Kari Hoffman
@karihoffman.bsky.social
neuroscientist @vanderbilt studying neural circuit+population rules for creating and deploying knowledge. computational neuroethology.
Pinned
Kari Hoffman
@karihoffman.bsky.social
· Apr 15
Experience reorganizes content-specific memory traces in macaques
Memory formation requires neural activity reorganization during experience that persists in sleep. How these processes promote learning while preserving established memories remains unclear. We record...
www.biorxiv.org
How does the brain integrate information from new experiences while preserving established memories? Have a look at our latest preprint,
"Experience reorganizes content-specific memory traces in macaques" 🧵
🧪🧠🤖👩🔬
www.biorxiv.org/content/10.1...
"Experience reorganizes content-specific memory traces in macaques" 🧵
🧪🧠🤖👩🔬
www.biorxiv.org/content/10.1...
Reposted by Kari Hoffman
Bichan Wu (@bichanw.bsky.social) & I wrote a tutorial paper on Reduced Rank Regression (RRR) — the statistical method underlying "communication subspaces" from Semedo et al 2019 — aimed at neuroscientists.
arxiv.org/abs/2512.12467
arxiv.org/abs/2512.12467
Reduced rank regression for neural communication: a tutorial for neuroscientists
Reduced rank regression (RRR) is a statistical method for finding a low-dimensional linear mapping between a set of high-dimensional inputs and outputs. In recent years, RRR has found numerous applica...
arxiv.org
December 17, 2025 at 2:06 AM
Bichan Wu (@bichanw.bsky.social) & I wrote a tutorial paper on Reduced Rank Regression (RRR) — the statistical method underlying "communication subspaces" from Semedo et al 2019 — aimed at neuroscientists.
arxiv.org/abs/2512.12467
arxiv.org/abs/2512.12467
Reposted by Kari Hoffman
let's talk in person!
but fwiw I personally think that we talk about dimensionality! to me the important ideas within the neural manifold framework are: (1) manifolds reflect biological constraints, (2) capture population-wide functions/computations, (3) manifolds (may) have ontological power
but fwiw I personally think that we talk about dimensionality! to me the important ideas within the neural manifold framework are: (1) manifolds reflect biological constraints, (2) capture population-wide functions/computations, (3) manifolds (may) have ontological power
December 13, 2025 at 5:49 PM
let's talk in person!
but fwiw I personally think that we talk about dimensionality! to me the important ideas within the neural manifold framework are: (1) manifolds reflect biological constraints, (2) capture population-wide functions/computations, (3) manifolds (may) have ontological power
but fwiw I personally think that we talk about dimensionality! to me the important ideas within the neural manifold framework are: (1) manifolds reflect biological constraints, (2) capture population-wide functions/computations, (3) manifolds (may) have ontological power
🤩 + impressive answer 🧭🚕 @ 2:50 “Trust me, knowledge is power” 💀 This is my guy.
Thanks to @cnn.com for covering our research on London taxi drivers in their new, rather chatty, format 'Creators'
Taxi driver Tom Scullion is the star of this piece. He trains others to learn the knowledge an has so many insights into that process.
#neuroskyence
www.youtube.com/watch?v=K7df...
Taxi driver Tom Scullion is the star of this piece. He trains others to learn the knowledge an has so many insights into that process.
#neuroskyence
www.youtube.com/watch?v=K7df...
December 13, 2025 at 5:00 PM
🤩 + impressive answer 🧭🚕 @ 2:50 “Trust me, knowledge is power” 💀 This is my guy.
Reposted by Kari Hoffman
Good resp to Bhattacharya, noting the agenda of The Spectator.
When we rebut Trump attacks on science it’s good to talk about his agenda and the agenda backing him—he was selected for the job by donors who want to privatize federal funding and use science as a wedge issue to get votes for thr side.
When we rebut Trump attacks on science it’s good to talk about his agenda and the agenda backing him—he was selected for the job by donors who want to privatize federal funding and use science as a wedge issue to get votes for thr side.
TBH, this piece by Jay Bhattacharya (published in The Spectator, a nasty right wing rag) and the NIH deputy director is truly one of the most vile things I've read coming from the Trump Administration
They brag about how they "cured" DEI; WTAF?
thespectator.com/topic/cured-...
They brag about how they "cured" DEI; WTAF?
thespectator.com/topic/cured-...
How we cured DEI at the National Institutes of Health
The National Institutes of Health will no longer fund research based on DEI that has diverted resources from advancing health
thespectator.com
December 13, 2025 at 2:29 PM
Good resp to Bhattacharya, noting the agenda of The Spectator.
