Page 132 - MEGIN Book Of Abstracts - 2023

speech edges in dyslexia. In the present study, we used entrainment to speech was found to be atypical in
MEG to record brain activity from normal and dyslexic dyslexia, a reading impairment associated with neural
readers while they listened to speech. We computed speech processing deficits. We hypothesized that the
phase locking values (PLVs) to evaluate phase entrain- brain responses of dyslexic vs. normal readers to real-
ment between neural oscillations and the speech life speech would be different, and thus the strength
envelope time-locked to edge onsets. In both groups, of inter-subject correlation (ISC) would differ from that
we observed that edge onsets induced phase resets of typical readers and be reflected in reading-related
in the auditory oscillations tracking speech, thereby measures. We recorded magnetoencephalograms
enhancing their entrainment to speech. Importantly, (MEG) of 23 dyslexic and 21 typically-reading adults
dyslexic readers showed weaker PLVs compared to during listening to ~10 min of natural Finnish speech
normal readers in left auditory regions from ~.15 sec to consisting of excerpts from radio news, a podcast, a
~.65 sec after edge onset. Our results indicate that the self-recorded audiobook chapter and small talk. The
neural mechanism that adapts cortical entrainment to amplitude envelopes of band-pass-filtered MEG source
the speech envelope is impaired in dyslexia. These find- signals were correlated between subjects in a cortical-
ings here are consistent with the temporal sampling ly-constrained source space in six frequency bands. The
theory of developmental dyslexia. resulting ISCs of dyslexic and typical readers were com-
pared with a permutation-based t-test. Neuropsycho-
Keywords: Dyslexia, Magnetoencephalography, Neural logical measures of phonological processing, technical
oscillations, Phonological deficit, Speech reading, and working memory were correlated with
the ISCs utilizing the Mantel test. During listening to
Cortex; a journal devoted to the study of the nervous speech, ISCs were mainly reduced in dyslexic compared
system and behavior (2021), Vol. 135 (33387899) (11 to typical readers in delta (0.5-4 Hz) and high gamma
citations) (55-90 Hz) frequency bands. In the theta (4-8 Hz), beta
(12-25 Hz), and low gamma (25-45 Hz) bands, dyslexics
had enhanced ISCs to speech compared to controls.
Atypical MEG inter-subject correlation during Furthermore, we found that ISCs across both groups
listening to continuous natural speech in dyslexia were associated with phonological processing, techni-
(2020) cal reading, and working memory. The atypical ISCs
to natural speech in dyslexics supports the temporal
Thiede, A; Glerean, E; Kujala, T; Parkkonen, L sampling deficit theory of dyslexia. It also suggests
over-synchronization to phoneme-rate information in
Cognitive Brain Research Unit, Department of Psychology speech, which could indicate more effort-demanding
and Logopedics, Faculty of Medicine, University of Helsinki, sampling of phonemes from speech in dyslexia. These
Finland. Electronic address: [email protected]; Depart- irregularities in parsing speech are likely some of the
ment of Neuroscience and Biomedical Engineering, School complex neural factors contributing to dyslexia. The
of Science, Aalto University, Finland; Department of Neu- associations between neural coupling and reading-
roscience and Biomedical Engineering, School of Science, related skills further support this notion.
Aalto University, Finland; Aalto Neuroimaging Infrastructure,
School of Science, Aalto University, Finland Keywords: Dyslexia, Inter-subject correlation, Magnetoen-
cephalography, Natural speech, Reading skills
ABSTRACT Listening to speech elicits brain activity
time-locked to the speech sounds. This so-called neural NeuroImage (2020), Vol. 216 (32294536) (9 citations)

 ontents  Index 111
C