Editors: Several researchers from Indiana University are participating in Neuroscience 2007, the annual meeting of the Society for Neuroscience, held this year on Nov. 3-7 in San Diego. Below is information about two poster presentations involving researchers from the Kinsey Institute for Research in Sex, Gender and Reproduction and the School of Health, Physical Education and Recreation at IU Bloomington. The information is embargoed until the date and time of their presentations.
HORMONES, THE BRAIN AND SEX
An Indiana University neuroscientist found that women's brains respond differently to male faces depending on the stage of the their menstrual cycle.
Around the time of ovulation, women showed more activity in brain regions associated with reward and less activity in brain regions associated with inhibition and cognitive control, according to research by Heather Rupp, research fellow at the Kinsey Institute for Research in Sex, Gender and Reproduction at IU Bloomington.
"These findings suggest that women's brain systems that process rewards may be more sensitive around the time that women are likely to conceive," Rupp said. "The heightened sensitivity of this system around ovulation may generalize to other stimuli that activate the same system, such as drugs or alcohol. Therefore, these findings not only add to our basic understanding of the reward system and its role in female sexual behavior, but may also be clinically important; as women may be more likely to engage in risky sexual behavior or could be vulnerable to drug or alcohol abuse at this time."
Rupp used functional magnetic resonance imaging (fMRI) in her study, which found the following:
- Women exhibited greater brain activity in areas related to reward and face processing, including the medial orbitofrontal cortex, hippocampus, and occipital face areas, around the time of ovulation. Also during ovulation, less activity was observed at this time in brain regions associated with inhibition and risk, including the frontal cortex.
- When viewing the faces of men with a risky sexual history, the women exhibited less brain activity in brain regions associated with decision-making and reward, compared to when look at faces of low-risk men. This discrimination was strongest later in the cycle.
- In response to more masculine male faces, women showed more brain activity in areas associated with risk and emotion, such as the anterior cingulate and insula.
Background: The study involved 12 heterosexual women ages 23 to 28 who were not using hormonal contraceptives or in committed relationships. Their brain activity was measured using an fMRI scanner around ovulation and later in the menstrual cycle. While in the scanner, each woman was shown 256 photos of male faces that varied in facial masculinity and sexual risk. A computer morphing program altered the male face photos to appear more or less masculine. Sexual risk information included the man's number of previous sexual partners and typical condom use. The women were asked to indicate on a response paddle how likely they would be to have sex with the man depicted.
Rupp also is a postdoctoral fellow in IU's Common Themes in Reproductive Diversity Program. She can be reached at firstname.lastname@example.org and 812-856-0009. Embargoed until Wednesday, Nov. 7, 1 p.m.
TRAINING QUIETS AGING REFLEXES
Older participants in a 5-week balance class at Indiana University saw their balance improve on average by 19.5 percent. Researchers attribute much of this improvement to training geared toward minimizing the influence of the participants' aging and less reliable reflexes.
Special exercises on a wobble board targeted muscle fibers and motor neurons associated with their gastrocnemius and soleus muscles, which are the calf muscle and the muscle immediately beneath it. These muscles are important for balance because they help people stand upright.
The special exercises were designed to help the participants, ages 80-90, retrain the 1a sensory fiber and motor neurons in the spinal cord in an attempt to have subjects rely less on reflex corrections, which are involuntary, and more on cortical control from the brain, which is much more effective at controlling balance.
Koichi Kitano, a doctoral student in the Department of Kinesiology in IU's School of Health, Physical Education and Recreation and the Program in Neuroscience, said he and his colleagues determined that after training, the reflex measured in the soleus muscle showed little change, but that the changes measured in the gastrocnemius were "significant."
Background: This study is part of a larger research effort by motor control experts at HPER to develop a screening technique that could alert older people to their increased risk for falls. Falls involving a broken bone can be fatal and also can result in a dramatic decline in mobility, health, independence and quality of life as the person changes her lifestyle to avoid more falls. IU researchers have recently found that a psychological inventory that probes such things as planning strategies and short-term memory is surprisingly effective in predicting balance ability. To learn more about this research, visit http://newsinfo.iu.edu/web/page/normal/6532.html.
Kitano's study involved 12 people who participated in a 45-minute balance class three days a week. In addition to stretching and strengthening exercises, they spent 15 minutes of each class using a specially designed wobble board to target the postural and balance muscles. Kitano can be reached at email@example.com. His presentation was Nov. 4.