Schizophrenia. Artwork of a man hearing non- existent women's voices. Auditory hallucinations are one of the most common symptoms of schizophrenia. One explanation for this disease is known as the dopamine hypothesis. Dopamine (the molecules at lower left & right) is a type of neurotransmitter. This chemical (tiny red spheres) is released from the ends (synapses) of nerve cells (neurons, upper left & right) when they pass on nerve impulses to other neurons. In schizophr- enia, however, the dopamine-producing neurons of the brain are overactive. This causes the sufferer to lose contact with reality, suffering from confused thoughts and emotional responses.