Welcome to the next episode of the WOrM Podcast 🪱

Today we’re looking at something deceptively simple: a turn.

But not just that a worm turns —

how the brain decides to do it.

⸻

🧬 The central idea

Turning in C. elegans is not a reflex.

It’s a sequence.

A structured, repeatable pattern of neural activity that links:

• sensation

• decision

• and movement

into a single behavioural output.

⸻

🔬 What’s really happening?

Using whole-brain calcium imaging, this study captures activity across the nervous system during olfactory navigation.

What emerges is clear:

• turns act as error-correction events

• they occur when the worm deviates from its path

• and they are executed through ordered neural sequences

Each turn is not random.

It is built.

⸻

⚡ A sequence, not a signal

During a turn:

• specific neurons activate

• in a stereotyped order

• across time

Some neurons respond to sensory cues.

Others anticipate the direction of the upcoming turn.

This is not reaction.

It is prediction unfolding in time.

⸻

🧠 The role of modulation

A key player here is tyramine.

It helps coordinate these neural sequences —

linking circuit structure to dynamic control of behaviour.

So the system is not just wired.

It is tuned.

⸻

🧠 The take-home message

Behaviour is not the output of single neurons.

It is the product of time-ordered neural activity.

In this case:

sensory input → neural sequence → predicted action

And the shift is important:

To understand behaviour, we need to think in time, not just space.

⸻

📄 Paper discussed

Kramer, T. S.; Wan, F. K.; Pugliese, S. M.; Atanas, A. A.; Pradhan, S.; Hiser, A. W.; Godinez, L. M.; Luo, J.; Bueno, E.; Felt, T.; Flavell, S. W. (2026)

Neural sequences underlying directed turning in Caenorhabditis elegans

Nature

https://doi.org/10.1038/s41593-026-02257-5

If you enjoyed this episode, please like, follow, and subscribe wherever you listen to the WOrM Podcast ⭐🎧 It really helps others in the community find the show.

This podcast is generated with artificial intelligence and curated by Veeren. If you’d like your publication featured on the show, please get in touch.

📩 More info:

🔗 www.veerenchauhan.com

📧 veeren.chauhan@nottingham.ac.uk

Welcome to the next episode of the WOrM Podcast 🪱

Today we’re talking about something fundamental — feeding behaviour — but through a lens you might not expect.

Not calories.

Not food availability.

But fat composition.

⸻

🧬 The central idea

In C. elegans, feeding isn’t just about energy — it’s about lipid balance.

Specifically, the ratio of:

• saturated fatty acids (SFAs)

• and monounsaturated fatty acids (MUFAs)

And this balance determines whether worms:

• stay on food

• leave food

• or actively ignore it

⸻

🔬 What’s really being sensed?

This isn’t happening at the surface.

It’s happening at the endoplasmic reticulum (ER) — where lipid composition alters membrane properties and activates the stress sensor IRE-1.

That signal is then translated into behaviour through:

• neuronal serotonin

• AMPK signalling

• and a neuropeptide system

⸻

⚡ A new behavioural state: “food apathy”

One of the most interesting outcomes in this study is a state the authors call food apathy.

Worms:

• leave concentrated food

• roam even when food is present

• and reduce overall intake

This is not starvation.

It’s not avoidance of toxins.

It’s a metabolically driven behavioural shift.

⸻

🧠 The big connection: GLP-1-like signalling

Here’s where it gets very interesting.

The pathway that drives this behaviour — PDF-1 / PDFR-1 — shows structural and functional similarity to:

• GLP-1

• GIP

• glucagon-related signalling

In other words, the same systems now targeted by weight-loss drugs may have deep evolutionary roots in simple organisms like worms.

Even more striking — a peptide derived from this worm pathway shows:

• reduced food intake

• improved insulin sensitivity

in mice.

⸻

🧠 The take-home message

Feeding behaviour is not just about hunger.

It’s about how metabolism is sensed and interpreted.

In this case:

lipids → ER stress → neuronal signalling → behaviour

And the implication is big:

Some of the most important metabolic signalling systems in humans may have started as basic lipid-sensing circuits in simple organisms.

⸻

📄 Paper discussed

Zhu, F.; Castillo-Quan, J. I.; Ogawa, T.; Wu, Z.; Ding, L.; Sura, M.; Watanabe, Y.; Lentsch, H.; Fernández-Cárdenas, L. P.; Dag, U.; Beck-Sickinger, A.; Wang, M. C.; Kahn, C. R.; Blackwell, T. K. (2026)

Fatty acid regulation of feeding in Caenorhabditis elegans reveals the potential ancestral origin of a GLP-1-like multiagonist signaling system

Proceedings of the National Academy of Sciences (PNAS)

DOI: 10.1073/pnas.2530979123

If you enjoyed this episode, please like, follow, and subscribe wherever you listen to the WOrM Podcast ⭐🎧 It really helps others in the community find the show.

This podcast is generated with artificial intelligence and curated by Veeren. If you’d like your publication featured on the show, please get in touch.

📩 More info:

🔗 www.veerenchauhan.com

📧 veeren.chauhan@nottingham.ac.uk