Does dysfunction of the mirror neuron system contribute to symptoms in amyotrophic lateral sclerosis?
There 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. This can include loss of the direct projections from the corticospinal tract, and this is at least part of the explanation for impaired motor control in ALS. Since, in the monkey, corticospinal neurons also show mirror properties, ALS in humans might also affect the mirror neuron system. We speculate that a defective mirror neuron system might contribute to other ALS deficits affecting motor imagery, gesture, language and empathy.
Division of Neurology, University of British Columbia, 2826 Highbury Street, Vancouver, BC V6R 3T6, Canada. Electronic address: Eisen@mail.ubc.ca.
Andrew
A
Eisen
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, Queen Square, London, United Kingdom.
Roger
R
Lemon
Bushell Chair of Neurology, University of Sydney, Australia.
Matthew C
MC
Kiernan
Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
Michael
M
Hornberger
Oxford University Nuffield Department of Clinical Neurosciences, Oxford, United Kingdom.
Martin R
MR
Turner
D000690:Amyotrophic Lateral Sclerosis / Q000503:physiopathology*; D003071:Cognition / Q000502:physiology; D004645:Empathy / Q000502:physiology; D005684:Gait / Q000502:physiology; D006801:Humans; D059167:Mirror Neurons / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology; D011712:Pyramidal Tracts / Q000503:physiopathology*; D013060:Speech / Q000502:physiology
Amyotrophic lateral sclerosis; Cognition; Empathy; Mirror neurons; Motor cortex