Jan Siemens

It was great having you all there! Excellent discussions and fun! I hope all of you made it home safely.

What a great Titisee Conference! “Warm, cold, and life” brought together brilliant minds exploring how temperature shapes the brain, physiology, and behaviour — from mice, wild animals to humans. Thanks to Boehringer Ingelheim Fonds for the support!

How does temperature interact with the brain? This coming Wednesday Eve Marder, Laura Duvall and I will talk about thermally-induced neural activity, plasticity and the like.

Thank you Alexander -- yes, temperature science allows for easy wordplays

Summary: Different TRP channels shape how warmth is sensed: Trpv1 helps detect fast changes, Trpm2 supports stable warm preference. Curious to hear your thoughts.

We modeled mouse behavior with a drift-diffusion model: Trpv1-KO mice have less fidelity in detecting warm temp differences but compensate with higher sampling rate leading to an overall preference similar to wildtype mice. Trpm2-KOs fail to accumulate temp evidence, losing 31°C preference.

In agreement with this idea: in mice overexpressing Trpv1, neurons respond to warmth faster—and in the behavior assay the mice quickly lock onto 31°C, switching rooms less than wildtypes (purple: Trpv1 overexpressor mice; grey wildtypes).

Calcium imaging of cultured neurons reveals Trpv1 mediates the rapid neuronal response to warming, and less the steady-state signal. This suggests that the rate of temperature increase might be encoded by Trpv1 (each triangle is the responds onset to the warmth stimulus; x-axis: time in seconds)

Tracking data shows Trpv1-KOs switch rooms more often—possibly compensating for difficulty sensing warmth.. (Yellow = TRPV1 KO mice)

Trpv1-KO mice behave similar to wildtypes overall, but show trouble deciding early on (see above) —suggesting a delay in detecting the warmth difference.

Trpm2-KO mice no longer prefer 31°C and spend equal time at 34–38°C, suggesting Trpm2 is key for selecting innocuous warm temps.

Compared to floor-only tests, the chamber assay better detects subtle warm temp differences. Mice prefer temps nearer their thermoneutral zone (~31°C). Pink = chamber; black = classic plate assay.

So we built a chamber-based assay where we can precisely control full-room temps (including floor) via Peltier elements. Mice choose between two rooms via a tunnel (but don’t linger there!).

Ambient temperature is a whole-body experience —but most tests only use heated floors, mainly probing paw/snout sensitivity. These setups might also alter room temp unpredictably, which is rarely measured/reported.

Diverging roles of TRPV1 and TRPM2 in warm-temperature detection - PubMed The perception of innocuous temperatures is crucial for thermoregulation. The TRP ion channels TRPV1 and TRPM2 have been implicated in warmth detection, yet their precise roles remain unclear. A key c...

How do mice decide which ambient temperature they prefer? Our new eLife paper by Muad (@hummuscience.bsky.social) explores how TRPV1 and TRPM2 channels shape temperature preference. A quick breakdown 👇
🔗 pubmed.ncbi.nlm.nih.gov/40215103/

Nobel laureate: I owe America my success. Today, its scientific future is in danger | CNN Dr. Ardem Patapoutian says he watches “with deep sadness as the United States’ remarkable scientific enterprise, which took generations of hard work and national investment to build, faces a concerted...

Amid the Trump admin's dismantling of the US scientific ecosystem, Nobel Prize-winner @ardemp.bskyverified.social writes on @cnn.com: "I’ve already been approached with an offer to relocate my lab to China, complete with a promise of 20 years of stable research funding." www.cnn.com/2025/04/09/h...

This was a great meeting to mix and mingle with scientists of diverse fields broadly interested in how long-term environmental changes modulate neurobiology - thank you @kavlifoundation.bsky.social‬ and @alleninstitute.bsky.social !

Metabolic tuning facilitates nociceptor resilience to excitotoxicity The capsaicin receptor, TRPV1, mediates the detection of harmful chemical and thermal stimuli. Overactivation of TRPV1 can lead to cellular damage or death through excitotoxicity, a phenomenon associa...

Very interesting study by Lin Yuan & Co in the Julius lab, explaining how sensory neurons can adapt to exitotoxicity and calcium challenges e.g. by Trpv1 activation. Spoiler alert: the electron transport chain is involved - we enjoyed discussing it in Journal club.

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

Interview mit Bodo Ramelow, Linke, Ex-Ministerpräsident Thüringen, zur Wahl

Bodo Ramelow übt sehr nachvollziehbare Kritik auch an der Rolle der Medien beim Wahlerfolg der AfD, weil alle über kein anderes Thema als „kriminelle Ausländer“ mehr gesprochen haben. www.deutschlandfunk.de/interview-mi...

A roadmap toward genome-wide CRISPR screening throughout the organism Genome-wide CRISPR screening in the organism has tremendous potential to answer long-standing questions of physiology and disease; however, technical limitations have prevented its broad application. ...

Can we perform genome-wide screens in any cell type in the body?! Excited to share our roadmap for leveraging advances in sgRNA delivery, library design, and phenotypic selection to enable unprecedented genetic dissection of organismal physiology and disease.

www.cell.com/cell-genomic...

On February 12, shortly before “High noon”, scientists at German research campuses, including here in Heidelberg, will stand up for Democracy: “facts, not fake news are needed for democracy”. See aufstehenfuerdemokratie.de/englisch/ – there is also find a Petition related to the cause. Get involved.

This is true. LA County has a population greater than that of 40 individual U.S. states.

Transformer: The Deep Chemistry of Life and Death — Nick Lane What brings the Earth to life, and our own lives to an end? Nick Lane turns the standard view upside down, focusing on Krebs cycle

Just finished the book "Transformer" by Nick Lane, great inspiration to evolutionary biologists, bochemists and, yes, also neuroscientists - its all about transformation of organic molecules and energy flow and not (only) about genes. Highly recommended nick-lane.net/books/transf...

Heat acclimation induces hypothalamic temperature sensitivity that promotes heat tolerance Nature Neuroscience - After long-term heat exposure, a discrete group of hypothalamic neurons in the anterior ventromedial preoptic area become hyperactive and acquire temperature sensitivity. This...

A short, personal account how our recent heat acclimation study came to life -- paywall-free version can be found here rdcu.be/d38Xr

Interesting thoughts on the type of biological problems AI research can help with, the complexity of biology that requires human intellect (and cannot be replaced by AI -- at least not currently, but I think it never will...), and human language that connects it all.

Many academics point to bioRxiv as “the one thing improving science publishing”.

If so, the one thing you all can do is persuade colleagues to submit and make this a norm. 1/2

Pain research: Exciting insight into "silent" (or "sleeping") pain-sensing neurons from the Lampert Lab!

..thanks als for your contribution to the piece by @thetransmitter.bsky.social

www.thetransmitter.org/thermoregula...

Thanks very much Ramón! Did you play any soccer lately? I very much enjoyed our time at the Hyp GRC last summer.

Thanks Andrew - yes, good old (and not always easy) times when we made our first steps as PIs back at the MDC in Berlin.