Article

Understanding the relationships between clinical tests, the processes they measure, and the brain networks underlying them, is critical in order for
clinicians to move beyond aphasia syndrome classification toward specification of
individual language process impairments. OBJECTIVE:
To understand the cognitive,
language, and neuroanatomical factors underlying scores of commonly used aphasia
tests. METHODS: Twenty-five behavioral tests were administered to a group of 38
chronic left hemisphere stroke survivors and a high-resolution magnetic resonance
image was obtained. Test scores were entered into a principal components analysis
to extract the latent variables (factors) measured by the tests. Multivariate
lesion-symptom mapping was used to localize lesions associated with the factor
scores. RESULTS: The principal components analysis yielded
4 dissociable factors,
which we labeled Word Finding/Fluency, Comprehension, Phonology/Working Memory
Capacity, and Executive Function. While many tests loaded onto the factors in
predictable ways, some relied heavily on factors not commonly associated with the
tests. Lesion symptom mapping demonstrated discrete brain structures associated
with each factor, including frontal, temporal, and parietal areas extending
beyond the classical language network. Specific functions mapped onto brain
anatomy largely in correspondence with modern neural models of language
processing. CONCLUSIONS: An extensive clinical aphasia assessment identifies 4
independent language functions, relying on discrete parts of the left middle
cerebral artery territory.
A better understanding of the processes underlying
cognitive tests and the link between lesion and behavior may lead to improved
aphasia diagnosis, and may yield treatments better targeted to an individual's
specific pattern of deficits and preserved abilities.

Langue : ANGLAIS