When we rebut Trump attacks on science it’s good to talk about his agenda and the agenda backing him—he was selected for the job by donors who want to privatize federal funding and use science as a wedge issue to get votes for thr side.
When we rebut Trump attacks on science it’s good to talk about his agenda and the agenda backing him—he was selected for the job by donors who want to privatize federal funding and use science as a wedge issue to get votes for thr side.
Reposted by Kari Hoffman
www.science.org/doi/10.1126/...
damn this is so very clever!
"... we investigated how the brain categorizes stimuli that are not linearly separable in the physical world ... The sensory manifold was ... expanded into a seven-dimensional perceptual manifold..."
damn this is so very clever!
"... we investigated how the brain categorizes stimuli that are not linearly separable in the physical world ... The sensory manifold was ... expanded into a seven-dimensional perceptual manifold..."
From sensory to perceptual manifolds: The twist of neural geometry
The brain uses geometric twists to expand neural dimensionality, thus untangling perception from sensation.
www.science.org
December 13, 2025 at 9:08 AM
www.science.org/doi/10.1126/...
damn this is so very clever!
"... we investigated how the brain categorizes stimuli that are not linearly separable in the physical world ... The sensory manifold was ... expanded into a seven-dimensional perceptual manifold..."
damn this is so very clever!
"... we investigated how the brain categorizes stimuli that are not linearly separable in the physical world ... The sensory manifold was ... expanded into a seven-dimensional perceptual manifold..."
Human multipatch L2/3 functional cell types. LFG. 🧠📈🧪
🥳Excited to share our latest human multipatch paper, now out in @natneuro.nature.com
🧠 We studied the cellular and synaptic physiology of human L2–3 pyramidal neurons and identified subtype-specific local connectivity rules across individuals.
www.nature.com/articles/s41...
Join us: penglab.de
🧠 We studied the cellular and synaptic physiology of human L2–3 pyramidal neurons and identified subtype-specific local connectivity rules across individuals.
www.nature.com/articles/s41...
Join us: penglab.de
December 13, 2025 at 1:31 PM
Human multipatch L2/3 functional cell types. LFG. 🧠📈🧪
Reposted by Kari Hoffman
Tolerance has gone too far. Researchers should date other people, in my opinion
Researchers have dated vertebrae from a massive prehistoric shark thought to have ruled the waves off northern Australia back to further in the Cretaceous period than was previously known.
Before megalodon, researchers say a monstrous shark ruled ancient Australian seas
Researchers have dated vertebrae from a massive prehistoric shark thought to have ruled the waves off northern Australia back to further in the Cretaceous period than was previously known.
bit.ly
December 13, 2025 at 11:49 AM
Tolerance has gone too far. Researchers should date other people, in my opinion
Reposted by Kari Hoffman
Last day to register for the 50th anniversary meeting Jan 8-11: parkcitywinterconf.org/register/
Historical perspectives from Lynn Nadel, Os Steward, Jim McClelland, and topics from synaptic plasticity to neural circuit dynamics of learning and memory systems to aging and dementia. #neuroskyence
Historical perspectives from Lynn Nadel, Os Steward, Jim McClelland, and topics from synaptic plasticity to neural circuit dynamics of learning and memory systems to aging and dementia. #neuroskyence
December 12, 2025 at 2:58 PM
Last day to register for the 50th anniversary meeting Jan 8-11: parkcitywinterconf.org/register/
Historical perspectives from Lynn Nadel, Os Steward, Jim McClelland, and topics from synaptic plasticity to neural circuit dynamics of learning and memory systems to aging and dementia. #neuroskyence
Historical perspectives from Lynn Nadel, Os Steward, Jim McClelland, and topics from synaptic plasticity to neural circuit dynamics of learning and memory systems to aging and dementia. #neuroskyence
Nice thread (and nice recognition for @trackingactions.bsky.social!)
I regard what I/we do as impt for humanity (not vanity), and I spend a lot of time mapping out how to get to those end goals efficiently (like in this recent book). Unfortunately, I don't see paths to better treatments that don't involve animal research.
press.princeton.edu/books/hardco...
press.princeton.edu/books/hardco...
Elusive Cures
A neuroscientist’s bold proposal for tackling one of the greatest challenges of our time—brain and mental illnesses
press.princeton.edu
December 12, 2025 at 2:43 PM
Nice thread (and nice recognition for @trackingactions.bsky.social!)
Reposted by Kari Hoffman
We give examples for less striking number of neurons here. For different species, tasks, and brain areas, it's always the same observation: PCA overestimates the dimensionality -except for one very simple task- and this overestimate gets worse w the number of neurons
www.biorxiv.org/content/10.1...
www.biorxiv.org/content/10.1...
