Journal of Neuroscience, Vol 9, 149-159, Copyright © 1989 by Society for Neuroscience
Adaptation to suppression of visual information during catching
F Lacquaniti and C Maioli
Istituto di Fisiologia dei Centri Nervosi, CNR, Milan, Italy.
We address the problem of whether and how adaptation to suppression of
visual information occurs in catching behavior. To this end, subjects were
provided with advance information about the height of fall and the mass of
a ball and an auditory cue signaled the time of release. Adaptation did
occur, as indicated by the unimpaired ability to catch the ball without
vision; however, it involved a major reorganization of the muscle
responses. The subjects were unable to produce anticipatory activity
consistently, but preset the responses elicited by the impact. These
responses were more complex and prolonged than those observed in the
control experiments (with vision). In particular, medium- and long- latency
responses were much larger, and the changes in elbow, wrist, and
metacarpophalangeal angles following impact were more oscillatory than in
the control. The general pattern of the EMG responses switched from that
characteristic of catching with vision to that characteristic of catching
without vision from the first trial of each experiment. However, the
responses produced without vision were calibrated adaptively in the course
of an experiment. In fact, the limb oscillations induced by the impact were
significantly larger in the first trial than in the following trials. This
seems to suggest that the parameters of the responses are adjusted based on
an internal model of the dynamic interaction between the falling ball and
the limb. This model is initially constructed from a priori knowledge on
impact parameters and is subsequently updated on the basis of the
kinesthetic and cutaneous information obtained during the first trial.
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