E　　Fear may be felt in the heart as well as in the head, according to a study that has found a link between the cycles of a beating heart and the chance of someone feeling fear.　　Tests on healthy volunteers found that they were more likely to feel a sense of fear at the moment when their hearts are contracting(收缩) and pumping blood around their bodies, compared with the point when the heartbeat is relaxeD、Scientists say the results suggest that the heart is able to influence how the brain responds to a fearful event, depending on which point it is at in its regular cycle of contraction and relaxation.　　Sarah Garfinkel at theBrighton and Sussex Medical School said: "Our study shows for the first time that the way in which we deal with fear is different depending on when we see fearful pictures in relation to our heart."　　The study tested 20 healthy volunteers on their reactions to fear as they were shown pictures of fearful faces.Dr Garfinkel said, "The study showed that fearful faces are better noticed when the heart is pumping than when it is relaxeD、Thus our hearts can also affect what we see and what we don’t see - and guide whether we see fear."　　To further understand this relationship, the scientists also used a brain scanner(扫描仪) to show how the brain influences the way the heart changes a person’s feeling of fear."We have found an important {{U}}mechanism{{/U}} by which the heart and brain ‘speak’to each other to change our feelings and reduce fear,"Dr Garfinkel saiD、　　"We hope that by increasing our understanding about how fear is dealt with and ways that it could be reduced, we may be able to develop more successful treatments for anxiety disorders, and also for those for those who may be suffering from serious stress disorder." Which of the following is closest in meaning to "mechanism" in Paragraph 6