August 3, 1998
Volume 50, No. 36
Winslow studies brain chemical's role in aggression
Recent shootings in public schools have focused attention on an alarming increase in acts of aggression among the young--especially males. Many experts are looking for the reasons behind this epidemic of violence, including behavioral neuroscientist Jim Winslow, an associate professor at Yerkes.
Winslow recently received a one-year University Research Committee grant of $30,000 for studies on the role of serotonin in the development of alcohol-related aggression among adolescent male rhesus monkeys.
The neurotransmitter serotonin has been linked to a number of mental disorders including anxiety, depression and obsessive-compulsive behavior. "A great deal of clinical evidence in human populations also suggests that a deficit of serotonin may underlie the expression of violent behavior in groups such as criminals and the mentally ill," Winslow said.
His studies will investigate the effects of depleting brain serotonin in juvenile monkeys. The experiments will use toxic doses of methylenedioxy-methamphetamine (MDMA)--a hallucinatory drug known by the street name of "ecstacy"--which kills nerves in the brain that release serotonin.
"One of the goals of the study is to look at what happens to the development of social behavior in juvenile monkeys who have been treated with this drug," Winslow said. "Many of the people abusing this drug now are young people between the ages of 13 and 18, a critical period for development of social behavior and for development of the brain.
He will also focus on alcohol's effect on the social interactions of monkeys. Winslow chose alcohol "because this is the drug most frequently associated with violence, particularly the growing problem of violence among young males in the United States," he said.
The experiments will use four pairs of monkeys. The animals will range in age from 18 months to 2 years old--about 8 or 9 years old in human years-and will be from different family groups. "Rhesus monkeys are ordinarily very social animals and maintain fairly well-defined social structures or dominance hierarchies based on family histories," Winslow explained.
After the initial study on alcohol effects, Winslow will look at how MDMA influences social behavior. The final group of studies will examine how MDMA influences the way alcohol affects social behavior.
"Not everyone who drinks alcohol becomes violent," Winslow said. "The question is, what makes some people violent after they drink alcohol, and is serotonin somehow involved in that?" His hypothesis is that animals treated with MDMA will have a different reaction to alcohol, causing them to be more aggressive in social interactions.
Winslow explained that the aggressive behavior of rhesus monkeys is much less violent than that of humans. "It tends to be threats and postures, rather than guns and knives."
The studies will look at how alcohol influences the typical aggressive interactions that occur in normal social interactions in rhesus monkeys, he said, noting that these are modest approximations of human conditions. "Naturally, all these social interactions will be monitored closely," he said. "If it looks like things are getting out of hand, then we'll separate the animals."
Winslow, who is a faculty member of the Violence Studies Program, has examined alcohol's effects on aggressive behavior in monkeys and MDMA's effect on the development of emotional behavior in rats. "I've looked at pieces of this question over the years," he said. In addition to his work at Yerkes, Winslow is an assistant professor with the Department of Psychiatry and Behavioral Sciences in the School of Medicine, and teaches graduate and undergraduate courses in psychology.