Cortical and structural-connectivity damage correlated with impaired syntactic processing in aphasia

Human Brain Mapping. 2019. Vol. 40. No. 7. P. 2153–2173.

Den Ouden D., Malyutina S., Basilakos A., Bonilha L., Gleichgerrcht E., Yourganov G., Hillis A., Hickok G., Rorden C., Fridriksson J.

Agrammatism in aphasia is not a homogeneous syndrome, but a characterization of a nonuniform set
of language behaviors in which grammatical markers and complex syntactic structures are omitted,
simplified, or misinterpreted. In a sample of 71 left-hemisphere stroke survivors, syntactic processing
was quantifiedwith theNorthwestern Assessment of Verbs and Sentences (NAVS). Classification analyses
were used to assess the relation between NAVS performance and morphosyntactically reduced
speech in picture descriptions. Voxel-based and connectivity-based lesion-symptom mapping were
applied to investigate neural correlates of impaired syntactic processing. Despite a nonrandom correspondence
between NAVS performance and morphosyntactic production deficits, there was variation
in individual patterns of syntactic processing. Morphosyntactically reduced production was predicted
by lesions to left-hemisphere inferior frontal cortex. Impaired verb argument structure production was
predicted by damage to left-hemisphere posterior superior temporal and angular gyrus, as well as to a
ventral pathway between temporal and frontal cortex. Damage to this pathway was also predictive of
impaired sentence comprehension and production, particularly of noncanonical sentences. Although
agrammatic speech production is primarily predicted by lesions to inferior frontal cortex, other aspects
of syntactic processing rely rather on regional integrity in temporoparietal cortex and the ventral
stream.

Keywords: синтаксис, syntax, Agrammatism, афазия, аграмматизм, magnetic resonance imaging, магнитно-резонансная томография, aphasia, повоксельное картирование симптом-поражения, voxel-based lesion-symptom mapping