OLIG2 and amyotrophic lateral sclerosis: Reduced expression of Olig2 in neuronal cells switches cell fate from differentiation to death, contributing to acute/chronic diseases, including psychiatric disorders, Alzheimer’s disease and Amyotrophic Lateral Sclerosis (ALS), and thus proposing this factor as a potential therapeutic target for treatment of these conditions [79,80,81,82,83,84].