title: Nonlinear population receptive field changes in human area V5/MT+ of healthy subjects with simulated visual field scotomas.
abstract: There is extensive controversy over whether the adult visual cortex is able to reorganize following visual field loss (scotoma) as a result of retinal or cortical lesions. Functional magnetic resonance imaging (fMRI) methods provide a useful tool to study the aggregate receptive field properties and assess the capacity of the human visual cortex to reorganize following injury. However, these methods are prone to biases near the boundaries of the scotoma. Retinotopic changes resembling reorganization have been observed in the early visual cortex of normal subjects when the visual stimulus is masked to simulate retinal or cortical scotomas. It is not known how the receptive fields of higher visual areas, like hV5/MT+, are affected by partial stimulus deprivation. We measured population receptive field (pRF) responses in human area V5/MT+ of 5 healthy participants under full stimulation and compared them with responses obtained from the same area while masking the left superior quadrant of the visual field ("artificial scotoma" or AS). We found that pRF estimations in area hV5/MT+ are nonlinearly affected by the AS. Specifically, pRF centers shift towards the AS, while the pRF amplitude increases and the pRF size decreases near the AS border. The observed pRF changes do not reflect reorganization but reveal important properties of normal visual processing under different test-stimulus conditions.
authors.affiliation: Max Planck Institute for Biological Cybernetics, Spemannstr. 38, 72076 Tuebingen, Germany; Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA; Graduate School of Neural and Behavioural Sciences, International Max Planck Research School, Tuebingen, Germany. Electronic address: amalia.papanikolaou@tuebingen.mpg.de.
authors.forename: Amalia
authors.initials: A
authors.lastname: Papanikolaou
authors.affiliation: Max Planck Institute for Biological Cybernetics, Spemannstr. 38, 72076 Tuebingen, Germany; Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium; Bernstein Center for Computational Neuroscience, Tuebingen, Germany. Electronic address: georgios.keliris@tuebingen.mpg.de.
authors.forename: Georgios A
authors.initials: GA
authors.lastname: Keliris
authors.affiliation: Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Sangkyun
authors.initials: S
authors.lastname: Lee
authors.affiliation: Max Planck Institute for Biological Cybernetics, Spemannstr. 38, 72076 Tuebingen, Germany; Division of Imaging Science and Biomedical Engineering, University of Manchester, Manchester M13 9PT, UK.
authors.forename: Nikos K
authors.initials: NK
authors.lastname: Logothetis
authors.affiliation: Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA. Electronic address: ssmirnakis@cns.bcm.edu.
authors.forename: Stelios M
authors.initials: SM
authors.lastname: Smirnakis
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010364:Pattern Recognition, Visual / Q000502:physiology*; D012607:Scotoma / Q000503:physiopathology*; D014793:Visual Cortex / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*; D055815:Young Adult
keywords: Artificial scotoma; Reorganization; fMRI; hV5/MT+