INTERMANUAL TRANSFER OF PROXIMAL AND DISTAL MOTOR ENGRAMS IN HUMANS

We studied intermanual motor transfer for right-to-left or left-to-rig ht direction of transfer between either proximal or distal upper extre mity muscle groups. The influence of previously acquired motor engrams (original learning, OL) on learning efficiency of the contralateral s ide (transfer learning, TL) was examined in 26 right-handed healthy su bjects. The task consisted of the drawing of meaningless figures. Duri ng TL, OL figures had to be reproduced as vertical mirror reversals. D ata revealed a benefit for right-to-left but not left-to-right directi on of transfer for time to complete a figure as well as a left-to-righ t transfer benefit for spatial motor precision. Furthermore, a benefit for intermanual transfer of training between proximal but not distal muscle groups was found when movement time to complete a figure was ev aluated. Of special interest was the observation of a disadvantage due to prior contralateral learning for performance at right distal effec ters. The asymmetrical transfer benefits with respect to side are in l ine with previous findings and support the proficiency model and the c ross-activation model. Results further showed that intermanual transfe r of training might differ with respect to muscle group involvement an d suggest that, although primarily facilitating, previous opposite han d training may lead to inhibitory in influences on subsequent contrala teral reproduction.