Among the major behavioral changes in schizophrenia are those in attention and habituation, areas in which Freedman has been a leader. They can be reproducibly studied, their anatomy determined, their neuroregulators (transmitters/modulators) identified, and their neural pathways recognized. Some of the behavioral changes, such as smoking and sensory overload, involve neural circuits utilizing acetylcholine and specific receptors including the alpha-7 nicotinic acetylcholine receptor. The neurobiology of specific neurocircuits is considered, such as areas of the hippocampus. Freedman also describes other behaviors and neuronal processes involving such neuroregulators as glutamate, GABA, cannabinoids, serotonin, norepinephrine, and dopamine (now seen in more complex ways). He discusses many behaviors, including paranoia, delusions, and conversions, as well as genetics and epidemiology.