Uncovering Semantic Cognition Beyond Traditional Language batteries: Behavioural and Neural bases of the Semantic Knowledge Test

Semantic cognition allows us to represent, process and manipulate verbal and nonverbal knowledge about the surrounding environment. Semantic cognition plays a critical role in language, communication and many nonverbal behaviours and can be disrupted by several neurological diseases, including stroke and dementias. Therefore for clinical practice, it is essential to evaluate semantic cognition and to do so using culturally-appropriate assessments (given that some facets of semantic knowledge and associations are culturally-specific). Here, we developed and standardized a new verbal and nonverbal semantic assessment, called semantic knowledge test (SKT), for Korean-speaking populations. The SKT was developed and standardized on a large and demographically diverse sample of 325 healthy adults, confirming its high reliability and validity. To explore its clinical utility and added value, we collected data from 101 post-stroke patients alongside the Western Aphasia Battery (WAB). We run a principal component analysis (PCA) using SKT and WAB scores and Voxel-based lesion-symptom mapping (VLSM) using the factor loadings that yielded from the PCA. The principal component analysis (PCA) of behavioural test scores produced two distinctive factors, one with the WAB scores and the other with the SKT scores. VLSM revealed that the neuroanatomical correlates of the WAB factor covered the peri-Sylvian areas, while that of SKT was in the left superior anterior temporal lobe (ATL) and posterior middle temporal gyrus (pMTG). These findings underscore the utility of the SKT in uncovering both behavioural and neuroanatomical facets of semantic cognition that are not captured by the traditional language batteries such as the WAB and emphasize the importance of independent assessment of semantic deficits in clinical populations.