CHARACTERISTICS OF TARGET-REACHING IN CATS III - LIFTING AND PROTRACTION WITH AN OBSTACLE IN THE MOVEMENT PATH AND AFTER ITS REMOVAL

Three cats were trained to perform target-reaching to a horizontal tub e with food placed at shoulder level, and the kinematic characteristic s of the movements were investigated by recording the trajectory of th e wrist. From the very onset of training, a vertical obstacle was plac ed in front of the cats. The obstacle forced the animals to perform mo vements with an initial phase dominated by limb-lifting to position th e wrist above the obstacle, followed by a second phase of protraction towards the tube; in the sagittal plane. the movement paths were segme nted with an upwards convexity. After a training period of 1 year (abo ut 7000 movements), the obstacle was removed. All cats then quickly (w ithin a few trials) changed the trajectory so that the main part of pr otraction now occurred in parallel with limb-lifting during the first half of the movement, The initial slope of the sagittal movement path became less steep and the upwards convexity less pronounced. Such traj ectories, which predominated for several experiments after removal of the obstacle, were only slightly different from those observed in cont rol cats not trained with an obstacle. The results are discussed in re lation to a previously proposed hypothesis of motor ''imprinting'' dur ing extensive training in a particular experimental paradigm.