This reveals a simple learning rule:
Coincident visual input + octopamine release is sufficient to induce plasticity at an inhibitory synapse.

A two-factor rule for unsupervised spatial learning.

Is it sufficient?

Strikingly, pairing activation of octopamine neurons with a visual cue was enough to drive rapid plasticity — even when head-direction neurons were silenced during learning.

EL neurons receive input from head-direction cells and synapse directly onto nearby visual presynaptic terminals — right next to the inhibitory synapses that change with experience.
This forms a local feedback loop.

We discovered that a third neuron type provides the missing signal.

Neurons called EL neurons release the neuromodulator octopamine in a highly localized pattern that tracks the fly’s head direction.

*First preprint from our lab* !!!!!
How does the brain learn to anchor its internal sense of direction to the outside world? 🧭
led by Mark Plitt @markplitt.bsky.social & Dan Turner-Evans, w/ Vivek Jayaraman:
“Octopamine instructs head direction plasticity” www.biorxiv.org/content/10.6...
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