Mirror neurons activated during swallowing and finger movements: An fMRI study ☆

Abstract Objective Neurons in the cerebral cortex, called mirror neurons, have recently been discovered and are activated when another individual's movement is transposed as one's own. As swallowing involves the transfer from a voluntary to a reflex movement, we considered that mirror neurons involved in swallowing may have special characteristics. To examine the characteristics of mirror neurons related to swallowing, we compared mirror neurons involved in swallowing and in finger movements. Materials and methods We examined 12 healthy individuals (6 men, 6 women; average age 23 years; right handed). Brain activities during presentations of swallowing and of finger movements were measured using 1.5-T functional magnetic resonance imaging. Results During presentation of a video for each stimulus, brain activation was observed in areas where mirror neurons are considered to be located, namely bilateral motor association areas (Brodmann area 44: inferior frontal gyrus, BA6: supplementary motor cortex) and bilateral parietal association areas (BA40). Activation was seen in the left ventral posterior cingulate gyrus (BA23) only during presentation of the video about swallowing. Activation of the left BA6 was significant only during presentation of the video about swallowing. Conclusion This activity may not be present during finger movements and may be activations required by mirror neurons during a swallowing movement that involves a shift from a voluntary to a reflex movement.