title: Sequential then interactive processing of letters and words in the left fusiform gyrus.
abstract: Despite decades of cognitive, neuropsychological and neuroimaging studies, it is unclear if letters are identified before word-form encoding during reading, or if letters and their combinations are encoded simultaneously and interactively. Here using functional magnetic resonance imaging, we show that a 'letter-form' area (responding more to consonant strings than false fonts) can be distinguished from an immediately anterior 'visual word-form area' in ventral occipito-temporal cortex (responding more to words than consonant strings). Letter-selective magnetoencephalographic responses begin in the letter-form area ∼60 ms earlier than word-selective responses in the word-form area. Local field potentials confirm the latency and location of letter-selective responses. This area shows increased high-gamma power for ∼400 ms, and strong phase-locking with more anterior areas supporting lexico-semantic processing. These findings suggest that during reading, visual stimuli are first encoded as letters before their combinations are encoded as words. Activity then rapidly spreads anteriorly, and the entire network is engaged in sustained integrative processing.
authors.affiliation: Department of Neurology, Comprehensive Epilepsy Center, New York University, New York, NY 10016, USA. thomas.thesen@med.nyu.edu
authors.forename: Thomas
authors.initials: T
authors.lastname: Thesen
authors.forename: Carrie R
authors.initials: CR
authors.lastname: McDonald
authors.forename: Chad
authors.initials: C
authors.lastname: Carlson
authors.forename: Werner
authors.initials: W
authors.lastname: Doyle
authors.forename: Syd
authors.initials: S
authors.lastname: Cash
authors.forename: Jason
authors.initials: J
authors.lastname: Sherfey
authors.forename: Olga
authors.initials: O
authors.lastname: Felsovalyi
authors.forename: Holly
authors.initials: H
authors.lastname: Girard
authors.forename: William
authors.initials: W
authors.lastname: Barr
authors.forename: Orrin
authors.initials: O
authors.lastname: Devinsky
authors.forename: Ruben
authors.initials: R
authors.lastname: Kuzniecky
authors.forename: Eric
authors.initials: E
authors.lastname: Halgren
mesh_terms: D004569:Electroencephalography; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D009778:Occipital Lobe / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011932:Reading; D012660:Semantics; D013702:Temporal Lobe / Q000502:physiology*