Variability in natural speech is challenging for the dyslexic brain


Date:
June 25, 2020
Source:
University of Helsinki
Summary:
A new study brings neural-level evidence that the continuous
variation in natural speech makes the discrimination of phonemes
challenging for adults suffering from developmental reading-deficit
dyslexia.



FULL STORY ==========================================================================
A new study brings neural-level evidence that the continuous variation
in natural speech makes the discrimination of phonemes challenging for
adults suffering from developmental reading-deficit dyslexia.


==========================================================================
This may compromise the learning of native language phonemes already at
an early age for infants at familial risk for dyslexia.

Dyslexia is understood to stem from difficulties in phoneme
processing. Natural speech has continuous acoustic variation, and the
phonemes sound different depending on, for example, the word context
or speaker identity. In order to effortlessly understand speech, the
phonemes still have to be detected accurately.

"In our study, dyslexic participants had difficulties, particularly
when acoustic variation was added to the speech sound stream. In the
absence of this variation, neural speech sound processing did not differ between dyslexic and typical readers. This seems to reflect a difficulty
in categorising speech sounds in the native language phoneme classes,"
Dr Paula Virtala from the University of Helsinki explains.

Understanding the neural mechanisms of dyslexia will help in targeting
and designing rehabilitation for children with language development or
reading problems, and in preventing future difficulties early in infants
and small children at familial risk.

EEG revealed differences The study, which was published recently in
Scientific Reports, was conducted by recording the neural activity of
18 dyslexic and 20 typically reading adults with electroencephalography
(EEG).

The participants listened to a stream of Finnish speech sounds at various
pitch levels passively, with their attention directed away from the stimulation, and actively, by pressing a response button when detecting
a change in the speech sounds.

Auditory event-related potentials differed between the two groups in both conditions. Dyslexic participants were also less accurate in detecting
the changes.

"These kinds of studies conducted in adults allow for longer recording
sessions and a broader range of methods compared to studies in
children. We can utilise these findings in our longitudinal DyslexiaBaby study," Paula Virtala explains.

The DyslexiaBaby study is conducted in the Cognitive Brain Research Unit
at University of Helsinki. It follows children's language development, particularly in families with dyslexia. The study is conducted in
collaboration with Helsinki University Hospital and the University
of Jyva"skyla".


========================================================================== Story Source: Materials provided by University_of_Helsinki. Original
written by Miia Soininen. Note: Content may be edited for style and
length.


========================================================================== Journal Reference:
1. P. Virtala, S. Talola, E. Partanen, T. Kujala. Poor neural and
perceptual
phoneme discrimination during acoustic variation
in dyslexia. Scientific Reports, 2020; 10 (1) DOI:
10.1038/s41598-020-65490-3 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200625102522.htm

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