FMRI of Ventral and Dorsal Processing Streams in Basic Reading Processes: Insular Sensitivity to Phonology
- 660 Downloads
Most current models of the neurophysiology of basic reading processes agree on a system involving two cortical streams: a ventral stream (occipital-temporal) used when accessing familiar words encoded in lexical memory, and a dorsal stream (occipital-parietal-frontal) used when phonetically decoding words (i.e., mapping sublexical spelling onto sounds). The models diverge, however, on the issue of whether the insular cortex is involved. The present fMRI study required participants to read aloud exception words (e.g., ‘one’, which must be read via lexical memory) and pseudohomophones (e.g., ‘wun’, which must be read via sublexical spelling to sound translation) to examine the processing streams as well as the insular cortex, and their relationship to lexical and sublexical reading processes. The present study supports the notion of independent ventral-lexical and dorsal-sublexical streams, and further suggests the insular cortex to be sensitive to phonological processing (particularly sublexical spelling-sound translation). These latter findings illuminate the nature of insular activity during reading, which must be explored further in future studies, and accounted for in models of the neurophysiology of reading.
KeywordsfMRI Localization Visual pathways Ventral stream Dorsal stream Lexical Sublexical Exception words Pseudohomophones
Unable to display preview. Download preview PDF.
- Binder, J. and Price, C.J. Functional neuroimaging of language. In: R. Cabeza and A. Kingstone (Eds.), Handbook of Functional Neuroimaging of Cognition, 2001: 187–251. Cambridge, MA: MIT Press.Google Scholar
- Cox, R.W. AFNI: Software for analysis and visualization of functional magnetic resonance neuroimages. Comput. Biomed. Res., 1996, 29: 162–173. [AFNI 3-d anatomical brain available at: http://afni.nimh.nih.gov/old/afni/ astrip±orig.HEAD (and BRIK)].
- Demb, J., Poldrack, R.A. and Gabrieli, J.D.E. Functional neuroimaging of word processing in normal and dyslexic readers. In: R.M. Klein and P.A. McMullen (Eds.), Converging Methods for Understanding Reading and Dyslexia, 1999: 245–304. Cambridge, MA: MIT Press.Google Scholar
- Goldstein, E.B. Sensation and Perception (6th ed.), 2002. Pacific Grove, CA: Wadsworth-Thomson.Google Scholar
- Posner, M.I. and Raichle, M.E. Images of mind, 1994, New York: Scientific American Library.Google Scholar
- Talairach, J. and Tournoux, P. Co-planar stereotaxic atlas of the human brain, 1988. New York: Thieme Medical Publishers, Inc.Google Scholar
- Young, M.P. Open questions about the neural mechanisms of visual pattern recognition. In: M.S. Gazzaniga (Ed.), The Cognitive Neurosciences, 1995: 463–474. Cambridge, MA: MIT Press.Google Scholar