The Activity of Human Mirror Neurons during Observation and Time Perception
The aim of the investigation was to study the activity of human mirror neurons during observation and perception of short time intervals depending on brain laterality. Materials and Methods. The study involved young male volunteers aged 18-27 years. During the preliminary examination, the features of brain laterality were investigated determining the dominant hand (by questioning) and the language-dominant hemisphere (dichotic test). EEG was recorded using the 10-20% system in frontal, central, temporal, parietal, and occipital leads during observation and measurement of short time intervals, observation and reproduction of a five-second rhythm. To study spatial localization of mirror neurons, in some experiments, brain activity was analyzed during observation and time perception using functional magnetic resonance imaging (fMRI). Mu rhythm depression and cortical interactions between the central and other cortical zones at mu frequency were used as EEG markers of mirror neuron activation. Results. It has been found that observation and execution of actions related to time perception by the subjects are accompanied by EEG mu rhythm depression and, most often, increased levels of cortical connections at mu frequency. The nature of these changes depends on mu frequency, brain laterality, the type and stage of the performed activity. The results of fMRI scanning during observation and time perception show that time perception processes actually involve two systems working together. They are the mirror neuron system including areas of the premotor, motor, sensorimotor and supplementary motor cortex as well as areas of the putamen, the caudate nucleus, the supramarginal gyrus, the temporal lobes of the brain, and the timing system including areas of the callosal gyrus, the left thalamus, the temporal lobes of the brain, the visual cortex, the precuneus and the cerebellum. The results of the study have significant theoretical importance for understanding the role of mirror neurons in time perception processes.