April 24, 1998

Student-invited forum probes basis of mood, emotion

Student-invited forum probes basis of mood, emotion

Insights from nationally renowned neurobiologists into how the human body creates and processes emotions and mood took center stage at last week's Joel G. Hardman Student-Invited Pharmacology Forum.

Titled "The Biological Basis of Emotion and Mood," this annual student-invited forum last year was named in honor of Hardman, previously chair of Pharmacology and recently retired as associate vice chancellor for Health Affairs at Vanderbilt University Medical Center.

"We have always valued the impact Joel Hardman has had on us as pharmacology researchers, and this is our way repaying that guidance," said Lee E. Limbird, interim chair of Pharmacology and associate vice chancellor for Research.

Prior to the lecture portion, Pharmacology graduate students John Partridge, Nicole Schramm, and Matt Wilson presented the 1998 Teaching Award in Pharmacology to Limbird.

"The breadth of quality instructors in the Department of Pharmacology makes choosing a recipient very difficult, but Dr. Limbird has always taken the time to listen to students," said Schramm.

Time with students is beneficial to Limbird as well.

"I have always thought teaching was the best way to learn," said Limbird.

James L. McGaugh, director of the Center for Neurobiology of Learning and Memory at the University of California in Irvine, presented a paper focused on the effects of hormones on the amygdala, an almond-shaped mass in each of the cerebral hemispheres that affects mood, emotion and memory. His topic was "Stress Hormones and Brain Systems Regulating Long Term Memory."

"When I received the invitation to come here and speak I instantly accepted because if the request came from the students it had much more power for me," said McGaugh.

McGaugh's research has shown that hormones injected directly into the amygdala improve memory after a mouse has learned to navigate a maze.

"All experiences are not equally strong in our minds. This research points toward the amygdala as one of the mechanisms that controls how powerful a particular memory is in our minds," said McGaugh.

A better understanding of the amygdala¹s role in memory systems may one day allow researchers to improve memory through drugs that stimulate the amygdala, McGaugh told the Light Hall audience.

Bruce S. McEwen, Ph.D., professor and head of the Harold and Margaret Miliken Hatch Laboratory of Neurobiology, also spoke; his topic was "Sex, Stress, and the Hippocampus."

McEwen focused on the role of stress on the nerves in the hippocampus, a part of the brain that is involved in emotion and mood. In animal models, as stress levels increase, the neurons in the hippocampus remodel themselves, losing branches and, in some cases, dying.

"One interesting finding was that raised estrogen levels produced synaptic genesis or a production of the synapses that had been lost when the subject underwent stress," said McEwen.

Through his research, McEwen has also found that neurons in women are less likely to deteriorate because of higher levels of estrogen. When McEwen gave estrogen therapy to stressed male animals, their neurons partially regenerated themselves, although prolonged stress resulted in permanent loss of neurons.

Although this research is still in the very early stages, it shows promise to improve response to stress.

Dr. Rene Hen, Ph.D., associate professor of Pharmacology at the Center for Neurobiology and Behavior at Columbia University, also spoke at the forum; his presentation was "The Role of Serotonin Receptors in Modulating Aggressive Behavior."

Hen¹s research focuses on the role of the serotonin receptors 5-HT1a and 5-HT1b in aggressive behavior. Hen has knocked out the receptors in mice models and found that low levels of these receptors cause impulsive aggressive behavior.

"The mice in which these genes were knocked out were far more aggressive when we put strange mice into their areas. They would attack the other mice and their attacks would last much longer," said Hen.

Further studies by Hen into the role of the 5-HT1a and b receptors could lead to insights into how to better control aggressive behavior and what levels of these receptors are needed to control aggressive impulses.