EPISODE 46: Turning in Time: Neural Sequences in the Worm Brain

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.

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🧬 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.

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🔬 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.

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⚡ 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.

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🧠 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.

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🧠 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.

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📄 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

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