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Experience-dependent hemispheric specialization of letters and numbers is revealed in early visual processing.

Publication ,  Journal Article
Park, J; Chiang, C; Brannon, EM; Woldorff, MG
Published in: J Cogn Neurosci
October 2014

Recent fMRI research has demonstrated that letters and numbers are preferentially processed in distinct regions and hemispheres in the visual cortex. In particular, the left visual cortex preferentially processes letters compared with numbers, whereas the right visual cortex preferentially processes numbers compared with letters. Because letters and numbers are cultural inventions and are otherwise physically arbitrary, such a double dissociation is strong evidence for experiential effects on neural architecture. Here, we use the high temporal resolution of ERPs to investigate the temporal dynamics of the neural dissociation between letters and numbers. We show that the divergence between ERP traces to letters and numbers emerges very early in processing. Letters evoked greater N1 waves (latencies 140-170 msec) than did numbers over left occipital channels, whereas numbers evoked greater N1s than letters over the right, suggesting letters and numbers are preferentially processed in opposite hemispheres early in visual encoding. Moreover, strings of letters, but not single letters, elicited greater P2 ERP waves (starting around 250 msec) than numbers did over the left hemisphere, suggesting that the visual cortex is tuned to selectively process combinations of letters, but not numbers, further along in the visual processing stream. Additionally, the processing of both of these culturally defined stimulus types differentiated from similar but unfamiliar visual stimulus forms (false fonts) even earlier in the processing stream (the P1 at 100 msec). These findings imply major cortical specialization processes within the visual system driven by experience with reading and mathematics.

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Published In

J Cogn Neurosci

DOI

EISSN

1530-8898

Publication Date

October 2014

Volume

26

Issue

10

Start / End Page

2239 / 2249

Location

United States

Related Subject Headings

  • Young Adult
  • Visual Perception
  • Visual Cortex
  • Semantics
  • Photic Stimulation
  • Mathematics
  • Male
  • Humans
  • Female
  • Experimental Psychology
 

Citation

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Park, J., Chiang, C., Brannon, E. M., & Woldorff, M. G. (2014). Experience-dependent hemispheric specialization of letters and numbers is revealed in early visual processing. J Cogn Neurosci, 26(10), 2239–2249. https://doi.org/10.1162/jocn_a_00621
Park, Joonkoo, Crystal Chiang, Elizabeth M. Brannon, and Marty G. Woldorff. “Experience-dependent hemispheric specialization of letters and numbers is revealed in early visual processing.J Cogn Neurosci 26, no. 10 (October 2014): 2239–49. https://doi.org/10.1162/jocn_a_00621.
Park J, Chiang C, Brannon EM, Woldorff MG. Experience-dependent hemispheric specialization of letters and numbers is revealed in early visual processing. J Cogn Neurosci. 2014 Oct;26(10):2239–49.
Park, Joonkoo, et al. “Experience-dependent hemispheric specialization of letters and numbers is revealed in early visual processing.J Cogn Neurosci, vol. 26, no. 10, Oct. 2014, pp. 2239–49. Pubmed, doi:10.1162/jocn_a_00621.
Park J, Chiang C, Brannon EM, Woldorff MG. Experience-dependent hemispheric specialization of letters and numbers is revealed in early visual processing. J Cogn Neurosci. 2014 Oct;26(10):2239–2249.
Journal cover image

Published In

J Cogn Neurosci

DOI

EISSN

1530-8898

Publication Date

October 2014

Volume

26

Issue

10

Start / End Page

2239 / 2249

Location

United States

Related Subject Headings

  • Young Adult
  • Visual Perception
  • Visual Cortex
  • Semantics
  • Photic Stimulation
  • Mathematics
  • Male
  • Humans
  • Female
  • Experimental Psychology