How low can you go?: Spatial frequency sensitivity in pure alexia

Randi Starrfelt; Simon Nielsen; Thomas Habekost; Tobias S. Andersen

doi:10.1016/j.bandl.2013.05.006

How low can you go? Spatial frequency sensitivity in pure alexia

Randi Starrfelt, Simon Nielsen, Thomas Habekost, Tobias S. Andersen

14 Citations (Scopus)

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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 language	English
Journal	Brain and Language
Volume	126
Issue number	2
Pages (from-to)	188-192
Number of pages	5
ISSN	0093-934X
DOIs	https://doi.org/10.1016/j.bandl.2013.05.006
Publication status	Published - Aug 2013

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10.1016/j.bandl.2013.05.006

Starrfelt et al Spatial frequency B L 2013Accepted author manuscript, 757 KB

Cite this

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title = "How low can you go?: Spatial frequency sensitivity in pure alexia",

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{\textquoteright}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.",

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AU - Nielsen, Simon

AU - Habekost, Thomas

AU - Andersen, Tobias S.

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AB - 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.

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