The corpus callosum is a signpost to the interhemispheric highways underpinning the widespread cerebral pathology that typifies the syndrome of ALS

The brain has become axiomatic to understanding pathogenesis in amyotrophic lateral sclerosis (ALS), not least given the clinical, molecular and genetic overlap with frontotemporal dementia.1 ALS, although defined in part by its lower motor neuron degeneration, now appears misfiled alongside the neuromuscular disorders. The corpus callosum (CC, latin translation: tough body) is a pervasive cerebral integrator, and a consistent part of the in vivo cerebral white matter MRI signature of ALS,2 noted in post mortem studies many decades prior to diffusion tensor imaging (DTI).3 ,4 The JNNP paper by Zhang et al5 uses advanced MRI analysis to explore symmetrical interhemispheric functional connectivity in ALS in relation to the regional anatomy of the CC.

Loss of interhemispheric connectivity in ALS was initially …