Findings help identify mechanism of age-related memory deficits, highlight the importance of sleep for memory

Aging impairs the consolidation of memories during sleep, a process important in converting new memories into long-term ones, according to new animal research in the July 30 issue of The Journal of Neuroscience. The findings shed light on normal memory mechanisms and how they are disrupted by aging.

During sleep, the hippocampus, a brain region important in learning and memory, repeatedly "replays" brain activity from recent awake experiences. This replay process is believed to be important for memory consolidation. In the new study, Carol Barnes, PhD, and colleagues at the University of Arizona found reduced replay activity during sleep in old compared to young rats, and rats with the least replay activity performed the worst in tests of spatial memory.

Barnes and colleagues recorded hippocampal activity in 11 young and 11 old rats as they navigated several mazes for food rewards. Later, when the animals were asleep, the researchers recorded their hippocampal activity again. In the young animals, the sequence of neural activity recorded while the animals navigated the mazes was repeated when they slept. However, in most of the old animals, the sequence of neural activity recorded during sleep did not reflect the sequence of brain activity recorded in the maze. "These findings suggest that some of the memory impairment experienced during aging could involve a reduction in the automatic process of experience replay," said Michael Hasselmo, DPhil, at Boston University, an expert unaffiliated with the study.

Animals with more faithful sleep replay also performed better on memory tests. The researchers tested the same 22 rats on a spatial learning and memory task. Consistent with previous research, the young rats recalled the solution to the spatial task faster and more accurately than the old rats. In the old group, the researchers found that the top performers in the spatial memory task were also the ones that showed the best sleep replay. Irrespective of the animal's age, the researchers found that animals who more faithfully replayed the sequence of neural activity recorded in the maze while asleep also performed better on the spatial memory task. "This is the first study to suggest that an animal's ability to perform a spatial memory task may be related to the brain's ability to perform memory consolidation during sleep," said study author Barnes.

Identification of the specific memory deficit present in the aging brain may be a first step to preventing age-related memory loss. "This study's findings could inspire the development and testing of pharmacological agents designed to enhance memory replay phenomena," Hasselmo said.

Despite the fact that pediatricians recommend no screen media exposure for children under age 2, three-quarters of very young children in America live in homes where the television is on most of the time, according to research. A new study has found that leaving your TV set on disrupts young children while they are playing, even if the channel is tuned to adult shows. This means that simply having the TV on, even in the background, may be detrimental to children's development. The study, conducted by researchers at the University of Massachusetts, is published in the July/August 2008 issue of the journal Child Development.

The researchers looked at 50 children ages 1, 2, and 3. Each child came to a lab with a parent and was invited to play for an hour with a variety of age-appropriate toys. For half the time, a television was on in the room, showing an episode of the adult game show Jeopardy!, with commercials; during the other half hour, the TV was turned off.

Researchers observed the children as they played to determine whether background TV—defined as adult-oriented television that is on and may be watched by older members of the family, but which very young children don't understand and to which they pay little attention—affected the children's behavior during play.

Background TV was found to disrupt the toy play of the children at every age, even when they paid little attention to it. When the television was on, the children played for significantly shorter periods of time and the time they spent focused on their play was shorter, compared to when the TV was off.

"Background TV, as an ever-changing audiovisual distractor, disrupts children's efforts to sustain attention to ongoing play behaviors," according to Marie Evans Schmidt, who is now a research associate at the Center on Media and Child Health at Children's Hospital Boston and is the lead author of the study. "Background TV is potentially a chronic environmental risk factor affecting most American children. Parents should limit their young children's exposure to background television."

Violence between partners, friends and acquaintances appears prevalent both during and before college, according to results of a survey of students at three urban college campuses published in the July issue of Archives of Pediatrics & Adolescent Medicine, one of the JAMA/Archives journals.

The transition from living at home to attending college may increase adolescents' vulnerability to relationship violence, according to background information in the article. Factors associated with this risk include less parental monitoring and support, isolation in an unknown environment and a strong desire for peer acceptance that can change behaviors toward others.

Christine M. Forke, M.S.N., C.R.N.P., of the Children's Hospital of Philadelphia, and colleagues anonymously surveyed 910 undergraduates age 17 to 22 (57.1 percent female) in 67 randomly chosen college classes. The students answered demographic questions about sex, age, race and length of time in school and reported whether and when they had experienced physical, emotional or sexual violence in a relationship. The researchers found that:

• 407 (44.7 percent) of participants experienced relationship violence either before or during college, including 383 (42.l percent) who were victims of such violence and 156 (17.1 percent) of participants who reported perpetrating violence
  
• Rates of both perpetrating and being a victim of relationship violence were higher before college than during college
  
• 53 percent of women and 27.2 percent of men reported victimization
  
• More than half (130 of 227 reports) of the violence experienced during college was related to a partner rather than a friend or acquaintance
  
• Emotional violence was most common before college (21.1 percent), while sexual and emotional violence were equally common during college (12 percent and 11.8 percent)
  
• Men were more likely to perpetrate sexual violence, while women were more likely to perpetrate physical violence

"In conclusion, all forms of relationship violence are prevalent among male and female college students; almost half of the students had experienced relationship violence at some point in their lives, more than one-third had experienced violence before college and one-quarter had experienced violence during college," the authors write.

Emotional violence was the most common type of violence at all ages. "While emotional abuse frequently is not a focus of violence prevention, it can cause poor outcomes and may predispose victims to other forms of violence. Therefore, educational efforts focusing on healthy relationships should begin during childhood," they conclude.