Importance The identification of the chromosome 9 open reading frame 72 (c9orf72) gene
hexanucleotide repeat expansion represents a major advance in the understanding of
amyotrophic lateral sclerosis (ALS) pathogenesis. The pathophysiological mechanism by
which thec9orf72gene expansion leads to neurodegeneration is not yet elucidated. Cortical
hyperexcitability is potentially an important pathophysiological process in sporadic ALS and
familial ALS (FALS). Objective To investigate whether cortical hyperexcitability forms the …