In social interactions, the values we associate with observed actions can influence how we process others’ behaviors and the decisions we make. Some studies have suggested that different social contexts, and particularly the reward value of perceived actions can modulate motor system activity when observing others’ actions. However, sensitivity to reward magnitude has never been tested in the action observation system. Here we used electroencephalography (EEG) to investigate the independent effects of reward valence and magnitude on the mu rhythm, an index of the motor mirror system, while participants (N=23) passively observed actions that led to high or low rewards or losses. Behavioral measures of social approach/avoidance, theory of mind and empathy were also taken. Results showed that reward valence significantly modulated mu rhythm, where losses led to greater mu suppression, but reward magnitude had no effect. The findings also demonstrated a novel association between the specific reward-related modulation of the mu rhythm and social cognitive skills, particularly cognitive empathy and emotional reactivity. This study provides further evidence for the role of reward processing in the mirror motor system, and highlights the relationship between value-based action perception and social cognitive traits, implicating a role for the mirror system in social decision-making.

The Biased Competition Model suggests that stimuli matching the contents of working memory increase the likelihood that memorymatching items will be attended. According to this account, the representations in working memory create an involuntary capture of attention toward memory-matching items in the visual field. This influential assumption proposed by the biased competition model has been explored in a number of studies, showing that the contents of working memory exert an automatic bias in favor of memory matching items. These studies showed that active maintenance of objects in working memory automatically shift attention toward the memory matching-object and produce a negative early lateralized event related potential (ERP), the N2pc, toward the side of visual field where the memorized item appeared. This component, the N2pc is an important tool to investigate the allocation of attention by working memory representations, especially for the activity the activity that is specific to the hemisphere which is contralateral with respect to the hemifield containing e.g. the to-be-remembered items could be measured. This characteristic of the N2pc facilitates measuring the general direction of attention with fine-grained temporal resolution. Therefore, the N2pc could be used as an index to describe the lateralization effect of memorized items on attention related studies.

The olfactory system is vital mechanism for our survival to interact with the environment, influencing not only on odor detection but also on nutrition, social behavior and well-being. Current findings suggest that before the onset of any cognitive decline reflecting early sign of dementia, dysfunction in the areas processing olfactory information is present at the early stages of Alzheimer’s disease (AD). Behavioral test including thresholds, odor identification, recognition memory tasks are the most common types of odor measurement. However, recent neuroimaging techniques using measures of brain response, including Olfactory Event Related Potentials (OERPs) suggested the potential for detection of AD at the early preclinical stage. The importance of olfactory event related potentials and their relation with AD appear to be very promising.