Sensorimotor functional connectivity changes in amyotrophic lateral sclerosis

We investigated whether the functional connections to the primary sensorimotor cortex (SMC) at rest are abnormal in 26 patients with amyotrophic lateral sclerosis (ALS) and whether such changes are related to the corticospinal tract (CST) damage, measured using diffusion tensor magnetic resonance imaging (DT MRI). ALS patients versus controls showed a significantly increased functional connectivity between the left SMC and the right cingulate cortex, parahippocampal gyrus, and cerebellum-crus II. No right SMC connectivity changes were found. The pattern of increased functional connectivity to the left SMC was more widespread when considering only patients with no CST DT MRI abnormalities than the whole group of patients. In this patient group, functional connectivity was also increased between the right SMC and the right parahippocampal gyrus. On the contrary, in ALS patients with CST damage (as assessed using DT MRI) versus controls, functional connectivity was increased between the left SMC and the right cingulate cortex only, while it was decreased between the right SMC and the right cerebellum-lobule VI. In ALS patients, disease severity correlated with reduced SMC functional connectivity. Functional brain changes do occur in ALS with mild disability. These changes might have a role in compensating for (limited) structural damage and might exhaust with increasing burden of disease pathology.