| Abstract | Interactions between auditory and somatosensory
information are relevant to the neural processing of
speech since speech processes and certainly speech production involves
both auditory information and inputs that arise from the
muscles and tissues of the vocal tract. We previously demonstrated
that somatosensory inputs associated with facial skin deformation
alter the perceptual processing of speech sounds. We show here that
the reverse is also true, that speech sounds alter the perception of
facial somatosensory inputs. As a somatosensory task, we used a
robotic device to create patterns of facial skin deformation that would
normally accompany speech production. We found that the perception
of the facial skin deformation was altered by speech sounds in a
manner that reflects the way in which auditory and somatosensory
effects are linked in speech production. The modulation of orofacial
somatosensory processing by auditory inputs was specific to speech
and likewise to facial skin deformation. Somatosensory judgments
were not affected when the skin deformation was delivered to the
forearm or palm or when the facial skin deformation accompanied
nonspeech sounds. The perceptual modulation that we observed in
conjunction with speech sounds shows that speech sounds specifically
affect neural processing in the facial somatosensory system and
suggest the involvement of the somatosensory system in both the
production and perceptual processing of speech. |