Sensitivity of the human mirror neuron system for abstract traces of actions: An EEG-study

Clinical EEG of Rett Syndrome: Group Analysis Supplemented with Longitudinal Case Report

Rett syndrome (RTT), a severe neurodevelopmental disorder caused by MECP2 gene abnormalities, is characterized by atypical EEG activity, and its detailed examination is lacking. We combined the comparison of one-time eyes open EEG resting state activity from 32 girls with RTT and their 41 typically developing peers (age 2-16 years old) with longitudinal following of one girl with RTT to reveal EEG parameters which correspond to the RTT progression. Traditional measures, such as epileptiform abnormalities, generalized background activity, beta activity and the sensorimotor rhythm, were supplemented by a new frequency rate index measured as the ratio between high- and low-frequency power of sensorimotor rhythm. Almost all studied EEG parameters differentiated the groups; however, only the elevated generalized background slowing and decrease in our newly introduced frequency rate index which reflects attenuation in the proportion of the upper band of sensorimotor rhythm in RTT showed significant relation with RTT progression both in longitudinal case and group analysis. Moreover, only this novel index was linked to the breathing irregularities RTT symptom. The percentage of epileptiform activity was unrelated to RTT severity, confirming previous studies. Thus, resting EEG can provide information about the pathophysiological changes caused by MECP2 abnormalities and disease progression.

The Impact of Motor Imageries on Aesthetic Judgment of Chinese Calligraphy: An fMRI Study

Previous behavioral studies on aesthetics demonstrated that there was a close association between perceived action and aesthetic appreciation. However, few studies explored whether motor imagery would influence aesthetic experience and its neural substrates. In the current study, Chinese calligraphy was used as the stimuli to explore the relationship between the motor imagery and the aesthetic judgments of a participant using functional magnetic resonance imaging. The imaging results showed that, compared with the baseline, the activation of the brain regions [e.g., anterior cingulate cortex (ACC), putamen, and insula] involved in perceptual processing, cognitive judgments, aesthetic emotional, and reward processing was observed after the participants performed motor imagery tasks. The contrast analyses within aesthetic judgments showed that the kinesthetic imagery significantly activated the middle frontal gyrus, postcentral gyrus, ACC, and thalamus. Generally, these areas were considered to be closely related to positive aesthetic experience and suggested that motor imagery, especially kinesthetic imagery, might be specifically associated with the aesthetic appreciation of Chinese calligraphy.

Mu-Suppression as an Indicator of Empathic Processes in Lesbian, Gay, and Heterosexual Adults

Self-reported empathy differs with gender and sexual orientation. The current study investigated whether mu-suppression, reflecting brain activity especially related to state empathy, also is modulated by gender and sexual orientation. Pictures of painful and non-painful actions were presented to 20 lesbians, 20 gay men, 20 heterosexual men and 20 heterosexual women, while EEG was recorded. Individual peak frequencies of mu-activity (electrodes C3, C4) were detected within the 6-11 Hz band for each participant, and mu-suppression indices were calculated. Further, verbal indicators of state empathy (pain ratings) and compassion were assessed. Only heterosexual individuals showed the typical pattern of enhanced mu-suppression in response to painful relative to non-painful pictures. Lesbian women and gay men did not show a differential mu-response. Moreover, they felt less compassion compared to heterosexual individuals. In line with this finding, the more compassion the participants reported, the stronger the mu-suppression in response to painful relative to non-painful pictures was. Pain ratings did not vary with sexual orientation. The lesser compassion reported by lesbian women and gay men is discussed as a mediator of their non-differential mu-suppression response. It is hypothesized that this pattern might relate to gay men and lesbian women tending to perceive the anonymous depicted actors as outgroup members, hence showing less compassion and reduced mu-suppression. As empathy is often related to negative feelings (empathic stress), a clear distinction between individuals to empathize with versus individuals not to emphasize with may well be an adaptive feature in same-sex oriented individuals.

