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Amyotrophic Lateral Sclerosis (ALS) is a motor neuron disease characterized by the progressive atrophy of both the first and the second motor neurons. Although the cognitive profile of ALS patients has already been defined by the occurrence of language dysfunctions and frontal deficit symptoms, it is less clear whether the degeneration of upper and lower motor neurons affects motor imagery abilities. Here, we directly investigated motor imagery in ALS patients by means of an established task that allows to examine the presence of the effects of the biomechanical constraints. Twenty-three ALS patients and 23 neurologically unimpaired participants have been administered with the (1) hand laterality task (HLT) in which participants were asked to judge the laterality of a rotated hand and the (2) mirror letter discrimination task (MLD) in which participants were asked to judge whether a rotated alphanumeric character was in its canonical or mirror-reversed form (i.e. control task). Results show that patients present the same pattern of performance as unimpaired participants at the MLD, while at the HLT, they present only partially with the effects of biomechanical constraints. Taken together, our findings provide evidences that motor imagery abilities, related to the mental simulation of an action, are affected by this progressive disease.

4 Neuromuscolar Omnicenter (NEMO), A.O. Niguarda Ca’ Granda, Piazza Ospedale Maggiore no. 3, 20162 Milan, MI, Italy Moreover, the authors also discovered three (3) typos in the reported Results (mixed ANOVA) on the hand laterality task (HLT): The paper reports 113.484 for the Angle of rotation by Stimulus view interaction, where the degrees of freedom should actually be 80.466. Secondly, the F for the factor Angle of rotation should be 33.669 and not 36.670. Finally, the t value of the Effect of stimulus orientation contains an inversion in digits: It should read 4.629 and not 4.692. Table 2 Average percentage of correct answers for control group and ALS patients