CONTRIBUTION OF THE PROPRIOMUSCULAR CHANNEL TO MOVEMENT CODING IN CHILDREN - A STUDY INVOLVING THE USE OF VIBRATION-INDUCED KINESTHETIC ILLUSION

The specific contribution of the propriomuscular afferent channel to t he coding of movement was investigated in children aged 5, 7 and 9 yea rs by applying vibration to muscle tendons, which is known to elicit k inaesthetic illusions in adults in a motionless limb. Vibrations at va rious frequencies ranging from 20 to 130 Hz were applied to the distal tendon of the right triceps brachii. The subject had to simultaneousl y copy with the left forearm the kinaesthetic sensation thus induced. The ability of the children to discriminate between various real movem ent speeds (2, 5 and 10-degrees/s) was established using the same meth od. In all the children, the vibratory stimulation evoked an illusory sensation of elbow flexion, the velocity of which depended on the subj ect's age and the vibration frequency. At 5 years of age, the perceive d velocity was highest and did not depend on the vibration frequency; it was lower at 7 and 9. It began to depend on the vibration frequency at the age of 9, when higher values were obtained with the median tha n with the extreme frequencies, as in adults. The results indicate tha t propriomuscular information contributes to conscious movement percep tion at each of the ages considered here, but that the processing of t his information varies with age as children become aware of the quanti tative (movement speed) content of the proprioceptive messages.