For example, all vertebrate brains use the same neurotransmitter systems. By studying simpler nervous systems we can learn the fundamental principles that govern the function of all brains. An animal model does not have to reproduce all symptoms of a human disorder to be effective. Thus, in studying schizophrenia, we do not have to work with rats that have a major thought disorder and suffer from hallucinations. Rather, we need to work with animals that suffer a specific symptom similar to those suffered by schizophrenic patients.
Schizophrenic patients are unable to filter out certain types of sensory information.
Once this symptom has been produced in the rats, the experimenter can study how other drugs or behavioral manipulations can reduce the symptom. Finding therapies that work in the animal model may one day lead to more effective treatments for human beings.