title: Mapping Common Aphasia Assessments to Underlying Cognitive Processes and Their Neural Substrates.
abstract: BACKGROUND
  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.
authors.affiliation: 1 Georgetown University Medical Center, Washington, DC, USA.|2 MedStar National Rehabilitation Hospital, Washington, DC, USA.
authors.forename: Elizabeth H
authors.initials: EH
authors.lastname: Lacey
authors.affiliation: 1 Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Skipper-Kallal
authors.affiliation: 1 Georgetown University Medical Center, Washington, DC, USA.|3 First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China.
authors.forename: Shihui
authors.initials: S
authors.lastname: Xing
authors.affiliation: 1 Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Mackenzie E
authors.initials: ME
authors.lastname: Fama
authors.affiliation: 1 Georgetown University Medical Center, Washington, DC, USA.|2 MedStar National Rehabilitation Hospital, Washington, DC, USA.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Turkeltaub
mesh_terms: D000328:Adult; D000368:Aged; D001037:Aphasia / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology*; D001931:Brain Mapping; D003071:Cognition / Q000502:physiology*; D056344:Executive Function / Q000502:physiology; D005163:Factor Analysis, Statistical; D005260:Female; D007839:Functional Laterality; D006801:Humans; D021621:Imaging, Three-Dimensional; D007858:Learning / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term; D008875:Middle Aged; D009483:Neuropsychological Tests; D012044:Regression Analysis; D020521:Stroke / Q000150:complications
keywords: MRI; aphasia; executive function; language; neuropsychological assessment