Hafting-Fyhn Lab

Grid cells accurately track movement during path integration-based navigation despite switching reference frames - Nature Neuroscience Grid cells do not maintain a stable pattern during a self-motion-based task, but track animal movement in multiple local reference frames and reanchor to task-relevant objects, thus estimating local r...

No GPS in the head? Path integration by entorhinal grid cells without the grid pattern. Interesting paper from Heidelberg. www.nature.com/articles/s41...

Local inhibitory circuits mediate cortical reactivations and memory consolidation Reducing inhibitory activity after training prevents cortical reactivations and memory consolidation.

New paper out with @hafting.bsky.social and @markandermann.bsky.social lab on reactivations and memory consolidation : www.science.org/doi/10.1126/...

Great talk by David Olson UCDavis yesterday at UCSD. Impressive voyage through drug discovery, chemistry and systems neuroscience. www.science.org/doi/10.1126/...

Harvard today, your institution tomorrow.

It's all part of the Project 2025 plan to destroy high education in America.

All leading US universities depend on federal funding and tuition dollars from international students. They severely curtailed the former. Now they're eliminating the latter.

We have recently done a similar experiment but in a spatial setting (VR) and see very different properties emerging across learning, stay tuned! Special kudos to our PhD student Ingeborg Nymoen who performed most of the experiments.

5/6: The responses are anatomically separated in MEC (but not in POR).

4/6: While POR neurons respond to cues and cue-outcome associations - only a few MEC neurons develop visual cue selectivity, but large populations develop a bias towards the reward or the cue-reward association

3/6: A large fraction of POR neurons are visual cue-responsive from the beginning as mice begin to learn the task, while MEC neurons develop responses especially to the plus cue during learning.

2/6: We compare the neural dynamics in postrhinal (POR) and medical entorhinal cortex (MEC) as mice learn a visual Go/NoGo task. Same cells recorded from completely naïve to expert and through rule reversal.

New preprint out in eLife! Neurons in medical entorhinal cortex (MEC) develop responses to visual cues and reward as mice learn a visual Go/NoGo task. elifesciences.org/reviewed-pre...

Goal-specific hippocampal inhibition gates learning - Nature Parvalbumin-positive interneurons in the hippocampal CA3 substantially reduce firing on approach to and at goal locations while food-deprived mice learn to find food.

Check out the full paper here: www.nature.com/articles/s41...

In contrast, AAV-mediated ACAN knockout in adult mice increased ocular dominance plasticity. Moreover, in vivo Chondroitinase ABC treatment of KO mice resulted in reduced firing rate of PV+ cells. Suggesting that compensatory mechanisms may be activated in response to the germline loss of aggrecan.

We established both a germline knockout (KO) mouse model (ACANflx/PVcre) and an adeno-associated virus to eliminate aggrecan production from PV+ neurons. Surprisingly, electrophysiological properties of PV+ interneurons and ocular dominance plasticity of adult KO mice were similar to controls.

Differential impacts of germline and adult aggrecan knockout in PV+ neurons on perineuronal nets and PV+ neuronal function - Molecular Psychiatry Molecular Psychiatry - Differential impacts of germline and adult aggrecan knockout in PV+ neurons on perineuronal nets and PV+ neuronal function

Knockout of aggrecan in PV+ interneurons eliminate the expression of PNNs labeled by WFA. KO animals showed similar long-term memory as controls, but showed lower level of anxiety-related behavior in an open field and zero maze. www.nature.com/articles/s41...

People who can’t picture images in their ‘mind’s eye’ still represent them in their brains Imaging study of people with aphantasia reveals differences—but not a complete deficit—in visual processing area

Fascinating new study: The visual cortex in people (like me!! 👋) with #aphantasia processes visual info but doesn’t translate it into conscious images. This disconnect explains why they can “know” details (like layouts) without “seeing” them—mental pictures don’t fully form. (Can confirm!)

Strikingly different responses to visual stimuli in postrhinal (POR) cortex compared to MEC. Following the same neurons through the learning process. Single cell example from each region below.

Task and Behavior-Related Variables Are Encoded by the Postrhinal and Medial Entorhinal Cortex During Non-Spatial Associative Learning The medial entorhinal cortex (MEC) is pivotal in spatial computations and episodic memory. In particular, an animal’s position can be decoded from the activity of entorhinal grid cells. However, it re...

In this preprint we see how activity in entorhinal cortex change during learning a non-spatial visual association task. Neurons in the MEC initially exhibited weak responses to visual cues but gradually developed strong tuning toward the rewarded trials. doi.org/10.1101/2024...

Running on Fumes: An Analysis of Fine Particulate Matter’s Impact on Finish Times in Nine Major US Marathons, 2003–2019 - Sports Medicine Background Under controlled conditions and in some observational studies of runners, airborne fine particulate matter smaller than 2.5 microns in diameter (PM2.5) is associated with exercise performan...

Interesting study indicating that even a bit of air pollution (PM2.5) slow down marathon performance. Average Chicago Marathon times 8 minutes faster in a low-pollution year 2019 (~3 micrograms/cubic meter) than in a high-pollution year (~20 mi-g/m3). link.springer.com/article/10.1...

A graph showing life expectancy (vertical axis) compared to health expenditures per capita (horizontal access) for more than a dozen countries. The USA stands alone way off to the right (expensive) and not nearly as high as any of the others (lower life expectancy).

I wish more people were literate enough to truly be able to read & understand this graph, and to be upset by it. Because it's upsetting! We pay SO MUCH MORE for healthcare, and have worse outcomes & lower life-expectancy. The data is clear: We are coming in last in the race for health & well-being.

Deciphering the Role of Aggrecan in Parvalbumin Interneurons: Unexpected Outcomes from a Conditional ACAN Knockout That Eliminates WFA+ Perineuronal Nets The transition from juvenile to adult is accompanied by the maturation of inhibitory parvalbumin-positive (PV+) neurons and reduced plasticity. This transition involves the formation of perineuronal n...

BioRxiv: Knockout of ACAN in PV+ cells inhibit formation of WFA positiv perineuronal nets (PNNs) around PV+ cells. ACAN KO mice show lower level of anxiety-related behavior. In the morris watermaze they employ bolder search strategy, but long-term memory is the same. doi.org/10.1101/2024...

A population code for spatial representation in the zebrafish telencephalon - Nature Using a tracking microscope for freely moving animals, the authors discover a population of place cells in the zebrafish brain and demonstrate that a non-amniote brain is capable of integrating alloth...

Finally, recording from freely swimming larval zebrafish reveals place code. I wonder how it is in salmon returning to their natal creek. www.nature.com/articles/s41...

Cortical Reactivations Modulated by Local Inhibitory Circuits Mediate Memory Consolidation Highly salient events activate neurons across various brain regions. During subsequent rest or sleep, the activity patterns of these neurons often correlate with those observed during the preceding ex...

www.biorxiv.org/content/10.1...

We find that reduction of PV+ neuron activity in offline periods after learning selectively attenuates reactivations and learning, with no apparent effects on normal function during training.

New preprint together with the Andermann lab– Cortical reactivations modulated by local inhibitory circuits mediate memory consolidation biorxiv.org/content/10.110…

FENS Regional Meeting 2025 Welcome to the FENS Regional Meeting 2025 — in Oslo, Norway.

Welcome to Neuroscience meeting in Oslo, Norway. June 2025 #fens #uio #unioslo frm2025oslo.no