SST and amyotrophic lateral sclerosis: Genes which constitute the three main subgroups of cortical inhibitory GABAergic interneurons (PVALB, SST, VIP) were identified in cluster one [40] This is interesting given that alterations in their excitability patterns cause global hyperexcitability of corticospinal neurons [41], which has long been hypothesised as a trigger for the spread of ALS pathology [42, 43].