Spatial localization investigated by continuous pointing during visual and gravitoinertial changes

• Published in: Experimental brain research 2011-12, Vol.215 (3-4), p.173-182
• Main Authors: Scotto Di Cesare, C., Bringoux, L., Bourdin, C., Sarlegna, F. R., Mestre, D. R.
• Format: Article
• Language: English
• Subjects: Adult; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Centrifugation; Cognitive Sciences; Environmental changes; Eye and associated structures. Visual pathways and centers. Vision; Female; Fundamental and applied biological sciences. Psychology; Gravity Sensing - physiology; Humans; Illusions - physiology; Life Sciences; Localization; Male; Medical sciences; Motion Perception - physiology; Nervous system (semeiology, syndromes); Nervous system as a whole; Neurology; Neurons and Cognition; Neurosciences; Perceptions; Perceptual-motor processes; Physiological aspects; Psychomotor Performance - physiology; Research Article; Sensory integration; Space Perception - physiology; spatial discrimination; Vertebrates: nervous system and sense organs; Vestibular system; Visual perception; Visual stimuli; Young Adult
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/s00221-011-2884-8

In order to accurately localize an object, human observers must integrate multiple sensory cues related to the environment and/or to the body. Such multisensory integration must be repeated over time, so that spatial localization is constantly updated according to environmental changes. In the present experimental study, we examined the multisensory integration processes underlying spatial updating by investigating how gradual modifications of gravitoinertial cues (i.e., somatosensory and vestibular cues) and visual cues affect target localization skills. These were assessed by using a continuous pointing task toward a body-fixed visual target. The “single” rotation of the gravitoinertial vector (produced by off-axis centrifugation) resulted in downward pointing errors, which likely were related to a combination of oculogravic and somatogravic illusions. The “single” downward pitch rotation of the visual background produced an elevation of the arm relative to the visual target, suggesting that the rotation of the visual background caused an illusory target elevation (induced-motion phenomenon). Strikingly, the errors observed during the “combined” rotation of the visual background and of the gravitoinertial vector appeared as a linear combination of the errors independently observed during “single” rotations. In other words, the centrifugation effect on target localization was reduced by the visual background rotation. The observed linear combination indicates that the weights of visual and gravitoinertial cues were similar and remained constant throughout the stimulation.