@basharjaankhan @benjamin_dunn @davidt

Sure! When I'm talking about place cells, I am referring to neurons in the hippocampus that respond to specific locations in an environment. The tuning of place cells is typically defined in a way that is considered "allocentric", meaning that the representation is centered on the world/environment, rather than the agent's position/perspective.

Ego-tuning depends on the perspective of the agent (here, a rat 🐀​). In our paper, ego-tuning refers to selective increases in a neuron's firing rate when s rat's head or body is oriented in a specific way relative to a reference point in the environment. For example, a neuron increases its firing rate when a reference point is on the animal's *left hand side*.

Does that make sense?

Thanks so much to my amazing supervisors (@benjamin_dunn, @ edvardmoser and @ maybrittmoser my brilliant collaborator who collected all of the data (@ j ansigurdblack) and my co-authors (@davidt and @ va_normand) for their help along the way!

Would love to chat with anyone interested in this topic!!

12/12

Our results suggest that:

* ego-tuning in the hippocampus may have been drastically over-estimated in the past and

* that statistical approaches should always be rigorously tested!

11/12

Result: 4.5% of the cells were EB modulated, and only 2 of those cells were stably-tuned across sessions.

10/12

To mitigate these false positives, we (1) tested the cells against a null distribution that accounts for position-HD dependencies and (2) optimized the significance level to perform hypothesis testing at.

9/12

Most noteworthy was that when we increased out-of-field or place field size, the false positive rates exploded! We think this has something to do with behavioral biases within the place field 🧐

8/12

After depleting the Moser lab's compute resources (thanks IDUN), we found staggering false positive rates... Even under *ideal conditions* (e.g., cute gaussian fields, zero noise), simulated place cells were falsely classified as ego-tuned between 25-100% of the time.

7/12

To simulate these cells, we used real rat foraging behavior (86 sessions worth!)

6/12

To figure out why we couldn't see any of this tuning by eye (like the beautiful pinwheel patterns you see in RSC, postrhinal, etc.), we simulated place- and ego-tuned cells and tested them in our pipeline.

5/12

We recorded neurons from rats in the open field and found that when we used field-standard approaches, more than HALF of the cells passed the criteria for ego-tuning.

So, feature or bug? 🤔​ Our study quantifies the degree of egocentric tuning in our data vs. how much we can attribute to the rat's [biased] behavior.

✨​Big picture: The hippocampal field has been talking a lot about how place cells might be ego-tuned to points/goals in the animal's local environment (a cell goes nuts when a special reference point is to the agent’s right-hand-side)

2/12

TLDR; We only found *two* neurons in our CA1 dataset that are egocentric-modulated 👀

My first @biorxiv_neursci (and the first part of my PhD work) is live!

Link to preprint: https://www.biorxiv.org/content/10.1101/2023.11.08.566253v1?med=mas

#tweeprint

1/12

My first post on Mastodon! Hi, I'm Jo :) I'm a #neuroscience PhD student in the Moser and Dunn Groups at the Kavli Institute for Systems Neuroscience in Trondheim, Norway! I'm currently very far from home (I'm a Southern California native), but am spending the dark days doing what I love - hippocampal physiology!

I am just wrapping up the first part of my PhD work on egocentric tuning in the #hippocampus (which I will post about here soon), and have started up a second project this year looking into the coordination between hippocampus-subiculum-mec during #navigation via multi-region NPX 2.0 recordings :)

When i'm not recording ~sweet ripples~, I like to go for walks in the local forest with my border collie 🐶​

#introduction