Feline Rage Mirrors Human Anger

Jan. 25, 2008 -- Feline defensive rage, the aggressive cat behavior that recently led to the death of a California zoo visitor by a tiger that felt threatened, is comparable to human rage, both in the way that it emerges and unleashes in the brain, suggests a new study.

Because scientists are gaining a better understanding of the mammalian brain's recipe for rage, violent behavior in humans and other mammals may one day be quelled with improved drug therapies.

For cats, such a drug could prevent the hissing, back arching, ear retraction, claw extensions and fur standing-on-end that are typical indicators of feline defensive rage. In humans, related anger reveals itself with road rage, an impulsive form of anger that involves little or no thought.

"In road rage, the person never thinks about what he is doing but just acts in the way he does because he feels that he has been threatened by someone else and the impulsive behavior represents a way by which he can protect himself from such a threat," co-author Allan Siegel told Discovery News.

"In reality, his actions are usually much more dangerous to him than to the person whom he perceived cut him off on the road," added Siegel, a professor in the Department of Neurology & Neurosciences at New Jersey Medical School in Newark.

Prior studies have suggested that anger is centered in the medial hypothalamus region of the brain, more colloquially known as the midbrain's gray matter. Siegel and his team can even artificially induce anger in cats by electrically stimulating this brain region.

The researchers suspected that certain proteins help to control the process, so after electronically creating feline defensive rage in 10 adult female cats, they introduced a protein, called an interleukin, into the anger region of the cats' brains. As predicted, it fueled the felines' rage.

Siegel explained that the protein somehow attaches to a serotonin receptor. Serotonin is a critical neurotransmitter that helps inhibit everything from sleep to vomiting to sex and hunger in humans.

For anger, the interleukin reacts with the serotonin, causing the neuron to which the serotonin is attached to discharge. Before long, many neurons in the region start to discharge at a high rate, causing the individual to fall into a rage and behave defensively.