with the disease or the drugs used to treat it. Because brain activity in epileptics is normal between seizures, “it’s a challenge to develop a drug that will target only the abnormal activity without interfering with normal brain functions.”
ANTICONVULSANT—A drug or procedure able to stop a seizure.
The study of epilepsy in the laboratory begins in vitro. Researchers have learned to simulate a seizure in a culture of neurons, creating a “seizure in a dish.” Unlike bacteria or plant cells, animal neurons when grown in a petri dish (cell model) are capable of forming simple connections that are similar to the connections made between neurons in the brain. This process makes it possible to assess the potential anticonvulsant properties of new drugs. “When trying to characterize the molecular actions of the drugs, we study them in cultured neurons,” Rogawski says. Cultured rat neurons lack the complex connections between brain regions that are present in whole brains or brain slices but are still useful in the early stages of research. After a chemical compound’s activity has been thoroughly studied in a cell model, the researchers use 1/2-mm-thick brain slices from young adult rats. The use of a brain slice (tissue model) allows researchers to understand how electrical activity in one region of the brain affects and interacts with another part of the brain. Researchers are able to obtain dozens of brain slices from a single animal, allowing them to perform several studies using only a single rat brain and reducing the number of animals needed for this type of research. “We can then wash potential drugs over the surface of the slice instead of injecting the whole animal,” Rogawski says. If a new drug looks promising, the researchers then test the drug in animals (organism model). Without administering the drug directly to an animal model, scientists could not be certain that a drug would have therapeutic value or be safe in people. He explains that “the brain is an incredibly complex, interconnected organ. Cells or slices in a dish, while useful in the earlier stages of research, cannot completely predict the effect of a drug on an intact brain.”
IN VITRO—An artificial environment outside a living organism such as a petri dish.
NEURON—A type of cell that conducts electrical impulses; also called a nerve cell; found in the brain, spinal column, and nerves.