In accordance with simulation theories of empathy, the somatosensory cortex is involved in the perception of pain of others. Cognitive processes, like perspective taking, can alter empathy-related activity within the somatosensory cortex. The current study investigates whether this modulation is caused by the imagined sensation of pain or by the cognitive load of a perspective-taking task. Applying a within-subject design, participants (N = 30) watched pictures of painful and nonpainful actions, while imagining reduced, normal, or increased pain perception of the observed individual. Mu activity (8-13 Hz), which is inversely correlated with sensorimotor-cortex activity, was measured via EEG. To calculate mu activity (central electrodes) and alpha activity (occipital electrodes), which served as a control for effects of cognitive load, a fast Fourier transform was applied. Mu suppression linearly increased from reduced to normal to increased imagined pain (p < .05), while alpha activity was unaffected by the imagined pain (p > .80). Suppression of the 8-13 Hz band at central and occipital electrodes was stronger in response to painful actions compared to nonpainful actions (p < .01). These results indicate that modulation of mu activity through perspective taking reflects the imagined pain intensity and not the cognitive load induced by the task.

Simulation theories argue that humans simulate motor processes of others to gain information about intentions and emotional states of others. Mu-suppression is a valid electrophysiological correlate of these processes. Mu-activity can be measured via electroencephalography (EEG) in the alpha-band (8-13 Hz) above the sensorimotor cortex and is suppressed when actions are executed or observed. Based on a within-subject design, including 28 participants, it was tested whether the processes measured by mu-suppression could be modulated by empathic top-down-processes. Participants were asked to take the perspective of two actors, telling a story about a sad or neutral life event (video sequences). Afterwards, EEG was measured at central (C3, Cz, C4) and occipital (O1, Oz, O2) electrodes, while participants observed the actors drinking water (standardized video sequences, 8 s duration). Fast fourier transformation showed stronger suppression of power in the alpha-range (relative to baseline) at central and occipital electrodes while the actor with the sad story was observed relative to the actor with the neutral story. Furthermore, measures of state empathy correlated positively with the difference of mu-suppression between executed and observed movements, an indicator of self-other discrimination. Thus, mirror neuron activity measured by mu-suppression is modulated by empathic processes.

The olfactory system and emotional systems are highly intervened and share common neuronal structures. The current study investigates whether emotional (e.g., anger and fear) and physiological (saliva cortisol) stress responses are associated with odor identification ability and hedonic odor judgments (intensity, pleasantness, and unpleasantness). Nineteen men participated in the modified Trier Social Stress Test (TSST) and a control session (cycling on a stationary bike). The physiological arousal was similar in both sessions. In each session, participants' odor identification score was assessed using the University of Pennsylvania Smell Identification Test, and their transient mood was recorded on the dimensions of valence, arousal, anger, and anxiety. Multivariate regression analyses show that an increase of cortisol in the TSST session (as compared with the control session) is associated with better odor identification performance (β = .491) and higher odor intensity ratings (β = .562). However, increased anger in the TSST session (as compared with the control session) is associated with lower odor identification performance (β = -.482). The study shows divergent effects of the emotional and the physiological stress responses, indicating that an increase of cortisol is associated with better odor identification performance, whereas increased anger is associated with poorer odor identification performance.

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Across a wide variety of domains, experts differ from novices in their response to stimuli linked to their respective field of expertise. It is currently unknown whether similar patterns can be observed with regard to social expertise. The current study therefore focuses on social openness, a central social skill necessary to initiate social contact. Human body odors were used as social cues, as they inherently signal the presence of another human being. Using functional MRI, hemodynamic brain responses to body odors of women reporting a high (n = 14) or a low (n = 12) level of social openness were compared. Greater activation within the inferior frontal gyrus and the caudate nucleus was observed in high socially open individuals compared to individuals low in social openness. With the inferior frontal gyrus being a crucial part of the human mirror neuron system, and the caudate nucleus being implicated in social reward, it is discussed whether human body odor might constitute more of a significant and rewarding social signal to individuals high in social openness compared to individuals low in social openness process.