Forward optic flow is prioritised in visual awareness independently of walking direction

When two different images are presented separately to each eye, one experiences smooth transitions between them-a phenomenon called binocular rivalry. Previous studies have shown that exposure to signals from other senses can enhance the access of stimulation-congruent images to conscious perception. However, despite our ability to infer perceptual consequences from bodily movements, evidence that action can have an analogous influence on visual awareness is scarce and mainly limited to hand movements. Here, we investigated whether one's direction of locomotion affects perceptual access to optic flow patterns during binocular rivalry. Participants walked forwards and backwards on a treadmill while viewing highly-realistic visualisations of self-motion in a virtual environment. We hypothesised that visualisations congruent with walking direction would predominate in visual awareness over incongruent ones, and that this effect would increase with the precision of one's active proprioception. These predictions were not confirmed: optic flow consistent with forward locomotion was prioritised in visual awareness independently of walking direction and proprioceptive abilities. Our findings suggest the limited role of kinaesthetic-proprioceptive information in disambiguating visually perceived direction of self-motion and indicate that vision might be tuned to the (expanding) optic flow patterns prevalent in everyday life

The contemporary model of vertebral column joint dysfunction and impact of high-velocity, low-amplitude controlled vertebral thrusts on neuromuscular function

Peer reviewedPublisher PD

Sensory Processing and Movement Control in Children

Movement control and motor learning depend largely on sensory processing (SP) of different sensory inputs in order to make a relevant perceptual decision that can be expressed as a coordinated and goal-directed movement. The aim of this thesis is to explore the role of SP on perceptual decision-making, movement control and participation among children. The first study aimed to identify and summarise the role of SP on movement abilities among children with movement difficulties, particularly developmental coordination disorder (DCD), through a systematic review. This is due to the literature being replete with studies investigating the role of SP on movement among children with DCD, however, no updated systematic review to synthesise the findings has been published. Furthermore, because there is a paucity of empirical studies considering SP abilities in the context of the relationship between movement control, levels of and preferences for physical activity (PA) among children, the second study aimed to explore the relationship between them using four valid questionnaires. Finally, as limited research was found in the empirical literature that had investigated the effect of multisensory inputs on perceptual decision-making among children, the third study aimed to investigate the effect of multisensory versus unisensory stimuli on two elements contributing to perceptual decision-making (reaction time (RT) and accuracy). The first study showed that the various dimensions of SP significantly contribute to movement abilities in DCD. Moreover, the second study showed that movement abilities, levels of and preferences for PA may be influenced by SP abilities among children. Lastly, the third study showed that multisensory stimuli may enhance the process of decision-making, however, this was found to be more pronounced in older children. These results show clear evidence of the role of SP on movement and emphasise the importance of addressing SP abilities in assessments and intervention programmes

A modular theory of multisensory integration for motor control

To control targeted movements, such as reaching to grasp an object or hammering a nail, the brain can use divers sources of sensory information, such as vision and proprioception. Although a variety of studies have shown that sensory signals are optimally combined according to principles of maximum likelihood, increasing evidence indicates that the CNS does not compute a single, optimal estimation of the target's position to be compared with a single optimal estimation of the hand. Rather, it employs a more modular approach in which the overall behavior is built by computing multiple concurrent comparisons carried out simultaneously in a number of different reference frames. The results of these individual comparisons are then optimally combined in order to drive the hand. In this article we examine at a computational level two formulations of concurrent models for sensory integration and compare this to the more conventional model of converging multi-sensory signals. Through a review of published studies, both our own and those performed by others, we produce evidence favoring the concurrent formulations. We then examine in detail the effects of additive signal noise as information flows through the sensorimotor system. By taking into account the noise added by sensorimotor transformations, one can explain why the CNS may shift its reliance on one sensory modality toward a greater reliance on another and investigate under what conditions those sensory transformations occur. Careful consideration of how transformed signals will co-vary with the original source also provides insight into how the CNS chooses one sensory modality over another. These concepts can be used to explain why the CNS might, for instance, create a visual representation of a task that is otherwise limited to the kinesthetic domain (e.g., pointing with one hand to a finger on the other) and why the CNS might choose to recode sensory information in an external reference frame