Modulation of temporal resolution and speech long-latency auditory-evoked potentials by transcranial direct current stimulation in children and adolescents with dyslexia.

In recent years, transcranial direct current stimulation (tDCS) has been used as a safe and non-invasive method for children and adolescents with dyslexia. Our aim in this study was to investigate the effect of tDCS on variables of temporal resolution and speech long-latency auditory-evoked potentials with two electrode arrays on superior temporal gyrus (STG). A total of 17 children and adolescents with dyslexia (age 9-12 years) were included in our study. All participants underwent the gap in noise (GIN) test and long-latency auditory-evoked potentials recording at baseline without applying tDCS, sham (placebo), and after 20 min of exposure to two different tDCS polarities: anode of tDCS on left STG/cathode on the right shoulder and anode on the left STG/cathode on right STG to enhance left lateralization. Our results showed significant decreases in the threshold value and increases in the percentages of correct responses in the GIN test. We also found reduced latency and increased amplitude of the P1, N1, and P2 waves in two stimulation polarities compared with baseline and sham. Our findings indicate the potential role of tDCS on improving the characteristics of central auditory processing, especially temporal information processing in children and adolescents with dyslexia, and could introduce a new strategy to facilitate the rehabilitation of central auditory processing disorders in future.

Auditory temporal processing abilities in early azari-persian bilinguals.

INTRODUCTION: Auditory temporal resolution and auditory temporal ordering are two major components of the auditory temporal processing abilities that contribute to speech perception and language development. Auditory temporal resolution and auditory temporal ordering can be evaluated by gap-in-noise (GIN) and pitch-pattern-sequence (PPS) tests, respectively. In this survey, the effect of bilingualism as a potential confounding factor on auditory temporal processing abilities was investigated in early Azari-Persian bilinguals. MATERIALS AND METHODS: In this cross-sectional non-interventional study, GIN and PPS tests were performed on 24 (12 men and 12 women) early Azari-Persian bilingual persons and 24 (12 men and 12 women) Persian monolingual subjects in the age range of 18-30 years, with a mean age of 24.57 years in bilingual and 24.68 years in monolingual subjects. Data were analyzed with t-test using SPSS software version 16. RESULTS: There was no statistically significant difference between mean gap threshold and mean percentages of the correct response of the GIN test and average percentage of correct responses in the PPS test between early Azari-Persian bilinguals and Persian monolinguals (P≥0.05). CONCLUSION: According to the findings of this study, bilingualism did not have notable effect on auditory temporal processing abilities.