From retina to cognition: How does macular degeneration affect visual cognition?
The loss of foveal vision is a dramatic incision not only for the affected patients, but also for the visual system itself. As a reaction to the loss of the area of best vision, processes of reorganization have to take action in order to reduce the impairment of visual and cognitive capacities. Specifically, the formation of a new preferred retinal locus of fixation demands the accommodation of fixation-strategies, eye-movement programming, covert and overt exploration of the visual space, of of reading and visual search, and of mechanisms underlying visual object recognition and memory. In this joint project we aim at a detailed description of the retinal damage and its consequences on spatio-temporal cortical input and then investigate how higher visual and cognitive functions are adapted to the new situation to retain the visual and cognitive functionality of the system. The research project is designed to enhance our understanding of plastic processes of the visual system and is also of clinical relevance as maculopathies, in particular age-related macular degeneration (AMD), are the leading cause of legal blindness in Western nations.
The core aspect is to investigate which consequences a macular pathology bears on high-level aspects of vision, such as visual search, reading, deployment of visual attention and visual learning. As detailed in the sub-projects, we believe that a macular pathology does not only lead to basic visual deficits such as visual field defects and loss of acuity, but also to impairments in the guidance of eye-movements as well as of covert attention, in the distribution of spatial attention across the visual field and in the ability to use regularities in the visual environment to guide the exploration of our surroundings.
To address these topics, we intend to use a range of methods from sensory physiology, over reaction time and eye-movement analyses and mathematical modelling to functional magnetic resonance imaging (fMRI). These methods will be used in concert to follow the path of visual cognition from retinal pathology to subsequent visual processing changes and concomitant cortical activation changes.
- The first subproject (Hoffmann) will yield a detailed description of the visual field sensitivities of AMD-patients derived from objective retinal and cortical correlates of visual function and from subjective perimetric measurements. Specifically, recordings of electroretinograms and visual evoked cortical potentials will be performed using the novel multifocal stimulation technique to assess the visual field topography of retinal and cortical signals. This may not only help to uncover to date unidentified aspects of the pathophysiology underlying AMD, but will also yield a comprehensive account of the changes to the cortical input and to the visual field sensitivity of the investigated individuals. This will serve as an ideal basis of subprojects 2 and 3, which investigate active vision.
- The second subproject (Müller-Plath and Engbert) investigates cognitive subprocesses of visual search and reading. Visual search and reading both involve complex interactions of visuospatial attentional and other cognitive processes. The project will elucidate the impact of macular pathology on these processes by the collection of psychophysical and eye-movement data and the mathematical modelling of these data. These analyses will lead to the development of training programs, whose efficiency will be tested. In addition, modelling will be used to relate deficits in active vision to the electrophysiological and fMRI results obtained in subprojects 1 and 3.
- The third subproject (Pollmann) aims at elucidating changes in the interaction of visual attention and visual learning and visual object memory. Visual attention and visual learning interact in that deployment of attention is often a prerequisite of learning. Conversely, memory can guide the deployment of attention, e.g. in contexts or scenes that have been seen before, but also in the search for specific objects. Loss of foveal vision due to macular degeneration may severely change the deployment of attention. This project will use behavioural and eye-movement measures to characterize these changes. It will combine these measures with fMRI-experiments to elucidate changes in cortical involvement which go along with process changes. These data will be related to the retinal pathology investigated in the first and the process analyses delivered by the third subproject.
Prof. Dr. Stefan Pollmann
Institut für Psychologie II, Lehrstuhl für Allgemeine Psychologie
PD Dr. Michael Hoffmann
Sektion für Klin. und Exp. Sinnesphysiologie
Prof. Dr. Gisela Müller-Plath
Institut für Psychologie und Arbeitswissenschaft
Psychologie Neuer Medien und Methodenlehre
Prof. Dr. Ralf Engbert
Institut für Psychologie, Allgemeine und Biologische Psychologie
Geringswald, F., Baumgartner, F. & Pollmann, S. (2012). Simulated loss of foveal vision eliminates visual search advantage in repeated displays. Frontiers in Human Neuroscience, 6, 134.
Geringswald F., Baumgartner F.J., Pollmann S. (2013). A behavioral task for the validation of a gaze-contingent simulated scotoma. Behavioral Research Methods, Mar 23. [Epub ahead of print].
Geringswald, F., Herbik, A., Hoffmann, M.B. & Pollmann, S. (2013). Contextual cueing impairment in patients with Age-Related Macular Degeneration. Journal of Vision, 13(3), 28; doi:10.1167/13.3.28
Herbik, A., Hölzl, C.G., Reupsch, J., Hoffmann, M.B. (2013). Differential effects of optic media opacities on mfERGs and mfVEPs. Clinical Neurophysiology 124, 1225-1231.
Geringswald, F., Herbik, A., Hofmüller, W., Hoffmann, M.B. & Pollmann, S. (2015). Visual memory for objects following foveal vision loss. Journal of Experimental Psychology: Learning, Memory, and Cognition, 41, 1471-1484.
Geringswald, F., & Pollmann, S. (2015). Central and peripheral vision loss differentially affects contextual cueing in visual search. Journal of Experimental Psychology: Learning, Memory, and Cognition, 41, 1485-1496.
Geringswald, F., Porracin, E. & Pollmann, S. (2016). Impairment of visual memory for objects in natural scenes by simulated central scotomata. Journal of Vision, 16, 6, 1-12.
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