The Ring Attractor and Quantum Compass
How does an insect brain represent a compass heading? The ring attractor is a neural circuit where activity forms a bump that rotates around a ring of neurons, tracking the animal’s heading. In Drosophila, this circuit lives in the ellipsoid body (E-PG neurons). In our model, it serves as the bridge between quantum chemistry and behaviour. The Radical-Pair Compass The compass sensor models cryptochrome — a flavoprotein in the insect eye that forms radical pairs under blue light. The singlet yield of the radical pair depends on the orientation of the Earth’s magnetic field relative to the molecule’s hyperfine axis. This anisotropy is tiny (a few percent) but sufficient for navigation. ...