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

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Dokumenter

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

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.
OriginalsprogEngelsk
TidsskriftBrain and Language
Vol/bind126
Udgave nummer2
Sider (fra-til)188-192
Antal sider5
ISSN0093-934X
DOI
StatusUdgivet - 2013

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