Morphological and functional changes in innervation of a fast forelimb muscle in SOD1-G85R mice

► Innervation of mouse forelimb muscles was assayed by imaging neuronally-expressed YFP. ► Symptomatic SOD1-G85R mice lost motor terminals and large-diameter motor axons. ► Activation by action potentials was detected as YFP florescence changes in terminals. ► > 90% of surviving SOD1-G85R motor terminals remained responsive to stimulation.