Interhemispheric and ipsilateral connections in Parkinson's disease: relation to mirror movements

Mov Disord. 2007 Apr 30;22(6):813-21. doi: 10.1002/mds.21386.


Mirror movements (MM) occur in early, asymmetric Parkinson's disease (PD). To examine the pathophysiology of MM in PD, we studied 13 PD patients with MM (PD-MM), 7 PD patients without MM (PD-NM), and 14 normal subjects. Cross-correlogram did not detect common synaptic input to motoneuron pools innervating homologous hand muscles in PD-MM patients. Transcranial magnetic stimulation studies showed no significant difference in ipsilateral motor-evoked potentials between PD-MM patients and normal subjects. The MM side of PD-MM patients showed a slower increase in ipsilateral silent period area with higher level of muscle contraction than the non-MM side and normal subjects. There was less interhemispheric inhibition (IHI) at long interstimulus intervals of 20 to 50 ms in PD-MM than PD-NM. IHI reduced short interval intracortical inhibition in normal subjects and PD-NM, but not in PD-MM. IHI significantly increased intracortical facilitation in PD-MM and PD-NM patients, but not in normal subjects. Our results suggest that MM in PD is due to activation of the contralateral motor cortex. PD-MM patients had reduced transcallosal inhibitory effects on cortical output neurons and on intracortical inhibitory circuits compared to PD-NM patients and controls. These deficits in transcallosal inhibition may contribute to MM in PD patients.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brain / physiopathology*
  • Corpus Callosum / anatomy & histology
  • Corpus Callosum / physiopathology
  • Electromyography
  • Female
  • Functional Laterality
  • Humans
  • Male
  • Middle Aged
  • Motor Activity / physiology*
  • Movement Disorders / physiopathology*
  • Parkinson Disease / physiopathology*
  • Reference Values