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Miriam Janssen

@mimijanssen.bsky.social

36 followers 70 following 10 posts

Grad researcher in the MVDM lab @Dartmouth studying value learning and memory | NSF grfp & E.E. Just grad fellow 🐭🐵🤖

Posts Replies Media

Reposted by Miriam Janssen

Tommaso Patriarchi @tpatriarchi.bsky.social · 27/03/2026

Wait… localized norepinephrine transients in the awake visual cortex?! Who would have guessed this neuromodulatory signal is that spatially precise, right where visual processing is happening. Brain state control just got a lot more local. @ruedigersarah.bsky.social www.nature.com/articles/s41...

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Reposted by Miriam Janssen

Ben Saunders @bensaunders.bsky.social · 09/03/2026

Check out our latest research drop! We show BLA dopamine signaling encodes the emotional weight of sensory transitions, but not the associative strength or value of stimuli. These signals dynamically rescale when the learning context changes: "this matters most!" www.biorxiv.org/content/10.1...

biorxiv.org

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Miriam Janssen @mimijanssen.bsky.social · 04/08/2025

We are excited about the next steps, such as determining causality and the circuit mechanisms of SWR-DA coupling, as well as whether replay content of different valences is evaluated differently. :) (9/9)

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Miriam Janssen @mimijanssen.bsky.social · 04/08/2025

Building on earlier findings (Gomperts et al., 2015), our work shows that DAergic transients known to drive learning in response to online experienced events are also present following offline replayed events. (8/9)

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Miriam Janssen @mimijanssen.bsky.social · 04/08/2025

To characterize the SWR-DA, we fit LMMs. We found that the SWR-DA size could not be explained by the differences in track running speed (a proxy for motivation) or by the magnitude of the prediction error coding during the task. (7/9)

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Miriam Janssen @mimijanssen.bsky.social · 04/08/2025

Averaging across all sessions and mice, we found an increase in DA peaking ~0.3 s after SWRs! The SWR-DA transient was about 24% of the size of a putative positive RPE. (6/9)

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Miriam Janssen @mimijanssen.bsky.social · 04/08/2025

Next, during a rest period before or after the task, we found SWR-triggered DA transients (SWR-DA). Here are some examples from three different sessions and mice (MUA: black tick marks; local field potential traces: blue line; GRABDA2m fiber photometry traces: green line). (5/9)

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Miriam Janssen @mimijanssen.bsky.social · 04/08/2025

Consistent with previous work, we found a clear suppression of the dopamine concentration ([DA]) signal following reward omission relative to the expected (medium) amount, and a clear increase in [DA] following larger-than-expected reward. (4/9)

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Miriam Janssen @mimijanssen.bsky.social · 04/08/2025

First, we established what putative VS DA prediction errors look like in our hands by measuring the GRAB-DA signal on a probabilistic reward task. Mice ran on a linear track where rewards of different sizes were delivered at both ends. (3/9)

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Miriam Janssen @mimijanssen.bsky.social · 04/08/2025

Leading computational theories (e.g. Mattar & Daw, 2018) suggest that replayed experiences drive learning via a teaching signal (e.g.prediction errors). To test if this may be true within the brain, we investigated the link between putative dCA1 replay events (SWRs) and VS DA teaching signals. (2/9)

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Miriam Janssen @mimijanssen.bsky.social · 04/08/2025

Hung-tu Chen, Nicolas Tritsch, Matt van der Meer, and I have submitted a new preprint (doi.org/10.1101/2025...) in which we use simultaneous hippocampal ephys and ventral striatal (VS) fiber photometry to establish a link between sharp-wave ripples (SWRs) and VS dopamine (DA) in mice. (1/9)

biorxiv.org

Ventral Striatal Dopamine Increases following Hippocampal Sharp-Wave Ripples

Leading theories suggest that hippocampal replay drives offline learning through coupling with an internal teaching signal such as ventral striatal dopamine (DA); however, the relationship between hip...

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Miriam Janssen @mimijanssen.bsky.social · 21/06/2025

First op-ed on why science funding matters! www.unionleader.com/opinion/op-e...

unionleader.com

Miriam Janssen: 1% of your tax dollar goes to science

APPROXIMATELY 1% of your tax dollars are used to fund science research. The Trump administration is cutting roughly 40 to 50% percent of this research funding — what does that

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Reposted by Miriam Janssen

Matthijs van der Meer @mvandermeer.bsky.social · 30/05/2025

We are looking for a research assistant/lab manager to join the lab! A supportive, collaborative environment where you can learn neural recording with Neuropixels, optogenetics, fiber photometry, and neural data analysis.

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