title: Dissociations in Coherence Sensitivity Reveal Atypical Development of Cortical Visual Processing in Congenital Achromatopsia.
abstract: OBJECTIVE
  While basic visual functions have been described in subjects with congenital achromatopsia (ACHM), little is known about their mid- or high-level cortical visual processing. We compared midlevel cortical visual processing in ACHM subjects (n = 11) and controls (n = 20).
  
  
  METHODS
  Abilities to detect global form, global motion, and biological motion embedded in noise were tested across a range of light levels, including scotopic, in which both ACHM subjects and controls must rely on rods. Contrast sensitivity functions (CSFs) were also measured.
  
  
  RESULTS
  Achromatopsia subjects showed differential impairments across tests. In scotopic conditions, global form was most impaired, while biological motion was normal. In a subset of three ACHM subjects with normal scotopic CSFs, two of the three showed global form perception worse than controls; all showed global motion comparable to controls; and strikingly, two of the three showed biological motion perception superior to controls.
  
  
  CONCLUSIONS
  The cone signal appears to play a crucial role in the development of perception of global form, as in ACHM this is impaired even in scotopic conditions, in which controls also have to rely on rods, and even in ACHM subjects with no scotopic spatial vision loss. In contrast, the rod signal appears sufficient for the development of normal (or even superior) extrastriate biological motion perception. These results suggest that ACHM leads to atypical development of cortical vision, highlighting the need to better understand the potential for further reorganization of cortical visual processing following new therapies aimed at restoring cone function.
authors.affiliation: Institute of Ophthalmology, University College London, London, United Kingdom.
authors.forename: Eliza
authors.initials: E
authors.lastname: Burton
authors.affiliation: Division of Psychology and Language Sciences, University College London, London, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Wattam-Bell
authors.affiliation: Institute of Ophthalmology, University College London, London, United Kingdom.
authors.forename: Gary
authors.initials: G
authors.lastname: S Rubin
authors.affiliation: Institute of Ophthalmology, University College London, London, United Kingdom 3Moorfields Eye Hospital, London, United Kingdom.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Aboshiha
authors.affiliation: Institute of Ophthalmology, University College London, London, United Kingdom 3Moorfields Eye Hospital, London, United Kingdom.
authors.forename: Michel
authors.initials: M
authors.lastname: Michaelides
authors.affiliation: Division of Psychology and Language Sciences, University College London, London, United Kingdom 4Experimental Psychology, University of Oxford, Oxford, United Kingdom.
authors.forename: Janette
authors.initials: J
authors.lastname: Atkinson
authors.affiliation: Experimental Psychology, University of Oxford, Oxford, United Kingdom.
authors.forename: Oliver
authors.initials: O
authors.lastname: Braddick
authors.affiliation: Institute of Ophthalmology, University College London, London, United Kingdom 5Department of Psychology, Durham University, Durham, United Kingdom.
authors.forename: Marko
authors.initials: M
authors.lastname: Nardini
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003117:Color Vision Defects / Q000151:congenital* / Q000503:physiopathology; D015350:Contrast Sensitivity / Q000502:physiology; D005260:Female; D005556:Form Perception / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009039:Motion Perception / Q000502:physiology; D010775:Photic Stimulation; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult