Fronto-Central Connectivity Discriminates Successful from Unsuccessful Phoneme Perception in Wernicke’s Aphasia

EasyChair Preprint 6642

Abstract

Background: Impaired phonological discrimination is a core symptom of Wernicke’s-type aphasia (WA). However, accurate discrimination can be observed when phonological changes are sufficiently acoustically distinct. Perception success may not be reflected magnitude of neural activity. This study tested the hypothesis that perception success is reflected in inter-regional connectivity within the speech perception network, observable in scalp-level connectivity measures.

Method: Seven WA and 7 neurotypical participants undertook an EEG multiple deviant MMN paradigm using CVC nonword stimuli. Deviant stimuli were perceptible or non-perceptible changes from the standard. Deviant stimuli were additionally presented in a standard “deviant alone” condition. Following pre-processing, imaginary coherence (IC) between all sensor pairs was calculated in the theta, alpha, beta and gamma bands pre, post and during the MMN signal. IC MMN change was calculated as the difference in IC during the MMN window in comparison to the deviant-alone stimuli and the pre and post time windows. The IC MMN change between the peak ERP MMN electrodes (FCz, Cz) and 9 sensor sub-sets was averaged and subjected to inferential statistics.  

Results: 2x2x3x3 ANOVA (group x perceptibility x anterior-posterior sets x left-right sets) found a main effect of perceptibility for IC MMN change in the theta band (F_(1,1)=7.7, p=0.02). Follow-up Wilcoxon tests found a significant IC perceptibility difference between central and right anterior sensors for the WA group (Z=-2.2, p=0.03).  

Conclusions: Theta connectivity distinguished phoneme perception success, irrespective of aphasia status or stimulus type. Theta oscillations may support integration of phonological information throughout the residual speech perception and attention networks.

Keyphrases: EEG, Wernicke's aphasia, auditory comprehension, functional connectivity, speech perception

@booklet{EasyChair:6642,
  author    = {Tina M. D Mello and Holly Robson},
  title     = {Fronto-Central Connectivity Discriminates Successful from Unsuccessful Phoneme Perception in Wernicke’s Aphasia},
  howpublished = {EasyChair Preprint 6642},
  year      = {EasyChair, 2021}}