Abstract
BACKGROUND: To identify threatening emotional information in a natural scene and form a rapid behavioral response, which is crucial for individual survival. The motor cortex is thought to play a key role in this process. However, little research has addressed differences in the motor system responses to valence-specific emotional stimuli across multiple temporal windows. METHODS: Twenty-eight participants were asked to complete the emotional picture classification task, and then triggered the single-pulse transcranial magnetic stimulation in a specific time window after various emotional pictures were presented, to evaluate the excitability of left and right primary motor cortex (M1) in different time windows after emotional picture presentation. RESULTS: In the early time window (150 ms), the right side of M1 was more excited when viewing negative emotional pictures than neutral emotional pictures and positive emotional pictures, while in the late time window (350 ms), the right side of M1 was more excited when viewing negative emotional pictures than neutral emotional pictures, and the excitability of right-side M1 was higher when viewing positive and negative emotion pictures, but there was no significant difference in the excitability of right-side M1 induced by emotional pictures in the medium-term time window (250 ms). CONCLUSION: The response of motor system to emotional stimulation is mainly reflected in the right hemisphere. In the early time window, negative emotional stimuli elicited a stronger response in right M1, whereas in the late time window, positive and negative emotional stimuli elicited a similar response in right M1. These findings may shed light on the neural basis of emotional motor biases, which could be disrupted in mood disorders like depression and anxiety.