How low can you go: Spatial frequency sensitivity in a patient with pure alexia

Randi Starrfelt, Simon Nielsen, Thomas Habekost, Tobias Andersen

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Abstract

Pure alexia is a selective deficit in reading, following lesions to the posterior left hemisphere. Writing and other language functions remain intact in these patients. Whether pure alexia is caused by a primary problem in visual perception is highly debated. A recent hypothesis suggests that a low level deficit – reduced sensitivity to particular spatial frequencies – is the underlying cause. We tested this hypothesis in a pure alexic patient (LK), using a sensitive psychophysical paradigm to examine her performance with simple patterns of different spatial frequency. We find that both in a detection and a classification task, LK’s contrast sensitivity is comparable to normal controls for all spatial frequencies. Thus, reduced spatial frequency sensitivity does not constitute a general explanation for pure alexia, suggesting that the core deficit in this disorder is at a higher level in the visual processing stream.
Original languageEnglish
JournalBrain and Language
Volume126
Issue number2
Pages (from-to)188-192
ISSN0093-934X
DOIs
Publication statusPublished - 2013

Bibliographical note

This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike License, which permits noncommercial use, distribution, and reproduction in any medium, provided the original author and source are credited.

Keywords

  • Pure alexia
  • Word length effect
  • Word reading
  • Case study
  • LBL-reading
  • Spatial frequency sensitivity
  • Contrast sensitivity

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