#sharpwaveripples — Public Fediverse posts

New preprint dropped: __Systemic diazepam alters local hippocampal CA1 circuits and differentially affects entorhinal and CA3 inputs__

Peterson et al. (2026) #bioRxiv

https://www.biorxiv.org/content/10.64898/2026.08.18.745488v1

Really cool and amazing results that systemic diazepam obliterates hippocampal #sharpWaveRipples in vivo, particularly during the post-task rest, and disrupts representations during running.

Implies important issues that diazepam's side effects on consolidation really ought to be looked at. (All the diazepam memory tests we could find in the literature are short-term tests, no one seems to have looked at long-term consolidation, but would love citations if people have them.)

PS. To be honest, though, my favorite figure is the proof-of-efficacy in Figure 2 where decreased spiking cross-correlation directly reveals diazepam's effects on inhibition. It's so clean!

#science #neuroscience #hippocampus

@elduvelle_neuro

2/2

Importantly, not preplay, which occurs before any experience, but shortcuts, which occur after experience and allow the animal to learn the connectivity of the map.

One of the useful things lost in the publication is that Gupta et al 2010 (http://www.cell.com/neuron/abstract/S0896-6273(10)00060-7) and Gupta et al 2012 (http://www.nature.com/neuro/journal/vaop/ncurrent/abs/nn.3138.html) are the same data. 2010 is #SharpWaveRipples and 2012 is #ThetaSequences. What's cool is that the theta segments the task, while SWRs link those segments together.

#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