Mirrored, imagined and executed movements differentially activated sensorimotor cortex in amputees with and without phantom limb pain Martin Diers, et al. 2010

Phantom Limb Pain Phantom Sensations Phantom Pain Can occur anywhere but most common in amputated limbs 50-85% of people with amputated limbs experience phantom limb pain

Theories CNS PNS Cortical Reorganization and Neuroplasticity Body Schema Neuromatrix Theory …others… PNS Ex. neuromas

Cortical Reorganization and Neuroplasticity Penfield sensory (left) and motor (right) homunculi (Penfield and Boldrey, 1937).

Cortical Reorganization cont. Used microelectrodes to prove cortical plasticity. When 1 finger was amputated, the sensory input from adjacent digits took over The amount of cortical reorganization has been found to be dependent upon the size of the deafferented region(s) Mr. and Mrs. Owl Monkey

More Cortical Reorganization When the ipsilateral face was touched, patient felt touch on face and hand.

“If I’m in a buttload of pain, I need a buttload of pills.” Dr. Gregory House Head of Diagnostic Medicine Princeton-Plainsboro Teaching Hospital

Treatment Options for PLP Pharmaceuticals Opioids Anticonvulsants Lidocaine/mexiletine Clonidine Ketamine Amitriptyline Nonsteroidals anti-inflammatory drugs Calcitonin

More Treatments TENS Deep brain and spinal cord stimulation Acupuncture Virtual reality Mirror visual feedback

Video Clip House: Mirror therapy http://www.youtube.com/watch?v=Tl70d9MR_so

What are Mirror Neurons? Empathy neurons Monkey see- monkey do. Frontal and parietal lobes Vision dominates touch and proprioception (Rock and Victor, 1964) vision dominates = ‘visual capture’

Video Clip American’s Got Talent Magic Tricks http://www.youtube.com/watch?v=6Mpi-MFsq1s

Hypothesis Mirrored movements of the intact hand might provide input into the cortical representation zone that previously received input from the now amputated limb (i.e. cortical reorganization), and, executed and imagined movements might have similar but less pronounced effects.

Design Executed (with dominant or intact hand) Mirrored Imagined (non-dominant or amputated hand)

fMRI 1990’s Measures hemodynamic response (changes in blood flow) Blood flow and blood oxygenation in brain is related to neural activity. Metabolism- neurons don’t store blood & oxygen Disadvantages- Correlation does not imply causation

Mirrored Activation of the sensorimotor cortex contralateral to the hand seen in the mirror in the nonPLP and the HC but not in the PLP.

Executed Activation of the contralateral sensorimotor area in all three groups but ipsilateral cortex was only activated in the nonPLP and HC group.

Imagined Imagined movement activated the supplementary motor are in all groups and the contralateral primary sensorimotor cortex in the nonPLP and HG but not in the PLP

Results Imagined movement in all three groups showed activation in the supplementary motor cortex.

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Conclusions Viewing one’s own hand in a mirror produces activity in sensory and motor cortices contralateral to the hand that is perceived. The larger the shift of neighboring activations into the cortical amputation area, the more pain was present.