Jan Siemens

#postdoc #neuroscience #bioengineering #neuromodulation #focusedultrasound #heidelberg

5/5 PIs: Jan Siemens (Pharmacology, Heidelberg) & Peer Fischer (IMSEAM, Heidelberg).
For more information: see flyer above
➡️ Details & application platform: www.health-life-sciences.de/opportunitie...

4/5 Fit: neuroscience + physics/translation interest, or engineering (optics/acoustics) + strong interest in animal-model neuroscience.

3/5 Mouse models include diet-induced obesity and myocardial ischemia/reperfusion injury (metabolic + cardiovascular phenotyping).

2/5 Two approaches we’ll compare:
• IR fiber-optic heating
• low-intensity focused ultrasound (fUS)

1/5 We’re exploring a new strategy: instead of external cooling/warming, modulate the brain’s own thermostat circuits (hypothalamic preoptic area) to shift whole-body physiology from within.

📣 Postdoc position in Heidelberg (Neurobiology × Engineering): neuromodulation of thermoregulatory brain circuits to improve health.
Deadline: March 31, 2026.

6/6
Take-home: a circuit logic linking ambient heat to both cooling physiology and appetite — adding a “temperature layer” to energy-balance models. 🧩
#neuroscience #thermoregulation #hypothalamus #metabolism

5/6
Feeding is also under circuit control: VMPO LepR→PVH suppresses food intake. 🍽️⬇️

4/6
Inhibiting either pathway causes hyperthermia — strongest under heat stress (36°C). 🌡️

3/6
Both pathways shape heat-defense physiology (incl. BAT-related outputs), with distinct roles. ♨️

2/6
These neurons project to multiple brain regions, including two intra-hypothalamic pathways: VMPO LepR→PVH and VMPO LepR→DMH. 🔀

1/6
We identify neuronal pathways that originate from warm-responsive VMPO LepR neurons in the preoptic area — a core thermoregulation hub. 🧠

Thermal-state-dependent control of body temperature and feeding by two intra-hypothalamic pathways Bouaouda et al. identify VMPOLepR projections to the PVH and DMH as intra-hypothalamic circuits linking thermal state to energy balance. These pathways are required for thermoregulation under heat str...

📄 Happy to share our new Current Biology paper: we identify two intra-hypothalamic pathways that couple ambient heat ↔ physiology ↔ feeding. Here’s the gist 👇
www.cell.com/current-biol...

Outside temperature affects our eating habits: when it’s warm, many of us eat less.
How does the brain link thermal state to appetite — and prevent overheating? ☀️🧠

Warum manche Menschen schneller frieren als andere - selbst die Wissenschaft tut sich schwer Temperaturwahrnehmung ist einer der ursprünglichsten Sinne des Menschen. Warum ist das so? Fragen an den Pharmakologen Jan-Erik Siemens.

I just did an interview in the Sueddeutsche Zeitung about how we detect cold temperatures — the journalist, Felix Hütten, did a nice job to make it accessible also for non-scientists.

www.sueddeutsche.de/gesundheit/m...

It was really one of the best conferences I have ever attended: great science in a friendly atmosphere and a gorgeous setting.

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!).