Components of Evoked Potentials in Frontal Cortex Areas Associated with Image Classification and Independent of Physical Characteristics of Stimuli

Currently, there is a problem of increasing the objectivity of electrophysiological methods for assessment of visual acuity. The purpose of this work: to study the characteristics of cognitive evoked potentials associated with events in the frontal areas of the brain in the tasks of images classification of objects by semantic features. We used visual stimuli, divided into the following classes: by semantic features – into living and nonliving objects, and by spatial frequency ranges – into broadband contour images (white on a black background) and narrowband, in which the low-frequency or high-frequency ranges were isolated by digital filtration. The prepared images were presented to the subjects on the display. In each series of studies, the subjects were instructed to classify the images by the features of “living/nonliving” object, regardless of the physical characteristics of the stimuli. It was shown that the P200 component of evoked potentials in the ventrolateral areas of the frontal cortex depends on the semantic properties of the stimuli – images of animate and inanimate objects and does not depend on such physical characteristics as the presence/absence of high-frequency or low-frequency filtering. In this paper, as a result of the analysis of individual data in two series of studies, the results of measurements of the amplitudes and latent periods for the P200 component of evoked potentials for different (by semantics) classes of contour images with high-frequency and low-frequency filtering at selected several individual spatial frequencies and contour unfiltered images with different instructions to the subjects are presented. The obtained results may be used in the development of a new additional method for assessing visual acuity using visual evoked potentials.