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

Theories of neuroaesthetics assume, that looking at traces of actions used in creating artwork (e.g. brush marks) is associated with a simulation of these actions in the observer's sensorimotor-cortex. The aim of the current study is to dissociate the activation of the sensorimotor-cortex by the observation of action traces from associated visual processes. Twenty-eight participants observed handmade graphics (acrylic paint on paper) of different complexity (line, triangle, shape of a house) and computer-generated counterparts. Central mu-activity, as an index of sensorimotor-cortex activity, and occipital alpha-activity, as an index of visual cortex activity were recorded in the 8-13Hz EEG-band. In line with the hypothesis, mu-activity at electrode C4 is sensitive for the complexity of handmade (p=0.001), but not computer-generated graphics (p>0.500). In contrast, occipital alpha-activity is sensitive for the complexity of both handmade and computer-generated graphics (p<0.001). Furthermore, the more empathic the participants rated themselves, the stronger mu-suppression was induced by handmade graphics compared to computer-generated graphics (electrode C4; r=-0.612, p=0.001). These results support the involvement of the sensorimotor-cortex in the recognition of action traces and strengthen evidence that individuals scoring high in emotional empathy feature a particularly responsive mirror neuron system.