Article

Mirror movements are a transient phenomenon during childhood, which decrease
in intensity with motor development. An increasing inhibitory competence
resulting in the ability of movement lateralization is thought to be the
underlying mechanism. We aimed to quantify unintended mirror movements
systematically across the lifespan and to investigate the influences of age, sex,
handedness, and task frequency. Method A total of 236 participants (127 females,
109 males; 216 right-handed, 20 left-handed; age range 3-96y, median 25y 8mo)
first performed four clinical routine tests while mirror movements were rated by
the observer. They were then asked to hold a force transducer in each hand
between the thumb and index finger and to perform oscillatory grip force changes
in one hand, while the other hand had to prevent the force transducer from
dropping. Results Age showed a strong nonlinear effect on the mirror-movement
ratio (the amplitude ratio of the mirror and active hand, adjusted by the
respective maximum grip force). Initially, there was a steep decline in the
mirror-movement ratio during childhood and adolescence, followed by a gradual
rise during adulthood. Males had lower mirror-movement ratios than females. The
high-frequency condition triggered lower mirror-movement ratios. No significant
differences of mirror movements between dominant and non-dominant hand, or left-
and right-handed participants, were found. Interpretation This study provides,
for the first time to our knowledge, normative values of mirror movements across
the lifespan that can aid differentiation between physiological and pathological
mirror movements.
CI - (c) The Authors. Journal compilation (c) Mac Keith Press 2010.

Langue : ANGLAIS