title: Visually-based temporal distortion in dyslexia.
abstract: In this study, we show that invisible flicker adaptation reduces the perceived duration of a subsequently viewed stimulus in control subjects, but not in dyslexics. Dyslexics, like controls, show apparent duration compression after 20Hz flicker and show normal shifts in apparent temporal frequency after adaptation. However a subgroup of the test group, scoring low on both a test of phonological skill (spoonerisms) and a test of literacy (NART), show an apparent temporal expansion after 5Hz flicker adaptation, a finding not previously seen in controls. Recent studies have linked genes conferring susceptibility to a cluster of language and sensory deficits to anomalous neural migration, providing a tentative biological basis for dyslexia. However it has proved difficult to establish a clear link between sensory deficits and impaired reading. The results presented here point to an abnormal adaptation response within the early precortical stages of the magnocellular pathway, occurring in tandem with a deficit in word-level cognitive processing, providing psychophysical evidence for anomalous cortico-thalamic circuits in dyslexia.
authors.affiliation: Department of Psychology, University College London, Gower Street, London WC1E 6BT, UK. a.johnston@ucl.ac.uk
authors.forename: Alan
authors.initials: A
authors.lastname: Johnston
authors.forename: Aurelio
authors.initials: A
authors.lastname: Bruno
authors.forename: Junji
authors.initials: J
authors.lastname: Watanabe
authors.forename: Ben
authors.initials: B
authors.lastname: Quansah
authors.forename: Natasha
authors.initials: N
authors.lastname: Patel
authors.forename: Steven
authors.initials: S
authors.lastname: Dakin
authors.forename: Shin'ya
authors.initials: S
authors.lastname: Nishida
mesh_terms: D000328:Adult; D004410:Dyslexia / Q000523:psychology*; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D006801:Humans; D008297:Male; D010469:Perceptual Distortion / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011594:Psychometrics; D011601:Psychophysics; D011930:Reaction Time; D012684:Sensory Thresholds / Q000502:physiology; D013998:Time Perception / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*