SNM 2007 Image of the Year links brain chemistry to behavior
Crediting molecular imaging for its scientific contributions in discovering the link between genetics and behavior, Henry N. Wagner Jr., SNM past president and historian, presented the award yesterday to scientists from Brookhaven National Laboratory in Upton, N.Y. Wagner has chosen the award winner for 30 years. This image brings together the relationship between the mind and the brain. “The mind is what the brain does,” Wagner said. “This is a coming together of the brain and mind. Chemistry is being measured using [PET imaging and] radiopharmaceuticals. This is the direction that molecular imaging is heading in the not to distant future.”
What Brookhaven researchers have shown through these images is a statistical relationship between brain levels of the enzyme monoamine oxidase (MAO) A and the quantitative assessment of their human subjects' personality. “They used the Tellegen and Waller Multidimensional Personality Questionnaire to measure the volunteers' personality traits and the tracer C-11 clorgyline to measure enzymatic brain MAO-A activity," explained Wagner. Of 240 questions, only those about having a short temper, vindictiveness and enjoying violent movies were related to MAO-A, said Wagner.
Nelly Alia-Klein, PhD, an assistant scientist at Brookhaven, presented a poster illustrating the research that corroborates the relevance of brain enzyme MAO-A in aggressive personality. The four images on the poster include: a view of human genes with high and low concentrations of MAO-A; a brain positron emission tomography (PET) scan showing brain MAO-A activity; and two images of human aggression.
"The study is an example of how scientists are beginning to investigate the complex relationships between an individual's biology and his behavior toward others," said Alia-Klein. "Our study concentrated on how someone's genetic and brain makeup can influence aggressive personality in healthy non-violent volunteers. Our major finding is that having more of the brain MAO A enzymatic activity is related to reporting less aggressive behavior in a personality questionnaire."
She explained that for more than two decades, scientists have studied MAO-A in relation to aggressive and violent behavior. Joanna S. Fowler, an SNM member, member of the National Academy of Sciences and a senior chemist at Brookhaven, developed a way to tag the MAO-A enzyme and study its activity in the brain. "The healthy, nonviolent men who volunteered to do our study had their MAO-A brain activity captured by PET, a camera that uses molecules with special tags to map chemical activity in the brain," explained Alia-Klein. The men then answered a questionnaire that mapped their personality profile.
"We discovered that the amount of MAO-A activity in the brain of 27 healthy men corresponded to the amount of aggression they reported in the questionnaire," said Alia-Klein. "The less MAO-A they had in the brain, the more they answered ‘yes' to statements about taking advantage of others and causing them discomfort.”
Considering what this might mean for the future, Alia-Klein said, "If this model of understanding is tested on individuals who engage in violent behavior (e.g., domestic violence), it could show promise in the future for pharmacological intervention against abnormal violence."