Nonlinear manifolds underlie neural population activity during behaviour
There is rich variety in the activity of single neurons recorded during behaviour. Yet, these diverse single neuron responses can be well described by relatively few patterns of neural co-modulation. ...
www.biorxiv.org
December 12, 2025 at 12:51 AM
We give examples for less striking number of neurons here. For different species, tasks, and brain areas, it's always the same observation: PCA overestimates the dimensionality -except for one very simple task- and this overestimate gets worse w the number of neurons
www.biorxiv.org/content/10.1...
www.biorxiv.org/content/10.1...
📣Register now for the 50th Anniversary Park City Winter Conference on the Neurobiology of Learning and Memory parkcitywinterconf.org/register/
Deadline tomorrow, Friday, the 12th! Spread the word. 🧠🔬👩🔬
➡️Top 5 reasons to attend:
1/6
Deadline tomorrow, Friday, the 12th! Spread the word. 🧠🔬👩🔬
➡️Top 5 reasons to attend:
1/6
December 11, 2025 at 5:07 PM
📣Register now for the 50th Anniversary Park City Winter Conference on the Neurobiology of Learning and Memory parkcitywinterconf.org/register/
Deadline tomorrow, Friday, the 12th! Spread the word. 🧠🔬👩🔬
➡️Top 5 reasons to attend:
1/6
Deadline tomorrow, Friday, the 12th! Spread the word. 🧠🔬👩🔬
➡️Top 5 reasons to attend:
1/6
correction: he *is* reviewer #3
Met an old pal at #SfN25, he's still waiting to hear back from reviewer #3
November 22, 2025 at 3:30 PM
correction: he *is* reviewer #3
Reposted by Kari Hoffman
Keep in mind, we could have already advanced so much in this field if, for political reasons, mRNA vaccines were not severely attacked over the past 5 years. We are closer than ever to a cure for #MultipleSclerosis, and that involves preventing #EBV from damaging the brain.
Common virus jab could be key in fight against multiple sclerosis
The vaccine will be trialled in patients recently diagnosed with MS
www.independent.co.uk
November 22, 2025 at 2:42 PM
Keep in mind, we could have already advanced so much in this field if, for political reasons, mRNA vaccines were not severely attacked over the past 5 years. We are closer than ever to a cure for #MultipleSclerosis, and that involves preventing #EBV from damaging the brain.
Reposted by Kari Hoffman
🚨New publication!
I am extremely happy to share this new review article in elife on #Traveling_Waves!
@erc.europa.eu
@upcite.bsky.social
elifesciences.org/articles/106...
I am extremely happy to share this new review article in elife on #Traveling_Waves!
@erc.europa.eu
@upcite.bsky.social
elifesciences.org/articles/106...
Traveling waves across scales: Different mechanisms but same canonical computation?
The review proposes a novel mechanistic distinction between first- and second-order traveling waves that subserves a same canonical computation by ordering neuronal processing to impose a computationa...
elifesciences.org
November 19, 2025 at 3:54 PM
🚨New publication!
I am extremely happy to share this new review article in elife on #Traveling_Waves!
@erc.europa.eu
@upcite.bsky.social
elifesciences.org/articles/106...
I am extremely happy to share this new review article in elife on #Traveling_Waves!
@erc.europa.eu
@upcite.bsky.social
elifesciences.org/articles/106...
Reposted by Kari Hoffman
I wrote this last week with the news of the shutdown deal, about why we need a lot more to save US science. Comments and questions are welcome.
-------------------
As a US scientist and NIH employee, I had mixed feelings about the reopening of the US government this week. 1/
-------------------
As a US scientist and NIH employee, I had mixed feelings about the reopening of the US government this week. 1/
November 19, 2025 at 12:35 PM
I wrote this last week with the news of the shutdown deal, about why we need a lot more to save US science. Comments and questions are welcome.
-------------------
As a US scientist and NIH employee, I had mixed feelings about the reopening of the US government this week. 1/
-------------------
As a US scientist and NIH employee, I had mixed feelings about the reopening of the US government this week. 1/
Happening now ss3 ss4 dentate spikes, beta, category learning in freely moving 🐒
November 17, 2025 at 4:43 PM
Happening now ss3 ss4 dentate spikes, beta, category learning in freely moving 🐒
Reposted by Kari Hoffman
For those coming to SfN, I’ll be giving a talk showing evidence of hippocampal neuronal replay 🎞️🔁 in HUMANS as part of the “Representation of Time in the Brain” minisymposium (Wednesday morning)
Our stellar group of speakers also wrote a preview of the session in @sfnjournals.bsky.social #sfn2025
🧠
Our stellar group of speakers also wrote a preview of the session in @sfnjournals.bsky.social #sfn2025
🧠
Neural Representation of Episodic Time
Inspired by recent discoveries of neural populations that track time for specific moments (time cells) and elapsed durations (temporal context and periodic time cells), this review, based on a minisym...
