Triple visual hemifield maps in a case of optic chiasm hypoplasia
Khazar Ahmadi,
Alessio Fracasso,
Robert J. Puzniak,
Andre D. Gouws,
Renat Yakupov,
Oliver Speck,
Joern Kaufmann,
Franco Pestilli,
Serge O. Dumoulin,
Antony B. Morland,
Michael B. Hoffmann
Affiliations
Khazar Ahmadi
Department of Ophthalmology, Otto-von-Guericke University, Magdeburg, 39120, Germany; Clinical Memory Research Unit, Department of Clinical Sciences, Lund University, Lund, 22362, Sweden
Alessio Fracasso
Department of Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, 3584 CS, the Netherlands; Department of Radiology, University Medical Center Utrecht, Utrecht, 3584 CX, the Netherlands; Spinoza Centre for Neuroimaging, Amsterdam, 1105 BK, the Netherlands; Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, G12 8QB, UK
Robert J. Puzniak
Department of Ophthalmology, Otto-von-Guericke University, Magdeburg, 39120, Germany
Andre D. Gouws
Department of Psychology, York Neuroimaging Centre, University of York, York, YO10 5NY, UK
Renat Yakupov
Department of Biomedical Magnetic Resonance, Institute for Physics, Otto-von-Guericke University, Magdeburg, 39120, Germany; German Center for Neurodegenerative Diseases, Magdeburg, 39120, Germany
Oliver Speck
Department of Biomedical Magnetic Resonance, Institute for Physics, Otto-von-Guericke University, Magdeburg, 39120, Germany; German Center for Neurodegenerative Diseases, Magdeburg, 39120, Germany; Leibniz Institute for Neurobiology, Magdeburg, 39118, Germany; Center for Behavioral Brain Sciences, Magdeburg, 39106, Germany
Joern Kaufmann
Department of Neurology, Otto-von-Guericke-University, Magdeburg, 39120, Germany
Franco Pestilli
Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 1101 E, USA
Serge O. Dumoulin
Department of Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, 3584 CS, the Netherlands; Spinoza Centre for Neuroimaging, Amsterdam, 1105 BK, the Netherlands; Department of Experimental and Applied Psychology, VU University Amsterdam, Amsterdam, 1081 BT, the Netherlands
Antony B. Morland
Department of Psychology, York Neuroimaging Centre, University of York, York, YO10 5NY, UK; Centre for Neuroscience, Hull-York Medical School, University of York, York, YO10 5DD, UK
Michael B. Hoffmann
Department of Ophthalmology, Otto-von-Guericke University, Magdeburg, 39120, Germany; Center for Behavioral Brain Sciences, Magdeburg, 39106, Germany; Corresponding author. Department of Ophthalmology, Otto-von-Guericke University, Leipziger Str. 44, 39120, Magdeburg, Germany.
In humans, each hemisphere comprises an overlay of two visuotopic maps of the contralateral visual field, one from each eye. Is the capacity of the visual cortex limited to these two maps or are plastic mechanisms available to host more maps? We determined the cortical organization of the visual field maps in a rare individual with chiasma hypoplasia, where visual cortex plasticity is challenged to accommodate three hemifield maps. Using high-resolution fMRI at 7T and diffusion-weighted MRI at 3T, we found three hemiretinal inputs, instead of the normal two, to converge onto the left hemisphere. fMRI-based population receptive field mapping of the left V1–V3 at 3T revealed three superimposed hemifield representations in the left visual cortex, i.e. two representations of opposing visual hemifields from the left eye and one right hemifield representation from the right eye. We conclude that developmental plasticity including the re-wiring of local intra- and cortico-cortical connections is pivotal to support the coexistence and functioning of three hemifield maps within one hemisphere.
