Data from: Neural tuning functions underlie both generalization and interference

In sports, the role of backswing is considered critical for generating a
good shot, even though it plays no direct role in hitting the ball. We
recently demonstrated the scientific basis of this phenomenon by showing
that immediate past movement affects the learning and recall of motor
memories. This effect occurred regardless of whether the past contextual
movement was performed actively, passively, or shown visually. In force
field studies, it has been shown that motor memories generalize locally
and that the level of compensation decays as a function of movement angle
away from the trained movement. Here we examine if the contextual effect
of past movement exhibits similar patterns of generalization and whether
it can explain behavior seen in interference studies. Using a single
force-field learning task, the directional tuning curves of both the prior
contextual movement and the subsequent force field adaptive movements were
measured. The adaptation movement direction showed strong directional
tuning, decaying to zero by 90° relative to the training direction. The
contextual movement direction exhibited a similar directional tuning,
although the effect was always above 60%. We then investigated the
directional tuning of the passive contextual movement using interference
tasks, where the contextual movements that uniquely specified the force
field direction were separated by ±15° or ±45°. Both groups showed a
pronounced tuning effect, which could be well explained by the directional
tuning functions for single force fields. Our results show that contextual
effect of past movement influences predictive force compensation, even
when adaptation does not require contextual information. However, when
such past movement contextual information is crucial to the task, such as
in an interference study, it plays a strong role in motor memory learning
and recall. This work demonstrates that similar tuning responses underlie
both generalization of movement direction during dynamic learning and
contextual movements in both single force field and interference tasks.