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

Very cool retrospective AND review of the hippocampal #SpatialCognition field from Neil Burgess:
Oscillations and Boundaries in My Route Through the Hippocampal Cognitive Map

Mentions @adredish @tom_hartley and many others, unfortunately not on Mastodon I think
#Neuroscience #PlaceCells #GridCells #Hippocampus #ThetaRhythm

📖 Vaidya et al. investigate how #hippocampal #CA1 #PlaceCells form expanding #memory representations over days. Using longitudinal in vivo recordings, they show that stable #PlaceFields progressively emerge as active cells increase their likelihood of remaining active across sessions. This gradual stabilization hinges on #behavioral‑timescale #SynapticPlasticity, offering a new model of how CA1 memories solidify w/o #CatastrophicOverwriting.

🌍 https://www.nature.com/articles/s41593-025-01986-3

#Hippocampus #Neuroscience

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

Here's a short but related 'forum' about exactly this:

Why do primates have view cells instead of place cells?

"if primates are tested in conditions where visual information is scarce, place cell-like representations may emerge."

#MartinezTrujilloLab #Neuroscience #NeuroRat #NeuroPrimate #PlaceCells #ViewCells

#PlaceCells often have elongated place fields next to an environment's boundaries.
Is there any paper where this phenomenon is directly predicted by the #SuccessorRepresentation model of place cells?

#SpatialCognition #Neuroscience #Hippocampus

Thinking about #PlaceCells and the #Hippocampus, do you think results in rats (/rodents) generalise well to humans, and conversely?

#Neuroscience #NeuroRat #NeuroHuman

#NeuroESC #JournalClub
Reading Mental exploration of future choices during immobility theta oscillations

If you've read it, will you let me know what you think?

The authors look at #ThetaSequences in a working memory task in a radial arm maze. They find theta during immobility (makes sense, e.g. we saw that in our two-goals task). They also find that theta sequences might preferentially represent the next goal (also makes sense, e.g. Hippocampal theta sequences reflect current goals)!

I have only done a quick reading so far, but am confused by a few points:

• the decoding is done on all cells (pyramidals and interneurons), shouldn't it be done on pyramidal or #PlaceCells only?
• the cell counts are quite low (often less than 40 pyrs) when I would have thought at least 50 place cells would be needed for this kind of maze. I guess that shows that #Neuropixels are not the best to record from dCA1!

• the decoded algorithm itself includes a ' position transition matrix' which seems like it would bias decoding towards realistic trajectories that the rat is about to do??? (but I probably missed something)

• also, this study is very related to this other paper, which is not discussed or even cited (😕 ):
  Assembly Responses of Hippocampal CA1 Place Cells Predict Learned Behavior in Goal-Directed Spatial Tasks on the Radial Eight-Arm Maze #CsisvariLab

Let me know what you think!

#LeutgebLab #NeuroRat #Neuroscience #SpatialCognition

#Tetrode recordings (in a bundle): did you know that you could record the same neuron on two different tetrodes?
or even three different tetrodes??

After checking that, turns out I usually have about 5-10% of neurons that are a duplicate of another neuron, in a given 8-tetrodes recording! They are pretty easy to detect with a firing rate correlation so I can remove them from analysis.
But I bet most neuron counts in published papers are inflated of that much!

Here's an example where you can see the spike plots and waveforms of 3 different, well-isolated clusters, recorded from 3 different tetrodes!

#Hexamaze #NeuroRat #Neuroscience #Ephys #Hippocampus #PlaceCells #SpikeSorting (-related)

📢 New work on the Integration of rate and phase codes by hippocampal cell assemblies to support the encoding of spatiotemporal context
https://www.nature.com/articles/s41467-024-52988-x

It was a pleasure to work with Nadine Becker, Aleks P. F. Domanski, Timothy Howe, Kipp Freud, @DurstewitzLab, and Matt Jones.
@SantAnnaPisa @BristolNeurosci @zi_mannheim @BernsteinNetwork
#Neuroscience #Hippocampus #ThetaSequences #PlaceCells

#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

It's always nice when you finally finish #SpikeSorting an old recording session and find many #PlaceCells (here, 101) 🥰

I also recently implemented a way to remove putative duplicate recordings (when spikes from the same neutron are detected in two different tetrodes) and there can be a surprisingly high amount, 6-10 % of cells as far as I can see, this is with bundles of 8 tetrodes.

#Hippocampus #Neurorat #Hexamaze

Hippocampus:Space is a latent sequence
https://www.science.org/doi/10.1126/sciadv.adm8470
https://news.ycombinator.com/item?id=41132023

* mental representation of space: emergent property of latent higher-order sequence learning
* treating space as a sequence resolves numerous phenomena
* place field mapping methodology interprets sequential neuronal responses in Euclidean terms might itself be source of anomalies

https://en.wikipedia.org/wiki/Grid_cell
https://en.wikipedia.org/wiki/Place_cell

#neuroscience #hippocampus #GridCells #PlaceCells #neurobiology #MentalProcesses

Ok maybe this is the best cluster space ever
(also, from an implant that’s almost 4 months old!)
#Tetrodes #NeuroRat #Hippocampus #PlaceCells

If a #NeuroRat running in a maze hears one of his #PlaceCells activating (from the computer) as he enters a specific location… does the sound become a cue??? 🤯

#Hippocampus #Navigation #Neuroscience

@marisosa @giocomo congrats and thank you for this great work!!
I (personally - but curious if you also see it that way) interpret it as showing that reward delivery is used as a localization cue (at least in VR) by the hippocampus. Previous studies hinted at this but yours clearly demonstrates it, including the distance to cue coding that we often see with place cells and walls!

And it makes sense from a general coding point of view: it is likely that the hippocampus doesn’t discriminate the type of cues that are used for localization - if inputs are consistently occurring together, it will associate them together, regardless of their original nature…

#Hippocampus #RewardCoding #PlaceCells

@eliezyer I’d say figshare! You can post things and decide of the sharing license and people can download them and cite them.

For example we have a video of #PlaceCells there: https://figshare.com/articles/media/Co-recorded_place_cells_51_mins_10_cells/8063321

Has anyone ever seen #HipocampalReplay doing a u-turn (for example in the middle of a linear track)? We should be able to see that at least with bayesian decoding no?

The closest I can think of is Wu & Foster (2014); see screenshots - but it only shows replay taking the “reverse” order at choice points, not changing direction mid-track.

(edit: added hashtags)
#Neuroscience #Hippocampus #PlaceCells

I love #GridCells but I have to say their influence for any neural process is probably highly over-inflated.

When you actually record from #MEC you see there are so many non-grid cells… it’s really a huge contrast to #Hippocampus where most of the cells are going to be #PlaceCells either in the current environment or another.

I feel like we can remember quite well where we were when reading a specific book. Isn’t that weird that you can associate the different imagined places & events of the story, and the actual physical place you had while reading?
I guess it’s the same for video games…

This makes me want to record #PlaceCells in VR but focus on the real-life reference frame… 👀