span experience relative to rewards
  (this one is about #HippocampalReplay)
  

also, not that anybody cares but I met first author Mari Sosa for the first time at #SFN23 and it was so great to finally see her IRL! I wish she was on here!

Sad that our #Cosyne24 workshop didn’t get accepted… it would have been so cool 🥲
(It was on #HippocampalReplay)

Seen on twitter, from #BendorLab:

“One month left to submit abstracts for the hippocampus green meeting
http://hippocampusgreen.net/wp/
Join us for this 2-day conference focusing on hippocampal physiology, network dynamics, and the phenomenon of replay in freely behaving animal models (London, June 10-11, 2024)”

Looks pretty cool! If only I could plan my life that far in advance 😅

#Hippocampus #HippocampalReplay #NeuroConf

@SWC_Neuro Well I can tell you one thing - it’s not via #HippocampalReplay ;)

I have presented this poster on #HippocampalReplay at #SFN23 !

I'm also uploading the poster as an image here, and it's on the SFN website: https://cattendee.abstractsonline.com/meeting/10892/presentation/33535

Little summary below:

Our goal was to investigate if replay of hippocampal #PlaceCells was indeed reflecting immediate #SpatialPlanning.

The existing literature is a little unclear: some studies find 'planning replay' and some do not. Most of the time, planning is not dissociated from reward consumption in these studies as they can generally be simplified to an alternation between two rewarded locations. In our case, we separate the location of planning from the location of reward and focus on replay happening at the planning time.

At the location of planning, we find that:

1) there is actually almost no replay at the time of planning
2) the rare 'start replay' events do NOT over-represent the future trajectory, or even the goal
3) the rare 'start replay' events do not differ for successful vs unsuccessful planning.

At the goal location, we find that:

4) Many replays occur at the goal, even before the reward delivery!
5) 'goal replays' strongly over-represent the goal (either before or after reward delivery)
6) 'goal replays' do not over-represent the current trajectory compared to the alternative trajectory, or even the optimal path if the less-optimal path was taken
7) 'goal replays' were strongly affected by errors and were quasi-absent during error trials (choosing an unrewarded end box)

In conclusion:

Reward (received or expected), but not planning, drives hippocampal replay!

Let me know if you have any questions after looking at the poster :D

Edit: updated because this is in the past now (but hoping to publish it soon!)

Question for #HippocampalReplay people:

Can you think of any experiments where awake replay is observed outside of a goal / reward location?

(Specifically interested in replay i.e. sharp-wave / ripple - related #Reactivations, not theta sequences)

#Hippocampus #SWR

I’ll be presenting a poster about #HippocampalReplay at #SFN2023!

The session: https://www.abstractsonline.com/pp8/#!/10892/session/1900

The poster: Hippocampal replay does not reflect trajectory planning in a spatial planning task

The date: November 15, 2023, 8:00 AM - 12:00 PM

The location: Walter E. Washington Convention center, Washington D.C., WCC Halls A-C

Will you be there?!? There is also an online version!

Teaser video ⬇️
#Hippocampus #PlaceCells #FlexibleNavigation #NeuroRat #Neuroscience
1/2

#Introduction of my #Neuroscience-oriented account! 🧠​

I am a postdoctoral researcher investigating #NeuroRats 🐀​ doing flexible #Navigation 🗺️​ and how their #Hippocampus might support this fascinating ability.
Is it #PlaceCells?
Is it #HippocampalReplay?
​Is it #SplitterCells?
Is it everything, everywhere (... yes, yes, all at once)?

This account will post, boost and follow specifically neuroscience content, don't hesitate to tag it when relevant.

Followers, please tell us about yourself under my pinned tweet!

⤴️​ After reading this #NeuroPaper I have to say it is much more interesting than what I thought at first view! And particularly well-written, illustrated and clear!

A must-read for anyone interested in #Dopamine #ReinforcementLearning #Reward #Value #RewardPredictionError #Navigation #Shortcuts #Detours #CognitiveMap (maybe) #Inference with some future hints of #HippocampalReplay !
Congrats to all authors, let me know if any is on here!

New computational model of #HippocampalReplay:
A recurrent network model of planning explains hippocampal replay and human behavior

By @KrisJensen et al.
It looks super interesting! But let me tell you: this is not what hippocampal replay does in rodents… replay is not for planning.🤷‍♂️​

#Hippocampus #Replay