A.The numbers of neurotransmitters and receptor levels differs widely between dog brains and human brains.
B. Alterations in neurotransmitter and receptor levels might be the result of sleep disturbances, not the cause of it.
C.A particular site in the brain's frontal lobe is isolated where the bulk of the neurological damage occurs.
D. Too few acetylcholine, dopamine and norepinephrine neurotransmitters exist in dog brains to establish their role in narcolepsy.
E. An autoimmune dysfunction is conclusively proven to be the cause in a large but incomplete majority of narcolepsy cases.