Lesions to the lateral mammillary nuclei disrupt spatial learning in rats.

The head direction (HD) signal is thought to originate in the reciprocal connections between the dorsal tegmental nuclei (DTN) and the lateral mammillary nuclei (LMN) and lesions to these structures disrupt the HD signal in downstream structures. Lesions to the DTN also disrupt performance on spatial tasks where directional heading is thought to be important. In Experiment 1, rats with bilateral electrolytic lesions of the LMN and sham controls were trained on 2 tasks previously shown to be sensitive to DTN damage.