Abstract
The objective of this research is to increase our understanding of the effects that virtual reality (VR) has on robotic laparoscopy and gait with a special interest in variability. In the first experiment, two tasks that required bimanual coordination were chosen to mimic actual surgical tasks used during a robotic-assisted laparoscopic surgery. The outcome of this experiment showed that well designed VR simulators can replicate the physiological and mechanical demands of actual surgical tasks, which is extremely important in terms of learning and practicing for new robotic-assisted surgeons. In the second experiment, healthy adults were asked to walk forward (FW) and backward (BW) in a VR environment while the direction of the optic flow was either in line or opposite to the direction of walking. Significant differences were demonstrated between the FW and the BW gait characteristics as well as in the magnitude and structure of gait variability. No significant differences were found among the BW conditions as a result of the direction of visual cues. In order to get optimal benefit of BW in the aged and the diseased, optical flow of visual feedback may need to be manipulated in a different manner than FW. Lastly, in the third experiment, we investigated the effect of the velocity of optic flow on the amount and structure of forward walking variability. Linear measures of variability did not show significant differences between Non-VR and VR conditions while nonlinear measures identified significant differences at the hip, ankle, and in stride interval. In response to manipulation of the optic flow, few significant differences were observed between the three virtual conditions in the following order: normal > fast > slow. Measures of structure of variability are more sensitive to changes in gait due to manipulation of visual cues, whereas measures of the amount of variability may be concealed by adaptive mechanisms. Visual cues increase the complexity of gait variability and may increase the degrees of freedom available to the subject. Further exploration of the effects of optic flow manipulation on locomotion may provide us with an effective tool for rehabilitation of subjects with sensorimotor issues.