Brain areas that mediate sentence comprehension in primary progressive aphasia: Evidence from perfusion imaging

EasyChair Preprint 6483

Abstract

Beyond core linguistic deficits, individuals with aphasia exhibit concomitant deficits in executive functions, in particular working memory (WM). In this study, we asked whether performance on a WM task (Digit Span backward; DSB) predicts performance on sentence comprehension (SOAP) and which brain areas mediate such effects, particularly the left middle frontal gyrus (MFG), an important area for WM or the left inferior frontal gyrus (IFG), a typical language area.

Thirty-six participants with PPA underwent comprehensive baseline cognitive-linguistic evaluations followed by an MRI, specifically a pCASL sequence. Cerebral blood flow maps were generated from the pCASL MRI images using JHU’s cloud-based ASL analysis software. Simple linear regression showed predictive values for behavioral measures and perfusion, and multiple linear regression revealed mediation effects.

Performance on DSB significantly predicted performance on SOAP and was significantly associated with perfusion of the left MFG and left IFG opercularis (IFGoperc). Importantly, DSB was not associated with perfusion of the IFG triangularis (IFGtri). When DSB and the left MFG were used in a multiple linear regression for SOAP, DSB had less predictive power of SOAP scores than the simple linear regression of DSB on SOAP, indicating a partial mediation effect of the left MFG. Similarly, when DSB and the left IFGoperc were used in a multiple linear regression for SOAP, DSB again had less predictive power of SOAP scores than its corresponding simple linear regression, indicating another partial mediation effect of the left IFGoperc.

The present study indicates that the left MFG and left IFGoperc partially mediate WM associations with sentence comprehension as previously shown in the literature. These findings highlight that performance on a basic WM test may predict sentence comprehension, mostly to the extent that MFG and IFGoperc are involved.

Keyphrases: Perfusion Imaging, mediation analysis, primary progressive aphasia, sentence comprehension, working memory

@booklet{EasyChair:6483,
  author    = {Olivia Herrmann and Alexandros Afthinos and Charalambos Themistocleous and Hongli Fan and Hanzhang Lu and Kyrana Tsapkini},
  title     = {Brain areas that mediate sentence comprehension in primary progressive aphasia: Evidence from perfusion imaging},
  howpublished = {EasyChair Preprint 6483},
  year      = {EasyChair, 2021}}