Neural evidence of allophonic perception in children at risk for dyslexia

Abstract

Learning to read is a complex process that develops normally in the majority of children and requires the mapping of graphemes to their corresponding phonemes. Problems with the mapping process nevertheless occur in about 5% of the population and are typically attributed to poor phonological representations, which are--in turn--attributed to underlying speech processing difficulties. We examined auditory discrimination of speech sounds in 6-year-old beginning readers with a familial risk of dyslexia (n=31) and no such risk (n=30) using the mismatch negativity (MMN). MMNs were recorded for stimuli belonging to either the same phoneme category (acoustic variants of /bə/) or different phoneme categories (/bə/ vs. /də/). Stimuli from different phoneme categories elicited MMNs in both the control and at-risk children, but the MMN amplitude was clearly lower in the at-risk children. In contrast, the stimuli from the same phoneme category elicited an MMN in only the children at risk for dyslexia. These results show children at risk for dyslexia to be sensitive to acoustic properties that are irrelevant in their language. Our findings thus suggest a possible cause of dyslexia in that they show 6-year-old beginning readers with at least one parent diagnosed with dyslexia to have a neural sensitivity to speech contrasts that are irrelevant in the ambient language. This sensitivity clearly hampers the development of stable phonological representations and thus leads to significant reading impairment later in life.

Increased Response to Altered Auditory Feedback in Dyslexia: A Weaker Sensorimotor Magnet Implied in the Phonological Deficit

“…This theory suggests that speech perception is not degraded in DD on an acoustic level, but instead, not adequately attuned to the phonetic contrasts present in the native language. This hypothesis has further been supported using behavioral and neuroimaging measures in children at risk for DD (Noordenbos, Segers, Serniclaes, Mitterer, & Verhoeven, 2012a, 2012b. With regard to speech production, it has been shown that both articulatory skills (Catts, 1986(Catts, , 1989 and oral motor skills are impaired in people with DD (Malek, Amiri, Hekmati, Pirzadeh, & Gholizadeh, 2013;Smith, Roberts, Lambrecht-Smith, Locke, & Bennett, 2006).…”

Aplicabilidade do Mismatch Negativity na população infantil: revisão sistemática de literatura

“…(25) Netherland To verify the speech sound discrimination, through the MMN, in children at risk for dyslexia.…”

“…Regarding the place of publication, most articles, totaling 6 (21,28,35,36,38,39) , were developed in Finland. Three articles were written in Brazil (4,12,19) , 3 in the Netherlands (20,23,25) , 3 in the United States (31,32,34) and 3 in France (26,29,30) . Studies have also been found in China (24,27) , Germany (33) , Canada (22) and Israel (37) .…”

“…The participants' ages ranged from 2 months (23) to 12 years of age (4,12,19,22,35,37) . Regarding the parameters used to perform the MMN, most of the research used the speech stimulus (4,(20)(21)(22)(23)(24)(25)(26)30,(32)(33)(34)(35)(36) and other studies opted to perform the MMN with tone burst stimulus (12,19,22,(27)(28)(29)31,(37)(38)(39) . Regarding the tone burst stimulus, it was verified that some studies evaluated with frequency variation (12,(27)(28)(29)31,(37)(38)(39) and 1, by duration and frequency (19) .…”

“…Only one article (30) evaluated children without auditory complaints and without communication disorders, neurological or genetic alterations. The other articles included in this study investigated MMN responses in specific samples in the child population: children with reading and writing impairment (12) , attention deficit hyperactivity disorder (ADHD) (19) , language specific disorder (ADL) (4.32) , auditory processing disorders (4.22) , dyslexia, or presenting a risk factor for that (20,(23)(24)(25)(26)28,33), repetitive otitis media(21), autism (29,34) , stuttering (31) , depressed children (35) , premature and low weight children (28,36) , children with cleft lip and / or palate (27,38) , socially isolated children (37) , children with hearing loss (22) , children with aphasia (39) . Considering that a great part of the studies sought to perform evaluation in individuals with peculiar characteristics, 20 of them (4,(19)(20)(21)(22)(23)(24)(25)(26)(27)29,(31)(32)(33)(34)(35)(36)(37)(38)(39) also included, in their method...…”