Voxel-lesion symptom mapping of coarse coding and suppression deficits in right hemisphere damaged patients

Several accounts of narrative comprehension deficits in adults with right hemisphere damage (RHD) focus on the basic comprehension processes of coarse semantic coding (CC) and suppression (SUP)1,2. CC activates wide-ranging aspects of word meaning, independent of the surrounding context. In RHD, CC deficits impair processing of more remote meanings/features of lexical-semantic representations (e.g., “rotten” as a feature of “apple”)3. The normal SUP process reduces mental activation of concepts that become contextually incompatible. SUP impairment in RHD is indexed by prolonged processing interference from contextually-inappropriate interpretations (e.g., the “ink” meaning of “pen,” in “He built a pen”)4,5. Adults with RHD may have deficits in CC, SUP, both, or neither6. Voxel-based lesion symptom mapping was used to identify right hemisphere (RH) anatomical correlates of CC and SUP deficits. Lesion-deficit correspondence data should help predict which RHD patients have which deficits and may be candidates for a deficit-focused treatment approach that simultaneously improves narrative comprehension7-9. The Bilateral Activation, Integration, and Selection (BAIS) framework of language processing10 suggests some basic hypotheses1. CC, related to the activation component, is hypothesized to involve posterior MTG and STG10,11. SUP, related to the attentionally-driven selection component, modulates lexical-level activation and message-level semantic integration to narrow representations to those most relevant to a comprehender’s goal. Selection is strongly associated with left IFGe.g,12 but RH IFG also is crucial for semantic filtering and selection13,14, especially for information more strongly active in the RH15. Basal ganglia circuits are likely involved, as well13,16