Questions 15-17 (Suggested completion time: 6 minutes) Directions: Read the text about a science discovery. Answer the questions according to the text. Manipulating Memory Memory is notoriously malleable. Our recollections fade and take on new meanings; sometimes we remember things that never even happened. But 15 . Recently, however, scientists have started to grasp and tinker with memory's physical basis. Last year, in work evocative of films such as Eternal Sunshine of the Spotless Mind and Inception, researchers discovered ways to manipulate specific memories in mice using optogenetics, a powerful technique that can trigger nerve cells in animals' brains by zapping them with beams of laser light. In a series of experiments, they showed that they could delete existing memories and "incept" false ones. This year, researchers went even further: switching the emotional content of a memory in mice from bad to good and vice versa. Under the laser, for example, male mice that had once associated a certain room with being shocked were tricked into acting as though they had once met friendly female mice there instead. Whether the mice in these experiments actually experienced vivid false memories or just a fuzzy sense of pleasure or fear is unclear. Nor is it clear whether the findings apply to the tricks of memory so familiar to people. Long-sought therapeutic advances, such as treatments for post-traumatic stress disorder, could remain far off. One thing is certain, however: Once considered beyond scientific dissection, memory is finally starting to yield its secrets.