title: Representation of visual symbols in the visual word processing network.
abstract: BACKGROUND
  Previous studies have shown that word processing involves a predominantly left-sided occipitotemporal network. Words are a form of symbolic representation, in that they are arbitrary perceptual stimuli that represent other objects, actions or concepts. Lesions of parts of the visual word processing network can cause alexia, which can be associated with difficulty processing other types of symbols such as musical notation or road signs.
  
  
  OBJECTIVE
  We investigated whether components of the visual word processing network were also activated by other types of symbols.
  
  
  METHODS
  In 16 music-literate subjects, we defined the visual word network using fMRI and examined responses to four symbolic categories: visual words, musical notation, instructive symbols (e.g. traffic signs), and flags and logos. For each category we compared responses not only to scrambled stimuli, but also to similar stimuli that lacked symbolic meaning.
  
  
  RESULTS
  The left visual word form area and a homologous right fusiform region responded similarly to all four categories, but equally to both symbolic and non-symbolic equivalents. Greater response to symbolic than non-symbolic stimuli occurred only in the left inferior frontal and middle temporal gyri, but only for words, and in the case of the left inferior frontal gyri, also for musical notation. A whole-brain analysis comparing symbolic versus non-symbolic stimuli revealed a distributed network of inferior temporooccipital and parietal regions that differed for different symbols.
  
  
  CONCLUSIONS
  The fusiform gyri are involved in processing the form of many symbolic stimuli, but not specifically for stimuli with symbolic content. Selectivity for stimuli with symbolic content only emerges in the visual word network at the level of the middle temporal and inferior frontal gyri, but is specific for words and musical notation.
authors: Department of Medicine (Neurology), Department of Ophthalmology and Visual Sciences, University of British Columbia, Canada; Department of Medicine (Neurology), King Saud University, Riyadh, Saudi Arabia. Electronic address: tmuayqil@gmail.com.
authors: Taim
authors: T
authors: Muayqil
authors: Department of Medicine (Neurology), Department of Ophthalmology and Visual Sciences, University of British Columbia, Canada. Electronic address: jodie.davies@unitn.it.
authors: Jodie
authors: J
authors: Davies-Thompson
authors: Department of Medicine (Neurology), Department of Ophthalmology and Visual Sciences, University of British Columbia, Canada. Electronic address: jasonbarton@shaw.ca.
authors: Jason J S
authors: JJ
authors: Barton
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009146:Music; D009434:Neural Pathways / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011932:Reading; D055815:Young Adult
keywords: FMRI; Neuroimaging; Object recognition; Visual word form area