NRG1 and amyotrophic lateral sclerosis: In the mature nervous system, NRG1 has a different role in the setting of injury as a potent activator of microglia that can lead to synaptic changes contributing to chronic pain (Calvo et al., 2010, 2011) and neurodegeneration in amyotrophic lateral sclerosis (ALS; Song et al., 2012, 2014; Liu et al., 2018; Schram et al., 2020).