Abstract
The mesencephalic locomotor region (MLR) encodes a diverse range of movements, from locomotion to posture and turning behavior. While the cuneiform nucleus (CnF) and pedunculopontine nucleus (PPN), the main components of the MLR, have been recently characterized, little is known about the precuneiform nucleus (PrCnF). To address this gap, we performed somatodendritic morphological analyses and ex vivo functional studies on PrCnF neurons of VGluT2-tdTomato mice and compared them with those of neighboring MLR nuclei. PrCnF neurons exhibited dendritic morphology similar to PPN neurons but distinct from CnF neurons. Functionally, PrCnF neurons displayed higher firing rates and oscillatory activity compared to CnF and PPN neurons, which were correlated with TTX-sensitive high-threshold membrane potential oscillations mediated by the persistent Na⁺ current present in most PrCnF neurons. Unlike PPN and CnF neurons, the majority of PrCnF neurons did not show depolarization-related changes in spike frequency adaptation, indicating that their intrinsic properties support continuous high-frequency spiking. These findings suggest that PrCnF neurons may have a uniform relationship to movement speed similar to CnF neurons and that activation of the PrCnF might be related to higher-speed movements due to their weak spike frequency adaptation and higher firing rates.