Examining the Sensorimotor Integration Processes Prior to and During Movements to Somatosensory Targets

Previous research on multisensory integration for movement planning and control has focused on movements to targets external to the body. In this dissertation, three experiments were conducted to examine the sensorimotor transformation processes underlying goal-directed actions to targets defined by body positions (i.e., somatosensory targets). The goal of the first experiment was to investigate if the modality of the cue used to indicate the location of a somatosensory target affects the body representation used to encode the target’s position during movement planning. The results showed that auditory cues prompted the use of an exteroceptive body representation for the encoding of movements to a somatosensory target in visual coordinates. The goal of the second experiment was to examine the neural processes associated with the visual remapping of an auditory-cued somatosensory target. It was found that the sensorimotor transformation processes responsible for the conversion of a somatosensory target position into visual coordinates engages visuomotor cortical networks to a greater extent than movements to external visual targets. The goal of the third experiment was to examine the sensorimotor transformation processes employed for the online control of movements to a somatosensory target. The results of this experiment revealed that the remapping of a somatosensory target into visual coordinates may not occur prior to online corrections. Altogether the findings of this thesis reveal that sensory cues can facilitate the remapping of a somatosensory target prior to goal-directed actions. However, these remapping processes may be too costly for use during online control when there is no vision of the reaching limb.Ph.D