The Neural Correlates of Vection: An fMRI Study

Vection is an illusion of visually-induced self-motion in a stationary observer. I used different types of vection stimuli in a functional magnetic resonance imaging (fMRI) study to determine the interaction between cortical visual regions and cortical vestibular regions during vection. My findings suggest that the cingulate sulcus visual area is heavily involved in self-motion processing. The parieto-insular vestibular cortex, showed a significant change in blood oxygenation level dependent signal activity during vection but to a lesser extent than CSv. Behavioural data correlated with the neuroimaging data (in CSv and PIVC) as both show a significant difference when comparing the radial oscillating condition to the radial smooth condition in CSv and PIVC - suggesting a neural correlate of the jitter effect. My results suggest that the brain region of primary importance in the self-motion debate is CSv - a region that has received little attention in the vection literature to date

Чинники, що спричиняють кіберхвороби

The section discusses factors impacting cybersickness.У розділі розглянуто чинники, що спричиняють кіберхвороби

Cortical Correlates of the Simulated Viewpoint Oscillation Advantage for Vection

Behavioural studies have consistently found stronger vection responses for oscillating, compared to smooth/constant, patterns of radial flow (the simulated viewpoint oscillation advantage for vection). Traditional accounts predict that simulated viewpoint oscillation should impair vection by increasing visual-vestibular conflicts in stationary observers (as this visual oscillation simulates self-accelerations that should strongly stimulate the vestibular apparatus). However, support for increased vestibular activity during accelerating vection has been mixed in the brain imaging literature. This fMRI study examined BOLD activity in visual (cingulate sulcus visual area - CSv; medial temporal complex - MT+; V6; precuneus motion area - PcM) and vestibular regions (parieto-insular vestibular cortex - PIVC/posterior insular cortex - PIC; ventral intraparietal region - VIP) when stationary observers were exposed to vection-inducing optic flow (i.e., globally coherent oscillating and smooth self-motion displays) as well as two suitable control displays. In line with earlier studies in which no vection occurred, CSv and PIVC/PIC both showed significantly increased BOLD activity during oscillating global motion compared to the other motion conditions (although this effect was found for fewer subjects in PIVC/PIC). The increase in BOLD activity in PIVC/PIC during prolonged exposure to the oscillating (compared to smooth) patterns of global optical flow appears consistent with vestibular facilitation

PERCEPTION OF SMOOTH AND PERTURBED VECTION IN SHORT-DURATION MICROGRAVITY

Successful adaptation to the microgravity environment of space and re-adaptation to gravity on earth requires recalibration of visual and vestibular signals. Recently, we have shown that adding simulated viewpoint oscillation to visual self-motion displays produces more compelling vection (despite the expected increase in visual-vestibular conflict experienced by stationary observers). Currently it is unclear what role adaptation to gravity might play in this oscillation based vection advantage. The vection elicited by optic-flow displays simulating either smooth forward motion or forward motion perturbed by viewpoint oscillation was assessed before, during and after microgravity exposure in parabolic flight. During normal 1-g conditions subjects experienced significantly stronger vection for oscillating compared to smooth radial optic flow. The magnitude of this oscillation enhancement was reduced during short-term microgravity exposure, more so for simulated interaural (as opposed to spinal) axis viewpoint oscillation. We also noted a small overall reduction in vection sensitivity post-flight. A supplementary experiment found that 1-g vection responses did not vary significantly across multiple testing sessions. These findings: (i) demonstrate that the oscillation advantage for vection is very stable and repeatable during 1-g conditions, and (ii) imply that adaptation or conditioned responses played a role in the post-flight vection reductions. The effects observed in microgravity are discussed in terms of the ecology of terrestrial locomotion and the nature of movement in microgravity

Perception of smooth and perturbed vection in short-duration microgravity

Successful adaptation to the microgravity environment of space and readaptation to gravity on earth requires recalibration of visual and vestibular signals. Recently, we have shown that adding simulated viewpoint oscillation to visual self-motion displays produces more compelling vection (despite the expected increase in visualvestibular conflict experienced by stationary observers). Currently, it is unclear what role adaptation to gravity might play in this oscillation-based vection advantage. The vection elicited by optic flow displays simulating either smooth forward motion or forward motion perturbed by viewpoint oscillation was assessed before, during and after microgravity exposure in parabolic flight. During normal 1-g conditions subjects experienced significantly stronger vection for oscillating compared to smooth radial optic flow. The magnitude of this oscillation enhancement was reduced during short-term microgravity exposure, more so for simulated interaural (as opposed to spinal) axis viewpoint oscillation. We also noted a small overall reduction in vection sensitivity post-flight. A supplementary experiment found that 1-g vection responses did not vary significantly across multiple testing sessions. These findings: (i) demonstrate that the oscillation advantage for vection is very stable and repeatable during 1-g conditions and (ii) imply that adaptation or conditioned responses played a role in the post-flight vection reductions. The effects observed in microgravity are discussed in terms of the ecology of terrestrial locomotion and the nature of movement in microgravity