[Delayed Copying of Unfamiliar Contour Shapes: Analysis of Potentials Related to Stimuli].

Abstract

The high-density EEG was recorded and ERPs related to showing unfamiliar contour shapes and delivering imperative signal (a short sound) were estimated in the task requiring delayed motor reproduction of these shapes. A total of 22 right-handed adults participated in the experiment. They performed 5-blocks of trials corresponding-to 5 different delays (T= 0; 500, 1000, 2000 4000 ms) between the imperative signal relative to the end of the contour trajectory presentation. An ERP analysis showed that, unlike ERPs related to the contour shape presentation, those related to the imperative signal delivery do change with growing delay T. A subsequent analysis of cortical sources of the ERPs related to the imperative stimulus showed corresponding pronounced grows of reactivity of orbito-frontal cortex of the right hemisphere and a symmetrical bilateral grows of reactivity of dorsal parts of the sensorimotor cortex. The reported findings are discussed in the framework of the proposal according to which the internal representation of a trajectory undergoes a transi- tion from a sensory-specific format towards more abstract neither sensory- nor motor-specific format.