circuits/Head direction ring attractor

A ring of neurons holding one bump of activity that tracks which way the animal faces. It survives darkness by dead reckoning.

**Computes** Maintains an internal heading estimate and integrates angular velocity when landmarks are absent. **Behaviour** Straight-line holding, menotaxis, return-to-goal navigation. **Timescale** Fast **Pathway** Ring neurons (ER) -> EPG -> PEN / PEG -> PFL3 / DNa02

Stages: - Ring neurons (ER) (input, central-complex) — Visual landmarks, inhibitory onto the compass - EPG (relay, central-complex) — The compass itself — a single activity bump on a ring - PEN / PEG (relay, central-complex) — Rotate the bump using angular velocity - PFL3 / DNa02 (output, lateral-accessory-lobe) — Convert heading error into a turn

The pathway is published anatomy and ships here. The connectivity behind it comes from the source dataset: import a brain to extract the actual neurons and weights.

- The best-characterised recurrent circuit in any brain — the hemibrain is the reference for it. - Ring neurons are inhibitory: landmarks pin the bump by suppressing everywhere else.

Cite as: Seelig & Jayaraman 2015; Turner-Evans et al. 2017; Hulse et al. 2021.