Updating an allocentric goal from lateralised egocentric visual memories.

Animals navigate by combining egocentric (viewpoint-dependent) and allocentric (world-referenced) spatial representations, yet how their brains achieve this integration remains unclear. Here we show how the brains of insect expert navigators, such as ants, accomplish this task. Field experiments reveal that ants recognise long-term egocentric visual memories - assumed to be encoded in the Mushroom Bodies - via a lateralized mechanism: instead of memorising views while facing their goal, ants store these memories by looking to the sides. Recognition signals inform whether to turn left or right, but do not directly drive motor responses. Instead, they are processed separately - presumably in the two brain hemispheres - and integrated to update a goal heading in an ancestral, central brain region -the central complex. This goal heading -now anchored in an allocentric frame-is then used with celestial compass cues for robust steering. Computational models based on insect neural circuits validate this two-stage process, demonstrating how noisy, viewpoint-dependent lateralized inputs are transformed into stable allocentric directional control. These findings reveal how compact brains leverage bilateral processing to combine spatial representations for visual navigation.