Feedforward postural adjustments in a simple two-joint synergy in patients with Parkinson's disease

Mark L. Latash, Alexander S. Aruin, Ida Neyman, John J. Nicholas, Mark B. Shapiro

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


Patients with Parkinson's disease, age-matched controls and young control subjects performed discrete elbow or wrist movements in a sagittal plane under the instruction to move one of the joints "as fast as possible." Relative stability of the other, postural joint was comparable in all 3 groups, while movement time was the highest in the patients and the lowest in young controls. Typically, EMG patterns in both muscle pairs acting at the joints demonstrated a commonly observed "tri-phasic" pattern. A cross-correlation analysis of the EMGs confirmed virtually simultaneous bursts in the wrist and elbow flexors and in the wrist and elbow extensors. In all 3 groups, there were no signs of anticipatory activation of postural muscles in about 90% of movements. We consider postural anticipation not a separate process, but a separate peripheral pattern of a single control process that may involve a number of joints and muscles. We conclude that the postural deficits in Parkinson's disease are not related to a basic deficit in the ability to generate feedforward postural adjustments but to other factors that may include the specificity of maintaining the vertical posture in the field of gravity.

Original languageEnglish (US)
Pages (from-to)77-89
Number of pages13
JournalElectroencephalography and Clinical Neurophysiology/ Electromyography
Issue number2
StatePublished - Apr 1995

All Science Journal Classification (ASJC) codes

  • General Neuroscience
  • Clinical Neurology


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