Together these data demonstrate that MMP9+ neurons receive stronger inhibitory inputs than ErrBeta+ motor neurons and that there is a specific soma-near synaptic loss of inhibitory synapses on MMP9+ motor neurons that starts before the somatic spinal motor neurons are affected in SOD1G93A-induced ALS, while glutamatergic inputs are not altered at early disease stages. The gene discussed is MMP9; the disease is amyotrophic lateral sclerosis.