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

Abstract

Eisen et al, Mirror Neurons in ALS 2 Declaration of interest:The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. Eisen et al, Mirror Neurons in ALS 3 Abbreviations:ALS: Amyotrophic lateral sclerosis; ADM: adductor digiti minimi; APB: abductor pollicic brevis; bvFTD: Behavioral variant of frontotemporal dementia; FTD: Frontotemporal dementia; fMRI: functional MRI; MNS: Mirror neuron system; M1: Primary motor cortex; PTNs: Pyramidal tract neurons; vMPFC: Ventral medial prefrontal cortex. Eisen et al, Mirror Neurons in ALS 4 AbstractThere is growing evidence that mirror neurons, initially discovered over two decades ago in the monkey, are present in the human brain. In the monkey, mirror neurons characteristically fire not only when it is performing an action, such as grasping an object, but also when observing a similar action performed by another agent (human or monkey). In this review we discuss the origin, cortical distribution and possible functions of mirror neurons as a background to exploring their potential relevance in amyotrophic lateral sclerosis (ALS). We have recently proposed that ALS (and the related condition of frontotemporal dementia) may be viewed as a failure of interlinked functional complexes having their origins in key evolutionary adaptations. The mirror neuron system is considered by many to be the basis of primates' social cognition, with a clear evolutionary advantage. Impaired empathy and motor control has been related to a defective mirror neuron system. In ALS, the mirror neuron system might be implicated in empathy, the split-hand syndrome, gait, speech, and related languagegesture impairments.Eisen et al, Mirror Neurons in ALS 5

Cortical influences drive amyotrophic lateral sclerosis

“…Taken together, these changes indicate the development of cortical hyperexcitability. In terms of other contributing influences, involvement of transcallosal pathways has been identified,42 which is thought to underlie the development of mirror movements 34…”

“…Separately, there is a subset of patients with ALS who do not manifest FTD, but in whom social cognition, particularly ‘theory of mind’, may be affected 34. This impairment may be related to dysfunctions of the neocortical mirror neuron system and other cortical regions related to action processing and understanding 35…”

Kinnier Wilson’s puzzling features of amyotrophic lateral sclerosis

“…Multiple motor representations in the primary motor area and in the parietal lobe interconnected by parieto-frontal circuits, widely overlapped, form a complex motor organisation. Brain regional activity elicited by observed movement of specific body parts overlaps with that elicited by actual movement, but there are differences in physical versus observed movement which, at least in part, is dependent on mirror neuron activity 63. Compared with actual movement execution, M1 PTNs show greatly attenuated activity during action observation.…”

Behavioral and TMS Markers of Action Observation Might Reflect Distinct Neuronal Processes

“…The coupling between observed and executed movements is thought to be carried out by a perception-action system (often called mirror-neuron system; Rizzolatti and Craighero, 2004 ; Kilner et al, 2007 ; Fabbri-Destro and Rizzolatti, 2008 ; Keysers and Fadiga, 2008 ; Cattaneo and Rizzolatti, 2009 ; Casile et al, 2011 ; Kilner and Lemon, 2013 ; Cook et al, 2014 ; Rizzolatti and Fogassi, 2014 ; Simpson et al, 2014 ). This perspective has fueled fundamental (see, Keysers and Fadiga, 2008 ; Caspers et al, 2010 ; Naish et al, 2014 , for reviews and overviews) and clinical research (see, Rizzolatti et al, 2009 ; Buccino, 2014 ; Eisen et al, 2015 ; Burzi et al, 2016 , for reviews and overviews) on the neuronal processes involved in action observation and their effects on behavior. In this endeavor, researchers have taken advantage of behavioral paradigms as well as several neuroimaging techniques [i.e., functional magnetic resonance imaging (fMRI), electro/magnetoencephalography and transcranial magnetic stimulation (TMS)].…”