Referent's Lexical Frequency Predicts Mismatch Negativity Responses to New Words Following Semantic Training.

Lexical ERPs (event-related potentials) obtained in an oddball paradigm were suggested to be an index of the formation of new word representations in the brain in the learning process: with increased exposure to new lexemes, the ERP amplitude grows, which is interpreted as a signature of a new memory-trace build-up and activation. Previous learning studies using this approach have, however, mostly used meaningless novel word forms; it therefore remains uncertain whether the increased amplitude simply reflects increased familiarity with the new stimulus or is indeed a reflection of a complete word representation. Here, we used the oddball paradigm to measure the mismatch negativity (MMN) responses to novel word forms before and after semantic training, during which they were associated with previously familiar words of either high or low frequency of occurrence.

The Development of Muscle Fatigue Suppresses Auditory Sensory Gating (P50) during Sustained Contraction.

Our aim was to study the influence of fatigue development on sensory gating during a muscle load. The fatiguing task was sustained contraction of a handgrip dynamometer with 7 and 30% maximum voluntary contraction (MVC). The suppression of P50, an auditory event-related potential, was used as the sensory gating index in the paired-click paradigm with a 500 ms interstimulus interval; the difference between the P50 amplitudes of the first and the second stimuli of the pair was used as the sensory gating index.

[THE EFFECT OF THE WORD FREQUENCY IN RUSSIAN LANGUAGE ON MISMATCH NEGATIVITY (MMN) IN THE EVENT RELATED POTENTIALS (ERP)].

The present study is designed to establish how lexical frequency of Russian words influences the acoustic mismatch negativity (MMN) latency and amplitude. The event related potentials (ERP) were recorded according to the multi-deviant passive odd-ball paradigm by using Russian words with different lexical frequencies and pseudowords. We found that the high-frequency words presentation led to a significantly more pronounced MMN response relative to the low-frequency one.

[Classification of EEG Patterns of Imagined Rhythmic Movements of the Fingers of One Hand].

The article presents the results of classification of EEG patterns registered during imagined rhytmic movements of the fingers of the right hand (little, thumb, index, middle fingers) in 8 healthy subjects. The subjects imagined finger movements in a given rhythm; no external stimuli were used. A two-level committee of classifiers was developed for decoding: the first level included support vector machines and artificial neural networks; the second level included artificial neural network used for generalizing.