Suppression of mu rhythm during exposure to social anxiety related stimuli

Abstract

The so-called mu rhythm in electroencephalography is an oscillation pattern characterized by the frequency domain in the band 8-13 Hz and 15-25 Hz. Inhibition of this pattern of activity has been associated with the activity of mirror neurons in motor and premotor areas of the cortex cerebral. Mirror neurons, in turn, have been related to empathic ability, which capacity may be altered in social anxiety. The aim of the project was to compare the patterns of cortical activity in individuals with high and low levels of social anxiety during the observation of a scene capable of generating social anxiety filmed in two situations: in the third person (when empathic capacity should be evoked) and in the first person (when only possible feelings of self-threat should be evoked). The study involved 70 normal volunteers selected and, from the application of the Liebowitz scale to evaluate social anxiety and the EMRI scale for the evaluation of empathic capacity, 16 volunteers were selected, 8 with the highest scores on these scales and 8 with the lowest scores. Initial analysis of the electroencephalographic tracing of all volunteers did not identify patterns of alpha rhythm power distribution in fronto-parietal regions, which could suggest a pattern of activity associated with the characteristic mu rhythm of mirror neurons. However, a significant difference was found in the comparison between activity patterns associated with observation of first and third person videos (p = 0.007). This difference was also relevant in occipital regions, which could be related to the visual stimulation inherent to the presented stimuli. Therefore, it was not possible to establish a clear correlation between social anxiety traits and empathy with possible mirror neuron activity (through inhibition of mu rhythm). The study, however, showed a significant statistical difference between the patterns of cortical activity associated with the observation of first and third person scenes, regardless of the anxious features. It should be noted that the visual stimulus used may have been excessive, inducing cortical activities linked to visual perceptual activity independent of the meaning or context sought to convey to the observer. The advance of the investigation of the hypothesis explored in this project will require new studies eventually including patients with clinically relevant levels of social anxiety and the simplification of the stimuli used.