Children's mu suppression is sensitive to witnessing others' social victimization

Empathy has been a key focus of social, developmental, and affective neuroscience for some time. However, research using neural measures to study empathy in response to social victimization is sparse, particularly for young children. In the present study, 58 children's (White, non-Hispanic; five to nine years old) mu suppression was measured using electroencephalogram methods (EEG) as they viewed video scenarios depicting social injustices toward White and Black children. We found evidence of increased mu suppression in response to social victimization; however, contrary to well-documented findings of ingroup racial bias in empathic responses among adults, we found no evidence of racial bias in mu suppression in young children. Implications of these findings for neuroscience research on empathy and the development of ingroup bias are discussed.

Clarifying the relationship between trait empathy and action-based resonance indexed by EEG mu-rhythm suppression

Sensorimotor resonance, the vicarious activation of the sensory motor system during observation of another's actions, is thought to contribute to important social functions including empathy. Previous research has shown that sensorimotor resonance, as measured by suppression of the electrophysiological (EEG) mu rhythm, is predicted by trait empathy, but findings are inconsistent. Here we report data from a high-powered study (N = 252) to clarify the relationship between sensorimotor resonance as indexed by mu suppression during action observation and trait empathy as measured by the well-established Interpersonal Reactivity Index (IRI). Our initial pre-registered analyses at central electrode locations indicate that sensorimotor resonance is unrelated to general trait empathy or its sub-facets, however, these effects could not be isolated from attention-related occipital alpha. An additional non-registered analysis using Independent Component Analysis (ICA) to look at the isolated central mu-component clarified the relationship. Results confirmed the lack of a relationship between the mu-component and the perspective taking, personal distress, or fantasy facets of the IRI, but suggest a possible association with empathic concern such that greater resonance is associated with greater empathic concern. These results question the previously assumed relationship between trait empathy and sensorimotor resonance and highlight the need to investigate experience sharing tendencies in the context of simulation-based resonance.

Childhood emotional invalidation and right hemispheric mu suppression during a pain empathy task: An EEG study

Empathy is a critical aspect of social behavior, and impairment in empathic processing is linked to hindered social interactions and several disorders. Despite much interest in this topic, our understanding of the developmental and neural involvement for empathic processing is limited. Recent evidence suggests the Mirror Neuron System (MNS) may play a role in this behavior, and that mu rhythm suppression found over the sensorimotor cortices may be a proxy for the MNS. Therefore, we aimed to measure mu rhythm oscillations in response to empathic processing during observation of painful action-based situations using electroencephalogram (EEG). Our second goal was to examine how perceived parental emotional invalidation (EI) during childhood may relate to empathy and influence mu suppression. Our results showed that mu rhythm suppression was strongest over the right hemisphere. EI had a significant influence on this suppression between painful and non-painful images, and was negatively correlated with behavioral measures of empathy. Our findings suggest that perceived childhood EI may decrease empathizing abilities and influence neural responses to the painful experiences of others. Implications from this study could entail clinical intervention targeted at emotional invalidation to foster the healthy development of empathy.

Toward Model Building for Visual Aesthetic Perception

Several models of visual aesthetic perception have been proposed in recent years. Such models have drawn on investigations into the neural underpinnings of visual aesthetics, utilizing neurophysiological techniques and brain imaging techniques including functional magnetic resonance imaging, magnetoencephalography, and electroencephalography. The neural mechanisms underlying the aesthetic perception of the visual arts have been explained from the perspectives of neuropsychology, brain and cognitive science, informatics, and statistics. Although corresponding models have been constructed, the majority of these models contain elements that are difficult to be simulated or quantified using simple mathematical functions. In this review, we discuss the hypotheses, conceptions, and structures of six typical models for human aesthetic appreciation in the visual domain: the neuropsychological, information processing, mirror, quartet, and two hierarchical feed-forward layered models. Additionally, the neural foundation of aesthetic perception, appreciation, or judgement for each model is summarized. The development of a unified framework for the neurobiological mechanisms underlying the aesthetic perception of visual art and the validation of this framework via mathematical simulation is an interesting challenge in neuroaesthetics research. This review aims to provide information regarding the most promising proposals for bridging the gap between visual information processing and brain activity involved in aesthetic appreciation.