ABSTRACT
BACKGROUND: Patterns of language impairment have long been used clinically to localize brain damage in stroke patients. The same approach might be useful in the differential diagnosis of progressive aphasia owing to neurodegenerative disease. OBJECTIVE: To investigate whether scores on 4 widely used language tasks correlate with regional gray matter loss in 51 patients with progressive language impairment owing to neurodegenerative disease. METHOD: Scores in the Boston Naming Test and in the "repetition" "sequential commands" and the "language fluency," subtests of the Western Aphasia Battery were correlated with voxel-wise gray matter volumes using voxel-based morphometry. RESULTS: Significant positive correlations were found between each language task and regional brain volumes: (1) naming and the bilateral temporal lobes; (2) sentence repetition and the left posterior portion of the superior temporal gyrus; (3) sentence comprehension and the left dorsal middle and inferior frontal gyri; and (4) fluency of language production and the left ventral middle and inferior frontal gyri. DISCUSSION: Performance on specific language tasks corresponds to regional anatomic damage in aphasia owing to neurodegenerative disorders. These language tests might be useful in the differential diagnosis of primary progressive aphasia variants that have been previously associated with damage to corresponding anatomic regions.
Subject(s)
Aphasia, Primary Progressive/diagnosis , Image Processing, Computer-Assisted , Imaging, Three-Dimensional , Magnetic Resonance Imaging , Neurodegenerative Diseases/diagnosis , Neuropsychological Tests/statistics & numerical data , Aged , Anomia/diagnosis , Anomia/psychology , Aphasia, Primary Progressive/psychology , Atrophy , Brain Mapping , Comprehension/physiology , Diagnosis, Differential , Dominance, Cerebral/physiology , Female , Frontal Lobe/pathology , Hippocampus/pathology , Humans , Male , Memory, Short-Term/physiology , Middle Aged , Neurodegenerative Diseases/psychology , Parahippocampal Gyrus/pathology , Psychometrics , Statistics as Topic , Temporal Lobe/pathologyABSTRACT
This study investigates whether sentence comprehension and nonsyntactic verbal working memory (vWM) are sustained by the same or by different neural systems. Scores in a sentence-picture matching task and in digits backward (DB) were correlated with magnetic resonance imaging voxelwise gray matter volumes using voxel-based morphometry in 58 patients with neurodegenerative diseases. Results showed that overall sentence comprehension scores, regardless of grammatical structure, correlated with gray matter volumes in the left temporoparietal region, whereas DB scores correlated with dorsolateral prefrontal and inferior parietal volumes. Comprehension of multiclausal relative sentences (type 3) significantly correlated with voxels in the dorsal portion of the left inferior and middle frontal gyri. When DB and multiclausal relative sentences were directly compared, they showed overlapping neural substrates in the dorsolateral left frontal region, supporting a single source of vWM for syntactic and nonsyntactic tasks. Within this large area of common involvement, a small portion of pars triangularis showed an independent effect of multiclausal sentences, whereas a region in the middle frontal gyrus showed greater correlation with DB. This study reconciles two opposing views, which hold that sentence comprehension and vWM rely on either the same or different anatomical resources.
