Dipole analysis of event-related oscillations in anticipation processesстатьяТезисы
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Аннотация:More recent theories of sensory processing emphasize the constructive nature of perception viewing it as an active and highly selective process. Processing of sensory stimuli is controlled by the top-down influences that shape oscillations in the synchrony form revealed in the EEC. However, little is known about the nature of these influences. The present study investigated the contribution of "evoked oscillations" taken by a narrow-band frequency filtering of event-related potentials (ERP) on an anticipation process and a stimulus perception with performing a Go/NoGo visual patterns discrimina¬tion task. The choice of evoked oscillations has been done because their characteristics are well compatible with the pacemaker hypothesis of the rhythms genesis. The method of three-dimensional dipole tracing was combined with structural MRI of human brain to identify localizations of frequency — selective gamma and beta generators. In conditions of purposeful activity it was found that the perception of target and no-target stimulus is controlled by oscillatory activity appeared before stimulus onset. The increasing of frequency — selective gamma and beta generators activity is revealed into the interval 300 ms before stimulus onset in the conditions of the regular presentation of target and no-target stimuli following with probability in 0.5 with the interval in 4 s. The generator activity was estimated by the number of their equivalent dipoles. The amount of activated generators dipoles smoothly grows, reaching a maximum at the moment of stimulus onset, and smoothly decreases after it. The patterns of generators activity into the interval 100 ms before and 100 ms after the stimulus onset are similar in frequency of the activated generators and localizations of their dipoles in brain structures. Frequency-selective generators by a parallel activation at the general frequency and at an identical phase-locking their oscillations to stimulus onset integrate the frontal systems (prefrontal and cingular cortex) with a visual and a temporal cortex, a visual and a motor cortex with a cerebellum already at the early stage of perception. Similar patterns of their activity appear into interval 1000-500 ms before stimuli also. Differential changes in generators activity were revealed with Go vs. NoGo. These finding suggest that activated frequency-selective gamma and beta generators predict the feature of early visual stimulus processing and behavior response.
This work is supported by RFHR, grant 07-06-00421 a (Russia).
doi:10.1016/j.ijpsycho.2008.05.413