The role of movement synchronization with an auditory signal in producing prism adaptation

The prism adaptation procedure is often used to study the plasticity of eye-hand coordination to misalignment of the visual and proprioceptive spatial maps. Misalignment can be resolved by adaptive change in spatial maps of either the eyes or hand or both. In this procedure, pacing pointing movements with a rhythmic auditory signal is usually employed to control movement speed, but the role of the auditory signal itself in producing adaptation has not been examined. The present experiment addressed this issue by testing three conditions: (i) exposure pointing was self-paced without an auditory signal; (ii) exposure pointing was paced by an auditory signal without synchronization; and (iii) exposure pointing was synchronized with the auditory signal. The first condition produced primarily proprioceptive adaptation. The second condition also produced primarily proprioceptive adaptation, but visual adaptation was also present. The third condition produced primarily visual adaptation. Results are discussed in terms of two possible roles for the auditory signal: (i) a rhythmic auditory signal may enhance overall activation of the adaptive neural network; and (ii) movement synchronization with a rhythmic auditory signal may enable multisensory integration, including auditory spatial information that selects the more reliable proprioceptive signal for movement control. Consequently, detection of the misalignment is localized and realignment occurs in the visual system.