Delayed Copying of Unfamiliar Outline Images: Analysis of Stimulus Presentation-Related Potentials

摘要

High-density EEG recordings were made during performance of tasks consisting of delayed motor reproduction of unfamiliar trajectory outline images, with evaluation of event-related potentials (ERP) associated with presentation of these images and a command sound signal (a short sound). A total of 22 right-handed adult subjects took part in the study, which consisted of five blocks of trials with different delays T between the command sound signal and the end of presentation of trajectory outlines (T = 0, 500, 1000, 2000, and 4000 msec). analysis of ERP showed that in contrast to potentials associated with trajectory outline presentation, potentials linked with presentation of the command signals depended on delay duration T. Analysis of the cortical sources of these potentials showed that the changes seen in the sensor space corresponded to a marked monotonic increase in the reactivity of the orbital cortex of the right hemisphere and bilaterally symmetrical increases in the reactivity of the dorsal areas of the sensorimotor cortex. These data are assessed in the framework of the hypothesis of transformations of the internal representation of the trajectory from a sensory-specific format to an abstract sensory- and motor-nonspecific format occurring during the period of holding in working memory.