Too Little, Too Late: Reduced Visual Span and Speed Characterize Pure Alexia

Overview

Journal Cereb Cortex

Publisher Oxford University Press

Specialty Neurology

Date 2009 Apr 16

PMID 19366870

Citations 33

Authors

Randi Starrfelt

Thomas Habekost

Alexander P Leff

Affiliations

Soon will be listed here.

Abstract

Whether normal word reading includes a stage of visual processing selectively dedicated to word or letter recognition is highly debated. Characterizing pure alexia, a seemingly selective disorder of reading, has been central to this debate. Two main theories claim either that 1) Pure alexia is caused by damage to a reading specific brain region in the left fusiform gyrus or 2) Pure alexia results from a general visual impairment that may particularly affect simultaneous processing of multiple items. We tested these competing theories in 4 patients with pure alexia using sensitive psychophysical measures and mathematical modeling. Recognition of single letters and digits in the central visual field was impaired in all patients. Visual apprehension span was also reduced for both letters and digits in all patients. The only cortical region lesioned across all 4 patients was the left fusiform gyrus, indicating that this region subserves a function broader than letter or word identification. We suggest that a seemingly pure disorder of reading can arise due to a general reduction of visual speed and span, and explain why this has a disproportionate impact on word reading while recognition of other visual stimuli are less obviously affected.

Citing Articles

Neuropsychological Diagnosis and Assessment of Alexia: A Mixed-Methods Study.

Alduais A, Alarifi H, Alfadda H Brain Sci. 2024; 14(7).

PMID: 39061376 PMC: 11274783. DOI: 10.3390/brainsci14070636.

Systematic evaluation of high-level visual deficits and lesions in posterior cerebral artery stroke.

Robotham R, Rice G, Leff A, Lambon Ralph M, Starrfelt R Brain Commun. 2023; 5(2):fcad050.

PMID: 36938522 PMC: 10018645. DOI: 10.1093/braincomms/fcad050.

Is Developmental Dyslexia Due to a Visual and Not a Phonological Impairment?.

Werth R Brain Sci. 2021; 11(10).

PMID: 34679378 PMC: 8534212. DOI: 10.3390/brainsci11101313.

The resilience of the developing reading system: multi-modal evidence of incident and recovery after a pediatric stroke.

Borghesani V, Wang C, Miller C, Mandelli M, Shapiro K, Miller Z Neurocase. 2021; 27(4):338-348.

PMID: 34503393 PMC: 8814732. DOI: 10.1080/13554794.2021.1957119.

Category-selective deficits are the exception and not the rule: Evidence from a case-series of 64 patients with ventral occipito-temporal cortex damage.

Rice G, Kerry S, Robotham R, Leff A, Lambon Ralph M, Starrfelt R Cortex. 2021; 138:266-281.

PMID: 33770511 PMC: 8064027. DOI: 10.1016/j.cortex.2021.01.021.

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