Paw switching with lateralized cholinergic modulation

Motor preferences, such as handedness, reflect fundamental asymmetries in brain function and behavior across vertebrate species, including humans and rodents1. Although individual hand or paw preferences are typically stable, they can be reshaped through experience or training, underscoring the plasticity of lateralized motor circuits2. However, the neural mechanisms that enable this behavioral switching remain unclear. Here we show that experience-driven shifts in paw preference in mice arise from asymmetric cholinergic modulation between the two hemispheres. Using a behavioral paradigm designed to induce paw switching, we found that a subset of animals developed a stable change in preference following training. Selective activation or inhibition of cholinergic neurons on one side of the brain was sufficient to bias this switching behavior. During lateralized movements, an endogenous imbalance in cholinergic activity emerges between the hemispheres, suggesting that interhemispheric cholinergic asymmetry enables motor flexibility. These findings identify a previously unrecognized mechanism by which cholinergic signaling dynamically regulates lateralized motor control, providing insight into how hemispheric imbalances may shape persistent individual motor preferences.