Discoveries

PLATYPUS researchers started work in July 2017. We focus on several research questions as outlined below. Updates and progress will also be posted here as we make new discoveries.

Spatial maps for action in the primate visual brain
Visual spatial maps in the brain serve different perceptual and behavioral purposes. Properties of these maps and the relationships between them in single species and between different species are still under question. Our first objective is to bring together the viewpoints obtained from studying different animal species and behaviors with complementary experimental and theoretical techniques. We will further investigate how these maps combine visual input with eye movement information that can be used to guide reaching movements and to distinguish external from self generated visual motion. We will then study plastic changes in this representation by using adaptation of eye position and determine its consequence on spatial behavior.

A gap in the map: the blind spot
The blind spot provides one of the clearest and simplest examples of the difference between physical and perceptual space. It is an area of the retina that cannot receive any visual input, yet we do not experience a gap in perception due to filled-in contextual information from around its border. While a considerable number of studies have investigated the properties of filling-in concerning texture or object-related, i.e. ventral stream properties, it is remarkable that its spatial aspects, are largely unknown. For the present proposal, the blind spot provides a convenient way to test core principles of the dynamics and adaptive processes in motor-related spatial vision, our second objective. The results and the developed paradigms from this research will later be applied to the study of (artificial) scotomas using virtual reality simulations.

Oculomotor plasticity effects on visual space
Perceptual space is tightly linked to eye movements. Trans-saccadic changes of target position lead to adaptation of eye movements and concomitant changes of perceived location. Our third objective is to understand how changing a motor representation is linked to changes in visual space. We will study whether spatial plasticity is driven directly by the motor adaptation or whether it is a consequence of the change of the visual scene that is masked by saccadic suppression. We will furthermore investigate whether similar plastic effects occur for blinks, which constitute a different type of interruption of the visual input but share some mechanisms with saccades. We will then search for the physiological basis of the adaptation-induced changes to spatial perception. The developed paradigms will be used for translational approaches, i.e. they will be applied to study perceptual and motor changes in conjunction with progressive additional lenses.

Plasticity of spatial geometry
Spatial vision is not only about location but also about geometry, i.e. the shapes formed by locations that belong together. This is especially important for reaching movements towards objects but also for the perception of the size and shape of objects. Size perception in the periphery is plastic in that it changes after trans-saccadic changes of object size. Our fourth objective is to understand how changes in spatial or motor coordinates translate into changes in perceived geometry. We will investigate changes to object perception induced by changes of haptic feedback during a reaching movement and by changes of visual feedback after a saccade. Progressive additional lenses introduce different geometric distortions in different parts of the visual field, producing a direct coupling between eye position and size perception. We will study the implications of this coupling for applications in wearers of progressive additional lenses

 

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