State- and identity-dependent motor neuron excitability shapes cutaneous long-latency reflexes

We show that cutaneous long-latency reflex excitability at the single motor unit level scales with force via two mechanisms: high-threshold units show comparable reflex gain despite biophysical disadvantage, while active units increase excitation probability as drive rises. We further show postexcitatory depression is a hybrid phenomenon combining synchronization-induced spike resetting and, presumably, centrally mediated inhibition. Estimating single-unit reflex characteristics with 1,000 stimuli also proved significantly more reliable than in previous work using at most 300 repetitions.