Direction-selective laterodorsal thalamic nucleus encodes optic flow and turning in spatial navigation

Vision is crucial for efficient navigation, but how the brain transforms visual signals into navigational cues remains unclear. The laterodorsal thalamic nucleus (LD), with strong connections to visual and navigation circuits, is well positioned for this function, yet its role has been largely unexplored. In mice, we found that LD neurons exhibit strong direction selectivity, with a dominant directional preference for contralateral-to-ipsilateral visual motion, mirroring horizontal optic flow during contraversive turning. In freely moving animals, LD ensembles were preferentially activated during contraversive rather than ipsiversive turns in a vision-dependent manner, enabling the encoding of turning direction. Optogenetic activation or suppression of LD during learned navigational tasks selectively biased turning decisions in accordance with its directional preference. These findings suggest that by converting visual motion into egocentric turning cues, LD may serve as a critical hub linking vision to navigation and contribute to spatial cognition and memory.