Neural substrates of verbal repetition deficits in primary progressive aphasia

Abstract

In this cross-sectional study, we examined the relationship between cortical thickness and performance on several verbal repetition tasks in a cohort of patients with primary progressive aphasia in order to test predictions generated by theoretical accounts of phonological working memory that predict phonological content buffers in left posterior inferior frontal sulcus and supramarginal gyrus. Cortical surfaces were reconstructed from magnetic resonance imaging scans from 42 participants diagnosed with primary progressive aphasia. Cortical thickness was measured in a set of anatomical regions spanning the entire cerebral cortex. Correlation analyses were performed between cortical thickness and average score across three phonological working memory related tasks: the Repetition subtest from the Western Aphasia Battery, a forward digit span task, and a backward digit span task. Significant correlations were found between average working memory score across tasks and cortical thickness in left supramarginal gyrus and left posterior inferior frontal sulcus, in support of prior theoretical accounts of phonological working memory. Exploratory whole-brain correlation analyses performed for each of the three behavioral tasks individually revealed a distinct set of positively-correlated regions for each task. Comparison of cortical thickness measures from different primary progressive aphasia subtypes to cortical thickness in age-matched controls further revealed unique patterns of atrophy in the different subtypes.

Network anatomy in logopenic variant of primary progressive aphasia

“…By employing brain–behavior correlation analyses to evaluate the relation between the structural integrity of each ICN identified in the healthy brain and these core symptoms of lvPPA, we were able to isolate two behaviorally relevant networks: one anchored in the left PFm, which was preferentially associated with auditory–verbal short‐term memory (sentence repetition) and one in the left PSL, which was implicated in lexical retrieval (confrontation naming). The two ICNs identified in this study as preferentially involved in sentence repetition and confrontation naming are consistent with findings from previous literature in post‐stroke aphasia, functional imaging in healthy controls, and PPA (Forkel et al, 2020 ; Fridriksson et al, 2010 ; Miller et al, 2021 ; Rogalsky et al, 2015 ). Specifically, language production skills have been linked to a large‐scale network involving frontal‐temporal–parietal regions (Gleichgerrcht et al, 2015 ; Indefrey & Levelt, 2004 ; Mesulam et al, 2014 ; Migliaccio et al, 2016 ; Milton et al, 2021 ) with the left angular gyrus (including PFm) being specifically associated with impaired confrontation naming (DeLeon et al, 2007 ) and the TPJ (including PSL) with repetition skills (Baldo et al, 2012 ; Buchsbaum & D'Esposito, 2009 ; Lukic et al, 2019 ; Majerus, 2013 ).…”

“…By employing brain-behavior correlation analyses to evaluate the relation between the structural integrity of each ICN identified in the healthy brain and these core symptoms of lvPPA, we were able to isolate two behaviorally relevant networks: one anchored in the left PFm, which was preferentially associated with auditory-verbal short-term memory (sentence repetition) and one in the left PSL, which was implicated in lexical retrieval (confrontation naming). The two ICNs identified in this study as preferentially involved in sentence repetition and confrontation naming are consistent with findings from previous literature in poststroke aphasia, functional imaging in healthy controls, and PPA(Forkel et al, 2020;Fridriksson et al, 2010;Miller et al, 2021; Rogalsky F I G U R E 4 Functional connectivity in selected healthy control-intrinsic connectivity networks (HC-ICNs) predicts longitudinal cortical change in logopenic variant of primary progressive aphasia (lvPPA). Scatterplots of the correlation between the shortest functional path length from the left PFm, perisylvian language (PSL), and right AICC in the HC group and the longitudinal change in cortical thickness in lvPPA.…”

The unique role of the frontal aslant tract in speech and language processing

“…Specifically, comprehension has been associated with temporal lobe regions and BA 46/47 ( Dronkers et al, 2004 , Turken and Dronkers, 2011 ), naming has been associated with the middle temporal gyrus ( Baldo et al, 2013 ), and repetition has been associated with the superior temporal gyrus/sulcus and temporo-parietal cortex ( Baldo et al, 2012 , Miller et al, 2021 ). Thus, as predicted, damage to the FAT was not associated with decreased performance on repetition, naming, and comprehension tasks.…”

Neuroanatomical correlates of screening for aphasia in NeuroDegeneration (SAND) battery in non-fluent/agrammatic variant of primary progressive aphasia

“…From this point of view, this is the first study that assessed structural neuroimaging correlates of naming specifically in avPPA, potentially demonstrating a left-sided dominance (in particular for temporal regions) for naming functioning. On the other hand, sentence repetition (total score) has been linked to the left temporoparietal junction (Amici et al, 2007 ; Lukic et al, 2019 ; Miller et al, 2021 ) with also the involvement of the middle and anterior temporal gyri (Fedorenko et al, 2010 ; Friederici and Gierhan, 2013 ). Furthermore, the semantic fluency test demonstrated a slight correlation with the left temporal network, not surviving multiple comparisons.…”