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

Neural entrainment to the beat in multiple frequency bands in 6-7-year-old children

Entrainment to periodic acoustic stimuli has been found to relate both to the auditory and motor cortices, and it could be influenced by the maturity of these brain regions. However, existing research in this topic provides data about different oscillatory brain activities in different age groups with different musical background. In order to obtain a more coherent picture and examine early manifestations of entrainment, we assessed brain oscillations at multiple time scales (beta: 15-25 Hz, gamma: 28-48 Hz) and in steady state evoked potentials (SS-EPs in short) in 6-7-year-old children with no musical background right at the start of primary school before they learnt to read. Our goal was to exclude the effect of music training and reading, since previous studies have shown that sensorimotor entrainment (movement synchronization to the beat) is related to musical and reading abilities. We found evidence for endogenous anticipatory processing in the gamma band related to meter perception, and stimulus-related frequency specific responses. However, we did not find evidence for an interaction between auditory and motor networks, which suggests that endogenous mechanisms related to auditory processing may mature earlier than those that underlie motor actions, such as sensorimotor synchronization

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

Neurokognitív integrációs folyamatok, nyelvfejlődés és nyelvi zavarok = Neurocognitive integration processes, language development and language disorders

A pályázatban olyan integrációs folyamatokat vizsgáltuk, amelyeknek szerepe a nyelvi feldolgozásban kevésbé ismert. Elektrofiziológiai módszerekkel megállapítottuk, hogy a szóhangsúly feldolgozását az akusztikai tulajdonságok, és a hangsúlymintázat reprezentációja együtt határozza meg. A felnőtt adatokat alátámasztják fejlődési és lexikalitás-vizsgálataink. A hangsúly akusztikai modellezésével kimutattuk, hogy a magyar gyerekek érzékenyebbek az ingerkezdet felfutási idejére, az angolok pedig az ingeren belüli modulációra. A nyelvi tapasztalatnak ezt az elemi feldolgozásra való visszahatását eddig nem mutatták ki. A szójelentés és mennyiségtulajdonságok kölcsönhatását számszavakkal vizsgáltuk. A lexikális szemantika szempontjából igazán újdonságnak számító eredmény a szókategóriához kötött keresési folyamatok jelentős eltérésének kimutatása. A lexikai feldolgozás és a szóformák kölcsönhatását vizsgálva az olvasásban működő valószínűségi tanulás új elemeit tártuk fel. Bizonyítottuk a jelentés-feldolgozás és a nyelvtani szerkezetépítés függetlenségét a személy-szám egyeztetés során alany és az állítmány idői távolságát változtatva. A diszlexiásoknál a feldolgozási folyamatok egymásra épülése nem tér el, különbség csupán a feldolgozási időben található. A pályázat összegzéseként a nyelvi feldolgozásért felelős agykérgi hálózat új fejlődési modelljét dolgoztuk ki. A kutatás sikerei új nemzetközi együttműködéseket hoztak. | The aim of this project was to investigate integration processes having a less know nrole in verbal processing. With help of electrophysiological methods we showed that word-stress processing relies on both acoustic properties and stress-pattern. This interpretation of the adult data was strengthened by our developmental studies and lexicality-focused investigations. The acoustic modeling of word stress revealed a particular sensitivity to onset rise-time in Hungarian children and to within stimulus modulation in the English. This effect of language experience on processing basic acoustic feature has not been reported yet. Number-words were used as stimulus material for investigating the association between word meaning and numerosity features. Our new results representing curiosity in lexical semantics suggest a significant variation in word category-related search processes. Studies on the interaction of lexical and word form processing let us to describe new elements of probability learning active during reading. Moreover, it could also be shown that semantic processing and grammatical structure composition were independent in number-person agreement. In dyslexics the interaction of processes is not different; differences are mainly present in the processing time. As a result of the project a new developmental model of the cortical network involved in language processes was developed. The project?s success led to new international collaborations

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

Does Rare Error Count in Impulsivity? Difference in Error-Negativity

High impulsive individuals have problems with self - monitoring and learning from their mistakes. The aim of this study was to investigate whether error processing is impaired in high trait impulsivity, and how it is modulated by the task difficulty. Adults were classified as high ( n = 10) and low ( n = 10) impulsive participants based on the Barratt Impulsiveness Scale, and they participated in a modified flanker task. The flanker trials had three levels of task difficulty manipulated by visual degradation of the stimuli. We measured RTs and ERP components (Ne, Pe) related to erroneous responses. L ow impulsive participants responded significantly faster tha n high impulsive participants . The two groups did not differ in accuracy. The Ne amplitude was smaller in high than in low impulsivity in case of medium and high difficulty levels , but not at low difficulty level . However, the groups did not differ either in the amplitude or in the latency of Pe. We suggest that trait impulsivity is characterized by impaired error detection

Generalized lapse of responding in trait impulsivity indicated by ERPs: the role of energetic factors in inhibitory control

Impaired inhibitory control is one of the still debated underlying mechanisms of trait impulsivity. The Cognitive Energetic Model accounts for the role of energetic factors mediating task performance. The aim of the present study was to compare inhibitory control functions of adults with high and low impulsivity by using a modified Eriksen flanker task. Adults were classified as impulsive (n = 15) and control (n = 15) participants based on the Barratt Impulsiveness Scale. Flanker trials had three levels of required effort manipulated by visual degradation. We analyzed RT, accuracy, and ERPs time-locked to the flanker stimuli. Reaction time of impulsive participants was generally slower than that of controls', but accuracy was similar across groups. N2c showed that monitoring of response conflict was modulated by task requirements independent of impulsivity. The P3 latency was delayed in the impulsive group indicating slower stimulus evaluation. The P3 amplitude was reduced in the control group for moderately degraded incongruent trials suggesting that the attentional resources were employed less. The Lateralized Readiness Potential (LRP) peaked later in the impulsive group irrespective of experimental effects. The amplitude of the positive-going LRP recorded in the incongruent condition was comparable across groups, but the latency was delayed partly supporting a stronger susceptibility to stimulus interference of impulsive participants. Their delayed incongruent negative-going LRP reflected a weaker response inhibition and a slower correct response organization. In conclusion, impaired inhibitory functions in impulsivity could not be unequivocally demonstrated, but we found a generalized lapse of motor activation