Neural Representations of Visual Words and Objects: A Functional MRI Study on the Modularity of Reading and Object Processing
- 285 Downloads
There have been several studies supporting the notion of a ventral-dorsal distinction in the primate cortex for visual object processing, whereby the ventral stream specializes in object identification, and the dorsal stream is engaged during object localization and interaction. There is also a growing body of evidence supporting a ventral stream that specializes in lexical (i.e., whole-word) reading, and a dorsal stream that is engaged during sub-lexical reading (i.e., phonetic decoding). Here, we consider the extent to which word-reading processes are located in regions either intersecting with, or unique from, regions that sub-serve object processing along these streams. Object identification was contrasted with lexical-based reading, and object interaction processing (i.e., deciding how to interact with an object) was contrasted with sub-lexical reading. Our results suggest that object identification and lexical-based reading are largely ventral and modular, showing mainly unique regions of activation (parahippocampal and occipital-temporal gyri function associated with object identification, and lingual, lateral occipital, and posterior inferior temporal gyri function associated with lexical-based reading) and very little shared activation (posterior inferior frontal gyrus). Object interaction processing and phonetic decoding are largely dorsal, and show both modular regions of activation (more lateralized to the dorsal-frontal right hemisphere for pseudohomophone naming, and more to the dorsal-frontal left hemisphere for the object interaction task) as well as significant shared regions of processing (precentral gyri, left inferior frontal cortex, left postcentral gyrus, left lateral occipital cortex, and superior posterior temporal gyri). Given that the perceptual experimental conditions show primarily modular and very little shared processing, whereas the analytical conditions show both substantial modular and shared processing, we discuss a reconsideration of “modularity of mind” which involves a continuum between strictly modular processing and varying degrees of shared processing, and which also depends on the nature of the tasks compared (i.e., perceptual versus analytical).
KeywordsNaming Task Dorsal Stream Ventral Stream Object Interaction Hemodynamic Response Function
Unable to display preview. Download preview PDF.
This research was supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada in the form of grants to R.B. and G.E.S.
- 1.Binder J, Price CJ. Functional neuroimaging of language. In: Cabeza R, Kingstone A, editors. Handbook of functional neuroimaging of cognition. Cambridge: MIT Press; 2001. p. 187–241.Google Scholar
- 6.Cox RW. AFNI: software for analysis and visualization of functional magnetic resonance neuroimages. Comp Biomed Res 1996;29:162–173. [AFNI 3-d anatomical brain available at: http:// www.afni.nimh.nih.gov/old/afni/astrip±orig.HEAD (and BRIK)].
- 7.D’esposito M. Functional neuroimaging of working memory. In: Cabeza R, Kingstone A editors. Handbook of functional neuroimaging of cognition. Cambridge: MIT Press; 2001. p. 293–327.Google Scholar
- 8.Fodor J. The modularity of mind. Cambridge: MIT Press; 1983.Google Scholar
- 9.Fodor J. The mind doesn’t work that way. Cambridge: MIT Press; 2000.Google Scholar
- 11.Goldstein EB. Sensation and perception. 6th ed. Pacific Grove: Wadsworth-Thomson; 2002.Google Scholar
- 12.Goodale MA, Milner AD. Sight unseen: an exploration of conscious and unconscious vision. Oxford: Oxford University Press; 2005.Google Scholar
- 14.Ishai A, Ungerleider LG, Martin A, Schouten JL, Haxby JV. Distributed representation of objects in the human ventral visual pathway. Neurobiology 1999;96:9379–84.Google Scholar
- 15.Kanwisher N, Downing P, Epstein R, Kourtzi Z. Functional neuroimaging of visual recognition. In: Cabeza R, Kingstone A editors. Handbook of functional neuroimaging of cognition. Cambridge: MIT Press; 2001. p. 109–51.Google Scholar
- 16.Kirk EC, Kay RF. The evolution of high visual acuity in the anthropoidea. In: Ross CF, Kay RF editors. Anthropoid origins: new visions. New York: Kluwer/Plenum Publishing; 2004, 539–602.Google Scholar
- 18.Martin A. Functional neuroimaging of semantic memory. In: Cabeza R, Kingstone A editors. Handbook of functional neuroimaging of cognition. Cambridge MA: MIT Press; 2001, p.␣153–86.Google Scholar
- 21.Milner AD, Goodale MA. The visual brain in action. Oxford: Oxford University Press; 1995.Google Scholar
- 23.Posner MI, Raichle ME. Images of mind. New York: Scientific American Library; 1994.Google Scholar
- 27.Talairach J, Tournoux P. Co-planar stereotaxic atlas of the human brain. New York: Thieme Medical Publishers, Inc; 1988.Google Scholar
- 30.Ungerleider LG, Mishkin M. Two cortical visual systems. In: Ingle DJ, Goodale MA, Mansfield RJW editors. Analysis of visual behaviour. Cambridge: MIT Press; 1982. p. 549–86.Google Scholar