Subcortical structures in aphasia. An analysis based on (F-18)-fluorodeoxyglucose, positron emission tomography, and computed tomography
E. J. Metter, W. H. Riege, W. R. Hanson, C. A. Jackson, D. Kempler and D. van Lancker
National Institute of Aging, Gerontology Research Center, Baltimore, MD 21224.
Subcortical structural damage that includes the anterior and posterior
internal capsule, caudate, thalamus, lenticular nuclei, and insula has been
shown to cause aphasias. A critical question that has not been resolved is
whether the role of these structures on behavior is a direct one or whether
it is indirect through the cortex. We have used pathway analysis to
evaluate computed tomography, glucose metabolic, and language data from 47
aphasic patients to answer this question. For fluency (from the Western
Aphasia Battery), subcortical structural damage had direct and indirect
(through frontal lobe) effects on the behavior. For a comprehension task
(sequential commands), subcortical damage had no direct effect and only a
slight indirect effect through the temporal lobe. Thus, both direct and
indirect effects of subcortical damage can be demonstrated for specific
behavioral measures.
