5/5 Big thanks to the team and collaborators @clykken.bsky.social @beneuroscience.bsky.social @anagelhus.bsky.social @jocarpenter.bsky.social @matteoguardamagna.bsky.social @m-bmoser.bsky.social @kavlintnu.bsky.social
#Neuroscience #GridCells #PlaceCells #EpisodicMemory #Neuropixels #KiloNeurons

4/5 Conclusion: Independent phase changes across grid modules are sufficient to generate a vast array of distinct hippocampal representations.

Why this matters: Such combinatorial flexibility is a key requirement for forming episodic memories, offering a mechanism for high-capacity memory.

3/5 We discovered that when grid cell modules realigned differently between environments, hippocampal place cells remapped. Strikingly, the extent of this remapping was directly predicted by the disparity in phase changes across grid modules.

2/5 After two decades, our hypothesis for this space-to-memory transformation finally met a decisive test.
Led by our outstanding postdoc @clykken.bsky.social, we performed multi-area #Neuropixels recordings simultaneously from hippocampal place cells and multiple MEC grid cells modules in rats 🧠

Excellent work, and very interesting observations - congratulations!

🧠⏳ This discovery would not be possible without #Neuropixels and the dedication and talent of @beneuroscience.bsky.social @clykken.bsky.social @nachopolti.bsky.social @m-bmoser.bsky.social at the @kavlintnu.bsky.social (2/2)

Thanks! Not merely expressing future trajectories. The sweeps also extend into spaces not visited, and persist during sleep.

Sweeps represent an efficient mechanism for scanning locations in the ambient environment during navigation. Sweep direction could be explained by an algorithm that maximizes cumulative coverage of surrounding space.

Sweeps in place cells are delayed compared to sweeps in grid cells, pointing to an entorhinal origin. 📍

Sweeps are accompanied by, and aligned with, a similarly alternating directional signal in a discrete population of direction-tuned cells with putative connections to the #gridcells 🗺️

Sweeps extend into never-visited space inaccessible to the animal, and persist during REM sleep, pointing to an intrinsic “hardwired” network mechanism for the phenomenon. 🧹🌋🧹🌊🧹

Sweeps are time-locked to the local theta rhythm. Each theta cycle has one sweep. Sweeps alternate their direction between left and right on successive theta cycles.

Populations of grid cells and place cells encode a position signal that within a 125-ms theta cycle sweeps linearly outwards from the animal’s location into the ambient environment, alternating stereotypically between left and right directions. 🧹🧹🧹