Neuromagnetic speech discrimination responses are associated with reading-related skills in dyslexic and typical readers.

Poor neural speech discrimination has been connected to dyslexia, and may represent phonological processing deficits that are hypothesized to be the main cause for reading impairments. Thus far, neural speech discrimination impairments have rarely been investigated in adult dyslexics, and even less by examining sources of neuromagnetic responses. We compared neuromagnetic speech discrimination in dyslexic and typical readers with mismatch fields (MMF) and determined the associations between MMFs and reading-related skills. We expected weak and atypically lateralized MMFs in dyslexic readers, and positive associations between reading-related skills and MMF strength. MMFs were recorded to a repeating pseudoword /ta-ta/ with occasional changes in vowel identity, duration, or syllable frequency from 43 adults, 21 with confirmed dyslexia. Phonetic (vowel and duration) changes elicited left-lateralized MMFs in the auditory cortices. Contrary to our hypothesis, MMF source strengths or lateralization did not differ between groups. However, better verbal working memory was associated with stronger left-hemispheric MMFs to duration changes across groups, and better reading was associated with stronger right-hemispheric late MMFs across speech-sound changes in dyslexic readers. This suggests a link between neural speech processing and reading-related skills, in line with previous work. Furthermore, our findings suggest a right-hemispheric compensatory mechanism for language processing in dyslexia. The results obtained promote the use of MMFs in investigating reading-related brain processes.

Longitudinal changes in the mismatch field evoked by an empathic voice reflect changes in the empathy quotient in autism spectrum disorder.

Autism spectrum disorders (ASDs) are neurodevelopmental conditions with impairments in social communication and interaction. Empathy is the ability to understand and share another person's inner life, and it is an essential process in social cognition, which is deficient in ASD. The mismatch field (MMF) has been used as a neurophysiological marker for the automatic detection of changes in auditory stimuli. In the present study, we focused on long-term changes in MMF evoked by an empathic voice and changes in the empathy quotient (EQ) in ASD during an 8-week clinical trial using oxytocin (OT). Ten males with ASD without intellectual disability participated in this pilot study. The results demonstrated a significant positive correlation between the change in the MMF amplitude in the auditory cortex (i.e., right banks of the superior sulcus) and the change in the EQ score during the 8-week clinical trial, whereas no significant change was observed in the MMF amplitude or EQ score after the administration period of OT. Although we cannot conclude that the observed relationships were caused by OT's effect or by natural changes, our results suggest that MMF evoked by social voice can be a state-dependent marker of empathic abilities in male adults with ASD.

Second-language learning effects on automaticity of speech processing of Japanese phonetic contrasts: An MEG study.

We examined discrimination of a second-language (L2) vowel duration contrast in English learners of Japanese (JP) with different amounts of experience using the magnetoencephalography mismatch field (MMF) component. Twelve L2 learners were tested before and after a second semester of college-level JP; half attended a regular rate course and half an accelerated course with more hours per week. Results showed no significant change in MMF for either the regular or accelerated learning group from beginning to end of the course. We also compared these groups against nine L2 learners who had completed four semesters of college-level JP. These 4-semester learners did not significantly differ from 2-semester learners, in that only a difference in hemisphere activation (interacting with time) between the two groups approached significance. These findings suggest that targeted training of L2 phonology may be necessary to allow for changes in processing of L2 speech contrasts at an early, automatic level.