Multimodal imaging by proton (1H-MRS) and carbon 13 (13C) spectroscopy and developing specific GLT-1 PET ligands are needed to explore glutamate-glutamine cycle dynamics and GLT-1 activity before and after CEF treatment in healthy individuals and in patients with ALS and other neuropsychiatric disorders. Here, SLC1A2 is linked to amyotrophic lateral sclerosis.