Biological psychology may be looked at as a hybrid of neuroscience and psychology. Practitioners of biological psychology may use their knowledge of the brain, from neurotransmitters to the cerebral cortex to treat their patients. Others may use this knowledge to search for biological causes for common mental illnesses, such as depression and schizophrenia.
Many psychologists focus largely on the mental processes of their patients. Biological psychologists work on the basis that there is an organic basis to mental processes, and that this requires them to understand the way that mental processes are instansiated in the brain. They recognize that treating the organic problem may be accomplished by talking as well as drugs. Eric Kandell is a great proponent of this theory.