Predatory orienting is jointly controlled by optic tectum and pretectum

The optic tectum and pretectum have been implicated in hunting behaviour in several species but how activity in these regions is coordinated to control target-directed orienting manoeuvres is not understood. We performed two-photon calcium imaging across these brain regions in larval zebrafish, which revealed space and rate-coded premotor activity associated with graded, prey-directed eye and tail movements. Consistent with imaging data, intensity-modulated optogenetic stimulation of pretectum induced progressively more lateralised contraversive orienting behaviour and spatially patterned stimulation of optic tectum revealed a motor map along the anterior-posterior axis that primarily generated ipsiversive responses. Anatomical tracing and laser axotomies indicated that pretectal neurons control contraversive turns via a crossed pretectobulbar pathway whereas optic tectum shows topographically patterned output with a major uncrossed projection to hindbrain. Our data support a model in which premotor activity across pretectum and optic tectum collectively controls predatory orienting via both crossed and uncrossed (pre)-tectobulbar pathways.