It means that a control group receives an innocuous medication called a placebo. A placebo looks, tastes, and smells like the experimental medication. The control group serves as a baseline to compare with other groups that receive the drug.
Work Step by Step
The control group received a "false" drug. It looks, tastes, and smells like the real topiramate. In the end of the experiment, the control group was used to be compared to the group that received topiramate.