Effects of transcranial electrical stimulation of the right prefrontal and left spindle cortex on the recognition of emotion expression

Introduction. Recognition of facial expressions plays an important role in social interaction. The authors consider the issue of emotion recognition by investigating the work of the brain structures responsible for the perception of emotions of a certain valence. Much data has been accumulated on invasive and noninvasive ways of influencing the functioning of these structures. However, the issue of noninvasive influence on structures that take part in the recognition of facial expressions but are not associated with the recognition of emotions of a particular valence is not sufficiently studied. Objective. To study the peculiarities of the influence of the right prefrontal and left spindle cortex under normal conditions and under conditions of transcranial electrical stimulation on the process of recognizing visual expressions of emotion. Materials and Methods. The study used electroencephalogram recording with subsequent isolation of evoked potentials, as well as transcranial electrical stimulation of the right lateral sulcus (near T4), right prefrontal cortex (near F8), and right lingual cortex (near T6). The study was divided into 3 stages: demonstration of photographs of faces of standardized collections of KDEF, RAFD, WSEFEP, expressing emotions of anger, sadness, joy, fear, surprise, disgust, and neutral emotions, with simultaneous recording of electroencephalography; transcranial electrical stimulation of the experimental group and placebo control group; repeated demonstration of photographs of faces and recording of electroencephalogram. Statistical processing was performed using the ANOVA method for repeated measurements. Results. The volunteers in this study were 60 healthy subjects of both sexes, aged 18 to 26 years. Differences in response time were found depending on whether they belonged to the control or experimental group, as well as differences in the components of the evoked potentials N1, N2, and P2 depending on group membership and the valence of the emotion. Discussion. The results obtained are explained by the fact that structures associated with the recognition of emotions of a particular valence may depend on the functioning of structures not associated with the recognition of emotions of a particular valence, since the latter provide them with information about the perceived stimulus. The dependence of functioning of structures responsible for identification of emotional expressions of a particular valence can be explained by modulation of their functions by brain structures that are not specialized for a particular valence of the perceived emotional expression.