Using chronic 32-channel laminar arrays, the team recorded extracellular activity (5,889 single units, 384 channels) in 8 mice locomoting on a motorized treadmill over 8 weeks. Unsupervised clustering identified speed-positively related (70.8%) and speed-inversely related (29.2%) units that share a common speed threshold of about 2.3 m/min. The minority speed-inversely related population decoded speed with significantly higher accuracy via inverse-sigmoid transformation than the larger speed-positively related population or all units combined, an advantage that generalized across animals in leave-one-animal-out cross-validation. LFP band power also showed sigmoidal tuning to locomotion speed but decoded speed with lower fidelity.
Sigmoidal Decoding of Locomotion Speed in Mouse M1
Summary
The study shows mouse primary motor cortex encodes locomotion speed through a sigmoidal state-transition mechanism carried by two functionally distinct spiking populations, a framework that also extends to local field potential (LFP) band power. Using chronic 32-channel laminar arrays in 8 mice, the team recorded 5,889 single units across 384 channels and clustered them into speed-positively related (70.8%) and speed-inversely related (29.2%) groups sharing a speed threshold of about 2.3 m/min. The minority speed-inversely related population decoded speed more accurately via inverse-sigmoid transformation, generalizing across animals. The authors say the findings point toward stable, calibration-light brain-machine interface design.
Why it matters
Beyond the neural-coding insight, the counterintuitive result that the smaller speed-inversely related population decodes better than the majority is a practical lead for calibration-light motor decoders.
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pubmed.ncbi.nlm.nih.gov 2026-07-22