Altered visual population receptive fields in human albinism.
Ivan Alvarez, Rebecca Smittenaar, Sian E Handley, Alki Liasis, Martin I Sereno, D Samuel Schwarzkopf, Chris A Clark
Author Information
Ivan Alvarez: Institute of Child Health, University College London, London, UK; Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, USA. Electronic address: ivanalvarez@berkeley.edu.
Rebecca Smittenaar: Experimental Psychology, University College London, London, UK.
Sian E Handley: Institute of Child Health, University College London, London, UK; Department of Ophthalmology, Great Ormond Street Hospital for Children, London, UK.
Alki Liasis: Institute of Child Health, University College London, London, UK; Department of Ophthalmology, Great Ormond Street Hospital for Children, London, UK; Department of Ophthalmology, UPMC Children's Hospital, Pittsburgh, USA.
Martin I Sereno: Experimental Psychology, University College London, London, UK; Department of Psychological Sciences, Birkbeck/UCL Centre for NeuroImaging (BUCNI), Birkbeck College, University of London, London, UK; Department of Psychology, San Diego State University, San Diego, USA.
D Samuel Schwarzkopf: Experimental Psychology, University College London, London, UK; Institute of Cognitive Neuroscience, University College London, London, UK; School of Optometry & Vision Science, University of Auckland, Auckland, New Zealand.
Chris A Clark: Institute of Child Health, University College London, London, UK.
Albinism is a congenital disorder where misrouting of the optic nerves at the chiasm gives rise to abnormal visual field representations in occipital cortex. In typical human development, the left occipital cortex receives retinal input predominantly from the right visual field, and vice-versa. In albinism, there is a more complete decussation of optic nerve fibers at the chiasm, resulting in partial representation of the temporal hemiretina (ipsilateral visual field) in the contralateral hemisphere. In this study, we characterize the receptive field properties for these abnormal representations by conducting detailed fMRI population receptive field mapping in a rare subset of participants with albinism and no ocular nystagmus. We find a nasal bias for receptive field positions in the abnormal temporal hemiretina representation. In addition, by modelling responses to bilateral visual field stimulation in the overlap zone, we found evidence in favor of discrete unilateral receptive fields, suggesting a conservative pattern of spatial selectivity in the presence of abnormal retinal input.
