Cortical responses to the mirror box illusion: a high-resolution EEG study

Exp Brain Res. 2011 Dec;215(3-4):345-57. doi: 10.1007/s00221-011-2902-x. Epub 2011 Oct 25.

Abstract

The mirror box illusion has proven a helpful therapy in pathologies such as phantom limb pain, and although the effect has been suggested to be a result of the interaction between pain, vision, touch, and proprioception, the mechanisms are still unknown. Multichannel (124) brain responses were investigated in healthy men (N = 11) and women (N = 14) during the mirror box illusion. Tactile somatosensory evoked potentials were recorded from the right thumb during two control conditions and two illusions: (control 1) no mirror: looking at the physical right thumb during stimulation, (control 2) no mirror: looking at the physical left thumb during stimulation, (illusion 1) mirror: the illusion that both thumbs were stimulated, and (illusion 2) mirror: the illusion that none of the thumbs were stimulated. In men, a significant medial shift in the y coordinate of the N70 dipole in illusion 2 (P = 0.021) was found when compared with illusion 1. No dipole shift was found for women. Additionally, men showed higher prevalence of P180 cingulate cortex activation during illusion 2 when compared with control 1 and 2 (P = 0.002). During illusion 2, the degree of conformity with the statement "The hand in the mirror feels like my other hand" was negatively correlated with the N70 x coordinate for men and positively correlated with the N70 z coordinate for women. In conclusion, short-term cortical plasticity can be induced by a mismatch between visual input and location of tactile stimulation in men. The present study suggests that gender differences exist in the perception of the mirror box illusion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Cerebral Cortex / physiology*
  • Electroencephalography / methods
  • Evoked Potentials, Somatosensory / physiology*
  • Female
  • Functional Laterality / physiology*
  • Humans
  • Illusions / physiology*
  • Male
  • Photic Stimulation / methods
  • Physical Stimulation / instrumentation
  • Physical Stimulation / methods
  • Sex Characteristics*
  • Touch Perception / physiology*