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Reposted by Tamara Gedankien

Tim Guth @timaguth.bsky.social · 11/08/2025

Excited to share our new paper on theta-phase locking of single neurons during human spatial memory: www.nature.com/articles/s41... With @lukaskunz.bsky.social, Joshua Jacobs, and our colleagues from the University of Freiburg

Neuronal theta-phase locking increased during periods of elevated theta power, when aperiodic activity exhibited steeper slopes, and when clear theta oscillations were detected. Theta-phase locking was similarly strong during the successful and unsuccessful encoding and retrieval of memories. Some neurons changed their preferred theta phases between encoding and retrieval.

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Reposted by Tamara Gedankien

Luca Kolibius @lucakolibius.bsky.social · 02/07/2025

Despite recent criticism from Quiroga to our claim that Concept Neurons emerge from Conjunctive Coding Neurons we claim: “And yet, the hippocampus codes conjunctively!”. We hope it sparks a smile (and maybe a few debates). Read here: tinyurl.com/3ycv3vj2

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Reposted by Tamara Gedankien

Marta Silva @martamasilva.bsky.social · 01/07/2025

🧠 Paper out! We investigated how hippocampal and cortical ripples support memory during movie watching. We found that: 🎬 Hippocampal ripples mark event boundaries 🧩 Cortical ripples predict later recall Ripples may help transform real-life experiences into lasting memories! rdcu.be/eui9l

rdcu.be

Movie-watching evokes ripple-like activity within events and at event boundaries

Nature Communications - The neural processes involved in memory formation for realistic experiences remain poorly understood. Here, the authors found that ripple-like activity in the human...

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Reposted by Tamara Gedankien

bioRxiv Neuroscience @biorxiv-neursci.bsky.social · 13/05/2025

Cholinergic blockade reveals role for human hippocampal theta in encoding but not retrieval www.biorxiv.org/content/10.1101/202…

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Tamara Gedankien @gedankien.bsky.social · 14/05/2025

Bottom line: 📉 Theta ≠ Retrieval 📈 Theta = Encoding/Updating This subtle but important shift reframes how we think about the neural basis of memory, and why cholinergic drugs help some processes and not others. Full details ⬇ www.biorxiv.org/content/10.1...

biorxiv.org

Cholinergic blockade reveals role for human hippocampal theta in encoding but not retrieval

Cholinergic dysfunction is a hallmark of Alzheimer's disease and other memory disorders. Yet, the neurophysiological mechanisms linking cholinergic signaling to memory remain poorly understood. In thi...

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Tamara Gedankien @gedankien.bsky.social · 14/05/2025

In analyses led by @ZabehErfan, we also show that neural dynamics under cholinergic blockade can be decoded from low-dimensional features of LFPs across electrodes.

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Tamara Gedankien @gedankien.bsky.social · 14/05/2025

This has big implications: 🧬 For memory models: Theta may unify encoding & re-encoding, not retrieval per se 🧠 For neurophysiology: Reinstatement might reflect reactivation of an encoding mode, not just stored content 🧪 For Alzheimer’s: Targets for modulating cholinergic tone may need rethinking

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Tamara Gedankien @gedankien.bsky.social · 14/05/2025

Our data show: – Theta power & phase reset are disrupted by cholinergic blockade at retrieval – But memory remains intact – Reinstatement of spectral patterns from encoding is also impaired → Retrieval still works without theta, but maybe in a different form.

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Tamara Gedankien @gedankien.bsky.social · 14/05/2025

This challenges long-held theories that hippocampal theta reflects retrieval-specific computations. Instead, we propose a unifying framework: theta during retrieval reflects re-engagement of encoding-related neural states, perhaps to update or integrate memory—not retrieve it.

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Tamara Gedankien @gedankien.bsky.social · 14/05/2025

When scopolamine was present at encoding, patients had selective recollection deficits and disrupted hippocampal theta. But when the drug was present only at retrieval, memory was spared—even though theta power, phase reset, and reinstatement were disrupted.

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Tamara Gedankien @gedankien.bsky.social · 14/05/2025

We gave scopolamine (a muscarinic cholinergic blocker) to epilepsy patients with implanted hippocampal electrodes as they performed a memory task. By injecting the drug before retrieval vs. before encoding we could tease apart the role of theta oscillations at each memory stage.

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Tamara Gedankien @gedankien.bsky.social · 14/05/2025

Hi Bluesky! First post here. Kicking things off with a new preprint. 🧠 Using human iEEG + pharmacology, we asked: is hippocampal theta required for retrieval? Turns out it’s not. Instead, it may reflect a reinstated encoding mode. Thread below. www.biorxiv.org/content/10.1...

biorxiv.org

Cholinergic blockade reveals role for human hippocampal theta in encoding but not retrieval

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