Longitudinal monitoring of motor neuron circuitry in FALS rats using in-vivo phMRI.

Amyotrophic lateral sclerosis (ALS) presents challenges for diagnosis and objective monitoring of disease progression. We show, using pharmacologic MRI, that alterations in motor circuitry can be characterized using a passive stimulus in a rat model of familial ALS as a function of symptom progression. Presymptomatic familial ALS rats had a pattern of activation to amphetamine that was statistically indistinguishable from the wild-type controls. In contrast, symptomatic rats showed significantly decreased response in sensorimotor cortex and increased response in M2 motor cortex, caudate/putamen, and thalamus. These results are similar to findings in humans of altered response to motor tasks in ALS. It may be plausible to use a passive amphetamine challenge as a biomarker to assess progression of the disease and efficacy of potential treatments.