Raaj Gowrishankar

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...

I am totally pumped about this new work . "Task-trained RNNs" are a powerful and influential framework in neuroscience, but have lacked a firm theoretical footing. This work provides one, and makes direct contact with the classical theory of random RNNs:
www.biorxiv.org/content/10.6...

New preprint out!
In this study, we introduce NanoFLex, a strategy that combines #HaloTag variants with #nanobodies -based immunolabeling to enable rapid, OneStep-IF #lifetime #multiplexing. Possible due to SmartSecondaries fused to #HaloTag from @nanotag.bsky.social: www.biorxiv.org/content/10.6...

A neuromodulatory circuit-to-molecular pathway for reformatting aversive memories during recall Tan et al. identify a neuromodulatory circuit-to-molecular pathway in rats that updates aversive memories when they are recalled. Noradrenaline from the locus coeruleus triggers synapse-to-nuclear tra...

Excited to share our new paper:
We uncover a locus coeruleus→amygdala circuit linking β-adrenergic signaling to transcription regulation in defined amygdala cells during memory reconsolidation—+ stress or elevated noradrenergic signaling at recall can strengthen memory.
www.cell.com/neuron/abstr...

Combined assembloid modeling and 3D whole-organ mapping captures the microanatomy and function of the human fallopian tube Tunable assembloid modeling and CODA tissue mapping, in tandem, design a tissue-validated in vitro model of the fallopian tube.

I think there is a need for a complete re-think for organoid modeling.

As long as the architecture of organoids that you produce is not directly compared to a 3D map of the organ (say, a fallopian tube) or disease to be modeled, it will be approximate.

More here: www.science.org/doi/full/10....

Photo of Dr. Zachary Pennington and Dr. Milan Valyear

We're thrilled to welcome Dr. @zachtpennington.bsky.social and Dr. @milanium.bsky.social as Assistant Professors in our Behavioural Neuroscience area and members of the @dmcbrainhealth.bsky.social.

Read their Q&As: psych.ubc.ca/news

Place cells in CA1 lack topographical organization of firing locations | PNAS Topography is a well-described and well-known concept for cortical organization in primary sensory and motor cortices of mammalian brains. Similar ...

A half-century old question may have its final answer. Using high-resolution #Mini2P microscopes, we find no evidence of local topography in #PlaceCells. Place fields of neighbouring cells are no more similar than those of randomly selected cells. 🧠🗺️ Out now in @pnas.org www.pnas.org/doi/10.1073/...

Applications for our Next Generation Leaders program are open!

For 3 years, accepted early career scientists will join a supportive network and contribute to our research initiatives.

Apply by Mar. 31: https://bit.ly/3OjzdRa

📸 Photo by NGL Alum @bjmarlin.bsky.social

🔬🧠 Releasing the 1.0 version of #Suite2p and THE PAPER w/ @marius10p.bsky.social! Now with GPU acceleration. Want to use Suite2p but don’t have 100,000 neuron recordings? We show you how to get those with a standard 2p microscope #neuroscience #imaging #neuroAI www.biorxiv.org/content/10.6...

Duration between rewards controls the rate of behavioral and dopaminergic learning - Nature Neuroscience Cue–reward learning rate scales proportionally with the time between rewards. Consequently, learning over a fixed duration is independent of the number of trials. This challenges trial-based dopamine ...

Very excited to post our paper led by @daburke.bsky.social www.nature.com/articles/s41... where we uncover a simple mathematical rule underlying how brains learn that a cue predicts a reward. 1/26

Astrocytes enable amygdala neural representations supporting memory - Nature Astrocytes in the basolateral amygdala dynamically track fear state and support fear memory retrieval and extinction.

Nice work from my long time collaborator and pal Andrew Holmes' lab, led by the amazing Olena Bukalo.

www.nature.com/articles/s41...

Happy to share the newest study from our lab, led by superstar postdoc Dr. Rodrigo Campos Cardoso, where we resolve the infralimbic cortex GABAergic circuits of fear extinction: tinyurl.com/38vvr2my

Same task, different strategy ↔️

Why do identical neural network models develop separate internal approaches to solve the same problem?

@annhuang42.bsky.social explores the factors driving variability in task-trained networks in our latest @kempnerinstitute.bsky.social Deeper Learning blog.

Oligodendrocyte mechanotransduction channel TMEM63A regulates myelin sheath geometry Dereddi, Djannatian, and colleagues show that oligodendrocytes use mechanical cues to measure axon size. The stretch-activated channel TMEM63A converts membrane tension into calcium signals, which cal...

We identified how mechanical forces shape myelin development. The TMEM63A channel in oligodendrocytes converts physical cues into molecular signals that control myelin growth.

Oligodendrocyte mechanotransduction channel TMEM63A regulates myelin sheath geometry: Neuron www.cell.com/neuron/fullt...

BG GRC Oath: I acknowledge that the go/no-go model of the BG was useful but it is outdated and incorrect, or at least incomplete. I pledge not to use the go/no-go model as a strawman to motivate my work.

Taking the #GRCBasalGanglia Oath ✋🏼

I acknowledge that the go/no-go model of the BG was useful but it is outdated and incorrect, or at least incomplete. I pledge not to use the go/no-go model as a strawman to motivate my work.

