Supramammillary regulation of locomotion and hippocampal activity

Locomotor speed is a basic input used to calculate one's position, but where this signal comes from is unclear. We identified neurons in the supramammillary nucleus (SuM) of the rodent hypothalamus that were highly correlated with future locomotor speed and reliably drove locomotion when activated. Robust locomotion control was specifically identified in Tac1 (substance P)-expressing (SuM(Tac1+)) neurons, the activation of which selectively controlled the activity of speed-modulated hippocampal neurons. By contrast, Tac1-deficient (SuM(Tac1-)) cells weakly regulated locomotion but potently controlled the spike timing of hippocampal neurons and were sufficient to entrain local network oscillations. These findings emphasize that the SuM not only regulates basic locomotor activity but also selectively shapes hippocampal neural activity in a manner that may support spatial navigation.

Automated summary

Research has identified neurons in the supramammillary nucleus (SuM) that are highly correlated with future locomotor speed and reliably drive locomotion. Specifically, Tac1-expressing neurons in the SuM were found to control the activity of speed-modulated hippocampal neurons. These findings suggest that the SuM not only regulates basic locomotor activity but also selectively shapes hippocampal neural activity in a way that may support spatial navigation.