A. Classification of TMNs into PFF, PFR and PS MU types using k-means clustering based on rheobase and input resistance (R
). B. Rheobase values were significantly lower among mutant PFR and PFF units compared with wild-type (Student's t test, *p = 0.0002 for PFR, **p = 0.0001 for PFF), whereas Rinp values were significantly greater (Student's t test, *p = 0.0009 for PFR, **p = 0.0028 for PFF). Error bars indicate SD. C. F-I relationships of PS, PFR and PFF TMNs in wild-type and mutant mice; color coding is similar to A. D. Simulation of isometric force versus MN input current across the jaw closer motor pool. Dashed lines demarcate normal (gray) and altered (red) muscle dynamic range.