Contribution of sensory memory to speech motor learning

Speech learning requires precise motor control but it likewise requires transient storage of information to enable the adjustment of upcoming movements based on the success or failure of previous attempts. The contribution of somatic sensory memory for limb position has been documented in work on arm movement, however, in speech, the sensory support for speech production comes both from somatosensory and auditory inputs and accordingly sensory memory for either or both of sounds and somatic inputs might contribute to learning. In the present study, adaptation to altered auditory feedback was used as an experimental model of speech motor learning. Participants also underwent tests of both auditory and somatic sensory memory. We found that although auditory memory for speech sounds is better than somatic memory for speech-like facial skin deformations, somatic sensory memory predicts adaptation, whereas auditory sensory memory does not. Thus, even though speech relies substantially on auditory inputs and in the present manipulation adaptation requires the minimization of auditory error, it is somatic inputs that provide the memory support for learning.