Mismatch Negativity (MMN): Komponen Event-Related Potentials (ERP) sebagai Penanda Aktivitas Otomatis Otak dalam Mendeteksi Perubahan

Agar dapat berinteraksi secara efisien terhadap banyaknya informasi sensori, otak memiliki strategi heuristis yang dapat menyaring informasi sekaligus mengarahkan atensi ketika muncul informasi yang penting dan krusial. Penelitian tentang otak telah mengungkapkan salah satu penanda atas sistem tersebut, yang disebut sebagai Mismatch Negativity (MMN). MMN merupakan salah satu komponen dari Event-Related brain Potentials (ERP) yang diasosiasikan dengan penanda sistem pendeteksi perubahan dan pelanggaran tiba-tiba terhadap aturan abstrak dari stimulus suara, dan dapat digunakan sebagai indikator objektif mengenai akurasi diskriminasi suara, sensori memori, maupun proses praatensi. Komponen MMN muncul sebagai gelombang negatif yang terpicu oleh stimulus yang menyimpang dari keteraturan. Metode MMN telah banyak digunakan dalam berbagai bidang penelitian hingga konteks klinis. MMN juga merupakan metode yang sangat bermanfaat untuk menyelidiki mekanisme pemrosesan kognitif pada populasi yang memiliki kesulitan untuk mengikuti prosedur eksperimen, misalnya pada anak-anak, atau pasien klinis karena sifatnya yang otomatis dan tidak membutuhkan atensi. Artikel ini bertujuan untuk memberikan pengenalan mengenai konsep dan prinsip dasar dalam MMN, paradigma eksperimen, hingga contoh aplikasi, dan potensi penelitian yang dapat dilakukan menggunakan metode ini

Predictors of developmental dyslexia in European orthographies with varying complexity

Background: The relationship between phoneme awareness, rapid automatized naming (RAN), verbal short-term/working memory (ST/WM) and diagnostic category is investigated in control and dyslexic children, and the extent to which this depends on orthographic complexity. Methods: General cognitive, phonological and literacy skills were tested in 1138 control and 1114 dyslexic children speaking 6 different languages spanning a large range of orthographic complexity (Finnish, Hungarian, German, Dutch, French, English). Results: Phoneme deletion and RAN were strong concurrent predictors of developmental dyslexia, while verbal ST/WM and general verbal abilities played a comparatively minor role. In logistic regression models, more participants were classified correctly when orthography was more complex. The impact of phoneme deletion and RAN-digits was stronger in complex than in less complex orthographies. Conclusions: Findings are largely consistent with the literature on predictors of dyslexia and literacy skills, while uniquely demonstrating how orthographic complexity exacerbates some symptoms of dyslexia

Saliency or template? ERP evidence for long-term representation of word stress

The present study investigated the event-related brain potential (ERP) correlates of word stress processing. Previous results showed that the violation of a legal stress pattern elicited two consecutive Mismatch Negativity (MMN) components synchronized to the changes on the first and second syllable. The aim of the present study was to test whether ERPs reflect only the detection of salient features present on the syllables, or they reflect the activation of long-term stress related representations. We examined ERPs elicited by pseudowords with no lexical representation in two conditions: the standard having a legal stress patterns, and the deviant an illegal one, and the standard having an illegal stress pattern, and the deviant a legal one. We found that the deviant having an illegal stress pattern elicited two consecutive MMN components, whereas the deviant having a legal stress pattern did not elicit MMN. Moreover, pseudowords with a legal stress pattern elicited the same ERP responses irrespective of their role in the oddball sequence, i.e., if they were standards or deviants. The results suggest that stress pattern changes are processed relying on long-term representation of word stress. To account for these results, we propose that the processing of stress cues is based on language-specific, pre-lexical stress templates