title: Uncovering phonological and orthographic selectivity across the reading network using fMRI-RA.
abstract: Reading has been shown to rely on a dorsal brain circuit involving the temporoparietal cortex (TPC) for grapheme-to-phoneme conversion of novel words (Pugh et al., 2001), and a ventral stream involving left occipitotemporal cortex (OTC) (in particular in the so-called "visual word form area", VWFA) for visual identification of familiar words. In addition, portions of the inferior frontal cortex (IFC) have been posited to be an output of the dorsal reading pathway involved in phonology. While this dorsal versus ventral dichotomy for phonological and orthographic processing of words is widely accepted, it is not known if these brain areas are actually strictly sensitive to orthographic or phonological information. Using an fMRI rapid adaptation technique we probed the selectivity of the TPC, OTC, and IFC to orthographic and phonological features during single word reading. We found in two independent experiments using different task conditions in adult normal readers, that the TPC is exclusively sensitive to phonology and the VWFA in the OTC is exclusively sensitive to orthography. The dorsal IFC (BA 44), however, showed orthographic but not phonological selectivity. These results support the theory that reading involves a specific phonological-based temporoparietal region and a specific orthographic-based ventral occipitotemporal region. The dorsal IFC, however, was not sensitive to phonological processing, suggesting a more complex role for this region.
authors.affiliation: Department of Neuroscience, Georgetown University Medical Center, 3800 Reservoir Rd. NW, Washington, District of Columbia 20007, USA; Departments of Psychology and Speech, Language and Hearing Sciences, San Diego State University, 6505 Alvarado Rd., Suite 203, San Diego, CA 92120, USA. Electronic address: lglezer@mail.sdsu.edu.
authors.forename: Laurie S
authors.initials: LS
authors.lastname: Glezer
authors.affiliation: Department of Pediatrics, Georgetown University Medical Center, 3970 Reservoir Rd. NW, Washington, District of Columbia 20007, USA.
authors.forename: Guinevere
authors.initials: G
authors.lastname: Eden
authors.affiliation: Department of Neuroscience, Georgetown University Medical Center, 3800 Reservoir Rd. NW, Washington, District of Columbia 20007, USA.
authors.forename: Xiong
authors.initials: X
authors.lastname: Jiang
authors.affiliation: Department of Pediatrics, Georgetown University Medical Center, 3970 Reservoir Rd. NW, Washington, District of Columbia 20007, USA.
authors.forename: Megan
authors.initials: M
authors.lastname: Luetje
authors.affiliation: Department of Pediatrics, Georgetown University Medical Center, 3970 Reservoir Rd. NW, Washington, District of Columbia 20007, USA.
authors.forename: Eileen
authors.initials: E
authors.lastname: Napoliello
authors.affiliation: Department of Neuroscience, Georgetown University Medical Center, 3800 Reservoir Rd. NW, Washington, District of Columbia 20007, USA; Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 N. Charles St. Baltimore, MD 21218, USA.
authors.forename: Judy
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Neuroscience, Georgetown University Medical Center, 3800 Reservoir Rd. NW, Washington, District of Columbia 20007, USA.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Riesenhuber
mesh_terms: D001931:Brain Mapping / Q000379:methods; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009415:Nerve Net / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010700:Phonetics; D011932:Reading; D013702:Temporal Lobe / Q000502:physiology*; D014706:Verbal Learning / Q000502:physiology*
keywords: Homophones; Neural specificity; Orthography; Phonology; Reading; VWFA