www.jneurosci.org
November 15, 2025 at 7:15 PM
For those coming to SfN, I’ll be giving a talk showing evidence of hippocampal neuronal replay 🎞️🔁 in HUMANS as part of the “Representation of Time in the Brain” minisymposium (Wednesday morning)
Our stellar group of speakers also wrote a preview of the session in @sfnjournals.bsky.social #sfn2025
🧠
Our stellar group of speakers also wrote a preview of the session in @sfnjournals.bsky.social #sfn2025
🧠
Reposted by Kari Hoffman
November 16, 2025 at 6:24 PM
Reposted by Kari Hoffman
Sad to miss the rest of this session, but excited to go meet with the brainfacts.org team. We have a lot of exciting new results in brain/mind research to unpack (yeah!) as well as a disturbing amount to misinformation to combat (sigh). If you aren’t following @brainfacts.org, you must!
BrainFacts
brainfacts.org
November 16, 2025 at 4:59 PM
Sad to miss the rest of this session, but excited to go meet with the brainfacts.org team. We have a lot of exciting new results in brain/mind research to unpack (yeah!) as well as a disturbing amount to misinformation to combat (sigh). If you aren’t following @brainfacts.org, you must!
Reposted by Kari Hoffman
Come hear about state-driven neural complexity today #SfN25
PP13 - "Deep cortical layer stimulation reveals state-dependent changes in neural excitability"
Poster Session 1-5 pm
Computational Approaches & Experimental Analyses I
PP13 - "Deep cortical layer stimulation reveals state-dependent changes in neural excitability"
Poster Session 1-5 pm
Computational Approaches & Experimental Analyses I
a man in a star trek uniform is sitting in front of a control panel
ALT: a man in a star trek uniform is sitting in front of a control panel
media.tenor.com
November 16, 2025 at 3:13 PM
Come hear about state-driven neural complexity today #SfN25
PP13 - "Deep cortical layer stimulation reveals state-dependent changes in neural excitability"
Poster Session 1-5 pm
Computational Approaches & Experimental Analyses I
PP13 - "Deep cortical layer stimulation reveals state-dependent changes in neural excitability"
Poster Session 1-5 pm
Computational Approaches & Experimental Analyses I
Reposted by Kari Hoffman
🧬 Evolution meets neuroscience at #SfN25!
Learn how multi-omics approaches are revealing how evolution acts on cell types, underpinning neural circuitry and behavior changes across diverse species.
📅 Tues., 11/18, 9:30am–12:00pm
📍 Rm 6CF
📲 https://www.abstractsonline.com/pp8/#!/21171/session/1213
Learn how multi-omics approaches are revealing how evolution acts on cell types, underpinning neural circuitry and behavior changes across diverse species.
📅 Tues., 11/18, 9:30am–12:00pm
📍 Rm 6CF
📲 https://www.abstractsonline.com/pp8/#!/21171/session/1213
November 15, 2025 at 10:50 PM
🧬 Evolution meets neuroscience at #SfN25!
Learn how multi-omics approaches are revealing how evolution acts on cell types, underpinning neural circuitry and behavior changes across diverse species.
📅 Tues., 11/18, 9:30am–12:00pm
📍 Rm 6CF
📲 https://www.abstractsonline.com/pp8/#!/21171/session/1213
Learn how multi-omics approaches are revealing how evolution acts on cell types, underpinning neural circuitry and behavior changes across diverse species.
📅 Tues., 11/18, 9:30am–12:00pm
📍 Rm 6CF
📲 https://www.abstractsonline.com/pp8/#!/21171/session/1213
Reposted by Kari Hoffman
And I’m a big fan of Turing, von Neumann, Shannon, Metcalfe, Hinton, Sejnowski, and all the other algorithmic and computation people. No shade.
But data limits still limit understanding of the brain. That’s why the #NIH US BRAIN Init was so important: public investment made new tools.
But data limits still limit understanding of the brain. That’s why the #NIH US BRAIN Init was so important: public investment made new tools.
November 15, 2025 at 5:33 PM
And I’m a big fan of Turing, von Neumann, Shannon, Metcalfe, Hinton, Sejnowski, and all the other algorithmic and computation people. No shade.
But data limits still limit understanding of the brain. That’s why the #NIH US BRAIN Init was so important: public investment made new tools.
But data limits still limit understanding of the brain. That’s why the #NIH US BRAIN Init was so important: public investment made new tools.