Our latest preprint. More evidence that diabetic neuropathy is a neuro degenerative disease. Very proud of @ish1789.bsky.social and our whole PRECISION group who made this work possible. #HEALinitiative funded

Corticosterone accelerates behavioral inflexibility via plasticity-related gene expression in the dorsal striatum Neuropsychopharmacology - Corticosterone accelerates behavioral inflexibility via plasticity-related gene expression in the dorsal striatum

Chronic corticosterone shifts behavior from flexible to inflexible by differentially regulating striatal plasticity genes:

Cort ⬇️ plasticity gene expression in the dorsomedial striatum & ⬆️ plasticity programs in the dorsolateral striatum

speaker: any questions

me in my mind: yes how did you get funding for this

This Research Highlight discusses findings showing that heavy alcohol use decreases BDNF in the ventrolateral orbitofrontal cortex (vlOFC) of mice & that increased BDNF in the vlOFC–dorsolateral striatum pathway decreases alcohol intake, seeking & relapse

A prefrontal cortex map based on single-neuron activity - Nature Neuroscience The authors mapped spontaneous and choice activity across mouse prefrontal cortex. The activity maps aligned with intrinsic connectivity rather than anatomical subregions, suggesting that connectivity...

Main postdoc study out! We can redefine prefrontal cortex regions with single-unit activity! Grateful to @carlenlab.bsky.social and @weltgeischt.bsky.social who made this crazy project real. Thanks to all co-authors, collaborators, and reviewers.
www.nature.com/articles/s41...

🥳🥳🥳 Pretty fab start to 2026!!

Different learning algorithms achieve shared optimal outcomes in humans, rats, and mice Animals must exploit environmental regularities to make adaptive decisions, yet the learning algorithms that enabels this flexibility remain unclear. A central question across neuroscience, cognitive science, and machine learning, is whether learning relies on generative or discriminative strategies. Generative learners build internal models the sensory world itself, capturing its statistical structure; discriminative learners map stimuli directly onto choices, ignoring input statistics. These strategies rely on fundamentally different internal representations and entail distinct computational trade-offs: generative learning supports flexible generalisation and transfer, whereas discriminative learning is efficient but task-specific. We compared humans, rats, and mice performing the same auditory categorisation task, where category boundaries and rewards were fixed but sensory statistics varied. All species adapted their behaviour near-optimally, consistent with a normative observer constrained by sensory and decision noise. Yet their underlying algorithms diverged: humans predominantly relied on generative representations, mice on discriminative boundary-tracking, and rats spanned both regimes. Crucially, end-point performance concealed these differences, only learning trajectories and trial-to-trial updates revealed the divergence. These results show that similar near-optimal behaviour can mask fundamentally different internal representations, establishing a comparative framework for uncovering the hidden strategies that support statistical learning. ### Competing Interest Statement The authors have declared no competing interest. Wellcome Trust, https://ror.org/029chgv08, 219880/Z/19/Z, 225438/Z/22/Z, 219627/Z/19/Z Gatsby Charitable Foundation, GAT3755 UK Research and Innovation, https://ror.org/001aqnf71, EP/Z000599/1

paper🚨
When we learn a category, do we learn the structure of the world, or just where to draw the line? In a cross-species study, we show that humans, rats & mice adapt optimally to changing sensory statistics, yet rely on fundamentally different learning algorithms.
www.biorxiv.org/content/10.1...

Congratulations to Corinna, Justin, you and the team!🙌🏽

🧠⚡️💊New @nature.com publication !

Mimicking opioid analgesia in cortical pain circuits

We built a brain-behavior framework to decode spontaneous chronic pain in mice—and to biologically mimic morphine with a synthetic opioid gene therapy

nature.com/articles/s41...

@pennmedicine.bsky.social

Keri Martinowich, Ph.D., Chief Scientific Officer | The Lieber Institute for Brain Development | Research & Discovery Lieber Institute for Brain Development Appoints Keri Martinowich, Ph.D., as Chief Scientific Officer Baltimore, MD (January 6, 2025) — The Lieber Institute for Brain Development (LIBD) announced the a...

Honored to be appointed Chief Scientific Officer @lieberinstitute.bsky.social. LIBD is a uniquely collaborative place with extraordinary biological resources and a commitment to translation 🧠🔬🧪. Grateful to my colleagues and excited to help guide our next chapter!
www.libd.org/keri-martino...

Congratulations, Keri!

What is the computational role of dendritic excitations? Byung Hun Lee and team mapped voltage dynamics throughout the dendritic trees of CA1 pyramidal neurons in mice navigating in virtual reality. www.biorxiv.org/content/10.6...

Striatal and hippocampal contributions to value-based learning in adolescence Neuropsychopharmacology - Striatal and hippocampal contributions to value-based learning in adolescence

Interactions between striatal–prefrontal & hippocampal–prefrontal systems shape value-based learning & goal-directed behavior during adolescence; asynchronous maturation of these circuits may contribute to vulnerability to mental health disorders

Examining the Three‐Dimensional Spatial Architecture of Mouse Amygdala Engram Ensembles Memories are stored in a sparse population of neurons active at the time of an event, an engram ensemble, and reactivation of the engram ensemble drives memory recall. Although the amygdala is essent...

New Year, new paper from our lab. Emily Kramer used 3D light-sheet imaging and tissue clearing to examine the spatial architecture of mouse amygdala engram ensembles.

onlinelibrary.wiley.com/doi/10.1002/...

Finally, we’ve solved a long-standing mystery: what tintinnid shells are actually made of:
A new class of biomaterial formed by remarkable structural proteins unique to tintinnids.
A major milestone after 3 years of work! Read about it in our preprint: doi.org/10.64898/202...
#ProtistsOnSky