Exploring motor and visual imagery in Amyotrophic Lateral Sclerosis

Abstract

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.

Primary Motor Cortex Excitability Is Modulated During the Mental Simulation of Hand Movement

“…Response time was calculated Primary motor cortex excitability during motor imagery as the difference (in ms) between stimulus onset and fixation onset to the response box. Visual response methods have been successfully adopted for recording accuracy on the HLT in patient groups [e.g., spinal-cord injury (Fiori et al, 2014) and Amyotrophic lateral sclerosis (Fiori et al, 2013)]. Unlike the present study, however, reaction times were not simultaneously recorded in these earlier studies.…”

Does dysfunction of the mirror neuron system contribute to symptoms in amyotrophic lateral sclerosis?

“…They may share a common neurophysiological basis in the MNS (Gatti et al , 2013). Motor imagery, the ability to imagine movements, is defective in ALS (Stanton 2007) (Fiori et al , 2013). In ALS, motor imagery has been shown to share similar neural networks (the primary motor, premotor, and supplementary motor cortex) as motor execution, as this is not different from normal subjects (Lule et al , 2007).…”

Intention and Motor Representation in Purposive Action

“…Initially this might seem plausible because one task involves hands whereas the other involves letters. However, there are subjects who can perform both tasks but whose performance is not different for hands and letters (Fiori et al. 2012).…”