Impaired auditory frequency discrimination in dyslexia detected with mismatch evoked potentials

Abstract

Deficits in phonological skills appear to be at the heart of reading disability; however, the nature of this impairment is not yet known. The hypothesis that dyslexic subjects are impaired in auditory frequency discrimination was tested by using an attention‐independent auditory brain potential, termed mismatch negativity (MMN) while subjects performed a visual distractor task. In separate blocks, MMN responses to graded changes in tone frequency or tone duration were recorded in 10 dyslexic and matched control subjects. MMN potentials to changes in tone frequency but not to changes in tone duration were abnormal in dyslexic subjects. This physiological deficit was corroborated by a similarly specific impairment in discriminating tone frequency, but not tone duration, which was assessed separately. Furthermore, the pitch discrimination and MMN deficit was correlated with the degree of impairment in phonological skills, as reflected in reading errors of regular words and nonwords. It is possible that in dyslexia a persistent sensory deficit in monitoring the frequency of incoming sound may impair the feedback control necessary for the normal development of phonological skills. Ann Neurol 1999;45:495–503

Auditory sensory deficits in developmental dyslexia: A longitudinal ERP study

“…As the length of the duration deviant was changed from 160 ms in year 1 of the study to 140 ms in year 2, no direct comparison was possible between MMN responses at Phases 1 and 2, even though the standard stimulus remained at 200 ms duration at each test point. Nevertheless, in line with some previous studies (Baldeweg et al, 1999;Huttunen et al, 2007), we found no direct evidence of deficient processing of tone duration in dyslexia.…”

“…The authors interpreted their findings as a speech-specific deficit, however they did not exclude the possibility of a more general deficit in auditory processing. Indeed, deficient pitch (Baldeweg et al, 1999;Kujala et al, 2006) and temporal discrimination (Kujala et al, 2000(Kujala et al, , 2003 have also been reported in dyslexia (for a recent review on theories of dyslexia, including a general acoustic processing deficit account, see Schulte-Körne and Bruder, 2010). Recent results from a multi-feature paradigm in 6 year old children (Lovio et al, 2010) suggest wide-spread auditory deficits in children at risk for dyslexia.…”

O Mismatch Negativity em pacientes com distúrbios do processamento auditivo (central)

“…A second hypothesis is that (C)APD subjects in this study had no frequency deviating pure tone discrimination problems, as was found in Meng et al's study, 28 or duration deviating problems, as seen in Baldeweg et al's 26 and Korpilahti and Lang's studies. 27 Or these subjects might have altered MMN only for verbal sounds, as shown in studies by Schulte-Körne et al, [19][20] Uwer, Albrecht and Suchodoletz, 21 and Sharma et al -We believe, therefore, that the lack of MMN changes in our study may be due to the fact that (C) APD subjects had auditory discrimination difficulties limited to acoustic parameters not assessed in our study.…”

“…In this study, MMN was normal for speech stimuli deviating in terms of the articulation point. 18 The investigation of MMN in (C)APD patients with associated comorbidities due to other diseases shows that MMN was altered for speech stimuli but normal for pure tone stimuli in some studies, [19][20][21][22] that MMN was altered for verbal and non-verbal stimuli in other studies, 23 still others in which MMN was altered for pure tone stimuli with frequency deviations, [24][25] studies in which MMN was altered for pure tones with frequency but not duration deviations, [26][27] studies in which MMN was normal for pure tones with frequency deviations but altered for different compound tone patters, 28 and in studies in which MMN was unchanged for frequency and duration stimuli. [29][30][31][32] Our study aimed to investigate MMN in (C)APD patients, considering the diversity of results in studies of MMN in these patients, as well as the importance of undertaking the electrophysiological evaluation of auditory processing studies.…”

Brain potentials to native phoneme discrimination reveal the origin of individual differences in learning the sounds of a second language

“…In the duration and frequency conditions, participants' discrimination accuracy of duration and frequency changes was evaluated. We chose these parameters because they seem to be relevant for phonemic perception, as shown by several studies that link difficulties in duration and/or frequency coding and speech perception disabilities (30)(31)(32). In each condition, stimuli were presented after an oddball paradigm, in which a tone was presented frequently (standard), whereas three other tones deviating in one parameter (frequency or duration) were presented at a lower probability (deviants).…”