An experimentаl grоup оf rаts is injected IP (intrаperitоneally) with a drug that potently blocks mRNA transcription. A control group of rats was injected with saline IP. The same day as the treatments, the rats were trained on a water maze memory task. Compared to the controls, the drug-treated animals performed the same on the maze task when tested later the same day, but performed poorly compared to controls when tested the following day. (NOTE: the drug is able to freely pass into the brain from the circulation] Based on the results of this experiment, which of the following statements must be TRUE regarding the mechanisms involved?