Retinal diseases such as macular degeneration usually lead to central vision loss, making the affected patients dependent on their peripheral residual vision. Often a kind of pseudo fovea (preferred retinal locus, PRL) develops in the peripheral visual field, which is then used in everyday life for the fixation of objects or faces, as well as for reading. These long-term adaptation processes are accompanied by certain neuroplastic changes in the visual cortex of the affected patients. Furthermore, appropriate training protocols, such as visual perceptual learning tasks, can help to further improve peripheral visual performance and even trigger neuronal plasticity. Our goal in this planned project is to investigate how these two neuroplastic processes of long-term adaptation and training act together and to uncover possible interrelations between the two. For this purpose, visual perceptual learning in the peripheral visual field will be applied, and it will be examined to what extent the learning success at the PRL of patients with central vision loss will be different from the learning success at a comparable peripheral site in the opposite visual hemifield (OppPRL) and from the learning success of normally sighted control persons, who are trained in the same visual task. The training measures will be accompanied by (functional) magnetic resonance imaging (fMRI) to reveal the neural correlates of learning in the visual cortex. Additionally, the biochemical changes caused by learning will be determined by magnetic resonance spectroscopy (MRS). To investigate possible changes in the cortical macro- and microstructure in grey and white matter of the visual cortex, structural and diffusion-weighted MRI will be performed. These measures will provide us with a more comprehensive picture of long and short term neuroplastic adaptation processes in patients with central vision loss and thus help to design even more efficient training protocols.
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