Spatiotemporal response analysis to simple and complex stimuli in patients with unilateral spatial neglect: 3D verification using immersive virtual reality

Unilateral spatial neglect (USN) occurs as a sequela of stroke. This study proposes a neglect-identification system to evaluate the ability of patients with USN to process higher-order information. The measurement is done by varying the complexity of stimuli presented in an immersive virtual-reality space. Clinical study was conducted on three patients with USN using the new system, and the results showed that the USN patients were able to recognize simple presented objects, but neglected complex presented objects on the neglected side. The difference in reaction time between complex and simple presented objects was compared, and it was found that there was a delay in the neglected side, assumed to be a delay in higher-order information processing. The time lapse from stimulus presentation to recognition is divided into search and recognition time, and the cause of the degradation in higher-order information processing is clarified based on eye movement during recognition time. Furthermore, quantifying the ability to process high-order information using the proposed higher-order information-processing (HoIP) index shows that this ability deteriorates spatially and in the neglected area.Clinical Relevance— The system developed in this study should provide efficient rehabilitation for each patient because it can evaluate the patient’s ability to process higher-order information in a three-dimensional space.