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November 20, 2013

In Research

‘Seeing’ in the dark?

girl wearing eye tracking visor, waving hand
Study participant Lindsay Bronnenkant demonstrates a task from a new cognitive science study on vision and movement in the lab of Duje Tadin, associate professor of brain and cognitive sciences.

With the help of computerized eye trackers, a cognitive science study indicates that at least 50 percent of people can see the movement of their own hand even in the absence of all light.

“Seeing in total darkness? According to the current understanding of natural vision, that just doesn’t happen,” says Duje Tadin, associate professor of brain and cognitive sciences who led the investigation. “But this research shows that our own movements transmit sensory signals that also can create real visual perceptions in the brain, even in the complete absence of optical input.”

Through five separate experiments involving 129 individuals, the authors found that the eerie ability to see our hand in the dark suggests that our brain combines information from different senses to create our perceptions. The ability also “underscores that what we normally perceive of as sight is really as much a function of our brains as our eyes,” says first author Kevin Dieter, a postdoctoral fellow in psychology at Vanderbilt University.

The study seems to confirm anecdotal reports that spelunkers in lightless caves often are able to see their hands. In other words, the “spelunker illusion,” as one blogger dubbed it, is likely not an illusion after all.

For most people, this ability to see self-motion in darkness probably is learned, the authors conclude. “We get such reliable exposure to the sight of our own hand moving that our brains learn to predict the expected moving image even without actual visual input,” says Dieter.

Tadin, Dieter, and their team from Rochester and Vanderbilt University reported their findings online in Psychological Science.

Read more and watch a video about the research at www.rochester.edu/news.

Depression therapy effective for poor, minority moms

A new study from Rochester psychologists shows that screening for depression and providing short-term, relationship- focused therapy through weekly home visits can relieve depression among minority mothers, even in the face of poverty and personal histories of abuse or violence. Such help can have far-reaching benefits not only for mothers but also for their children, say the authors.

“It’s amazing, really,” says Sheree Toth, lead author and executive director of the University’s Mt. Hope Family Center. “This research tracked a 14-week intervention for mothers who are terribly overwhelmed, surrounded by high-crime neighborhoods, lacking social support, and often traumatized—my fear was, ‘this is never going to work.’”

But to the surprise of Toth and her Rochester team, the series of one-hour therapy sessions relieved depression in participants much better than standard clinic-based care. The study participants also continued to improve eight-months after the treatment ended, regaining a sense of hope and control over their lives and reporting feeling more connected to and supported by others.

The results, says Toth, point to the need for screening highrisk populations. None of these women were seeking treatment but were identified instead through a questionnaire and an interview at physicians’ offices and clinics for the Women, Infants, and Children subsidized nutrition program.

The research was published online in Development and Psychopathology.

Read more at www.rochester.edu/news.

Menstrual cycle influences concussion outcomes

How well a woman recovers from a concussion may depend on that time of the month.

Medical Center researchers found that women injured during the two weeks leading up to their period had a slower recovery and poorer health one month after injury compared to women injured during the two weeks directly after their period or women taking birth control pills.

The study was published in the Journal of Head Trauma Rehabilitation. If confirmed in subsequent research, the findings could alter the treatment for and prognosis of women who suffer head injuries from sports, falls, car accidents, or combat.

Several recent studies have confirmed what women and their physicians anecdotally have known for years: women experience greater cognitive decline, poorer reaction times, more headaches, extended periods of depression, longer hospital stays, and delayed return-to-work compared to men following head injury. Such results are particularly pronounced in women of childbearing age; girls who have not had their periods and post-menopausal women have outcomes similar to men.

“I don’t think doctors consider menstrual history when evaluating a patient after a concussion, but maybe we should,” says senior author Jeffrey Bazarian, associate professor of emergency medicine, who treats patients and conducts research on traumatic brain injury and long-term outcomes among athletes. “By taking into account the stage of their cycle at the time of injury we could better identify patients who might need more aggressive monitoring or treatment. It would also allow us to counsel women that they’re more-or-less likely to feel poorly because of their menstrual phase.”

Read more at www.urmc.rochester.edu/news.

The brain ‘takes out the trash’ while we sleep

neurons
Cerebral spinal fluid (in blue) enters the brain via a “plumbing system” that piggybacks on the brain’s blood vessels. A study led by Maiken Nedergaard, the Frank P. Smith Professor of Neurosurgery and codirector of the Center for Translational Neuromedicine, indicates that the brain is able to clear by-products of neural activity during sleep.

In findings that give fresh meaning to the old adage that a good night’s sleep clears the mind, a new study shows that a recently discovered system that flushes waste from the brain is primarily active during sleep. The revelation could transform scientists’ understanding of the biological purpose of sleep and point to new ways to treat neurological disorders.

“This study shows that the brain has different functional states when asleep and when awake,” says lead author Maiken Nedergaard, the Frank P. Smith Professor of Neurosurgery and codirector of the University’s Center for Translational Neuromedicine. “In fact, the restorative nature of sleep appears to be the result of the active clearance of the by-products of neural activity that accumulate during wakefulness.”

The study, which was published in the journal Science, reveals that the brain’s unique method of waste removal— dubbed the glymphatic system—is highly active during sleep, clearing away toxins responsible for Alzheimer’s disease and other neurological disorders. Furthermore, the researchers found that during sleep the brain’s cells reduce in size, allowing waste to be removed more effectively.

While recent findings have shown that sleep can help store and consolidate memories, the benefits do not appear to outweigh the accompanying vulnerability, leading scientists to speculate that there must be a more essential function to the sleep-wake cycle.

The new findings hinge on the discovery last year by Nedergaard and her colleagues of a previously unknown system of waste removal that is unique to the brain. The system responsible for disposing cellular waste in the rest of the body, the lymphatic system, does not extend to the brain. The brain maintains its own closed “ecosystem” and is protected by a complex system of molecular gateways— called the blood-brain barrier— that tightly control what enters and exits the brain. Read more and watch a video about the research at www.urmc.rochester.edu/news.

Study: Common Core influences classroom practices

girl at chalkboard

According to a study by researchers at the Warner School and several other institutions, a majority of middle school math teachers say the new Common Core math standards and teacher evaluations associated with the standards will ultimately drive their classroom practices.

These are among other findings released as part of a survey conducted by researchers from Rochester, Western Michigan University, Michigan State University, and Washington State University Tri-Cities in April and May 2013 that examines how teachers perceive the new standards, assessments, and the teacher evaluation process linked to the new standards.

“This is a challenging time for teachers, given the changes the Common Core standards represent for most states in terms of the mathematical content, the incorporation of the Common Core standards in state assessments, and the use of student test scores in teacher evaluations,” says Jeffrey Choppin, associate professor of mathematics education at the Warner School, who serves as the study’s principal investigator. “In order to better support and ease the transition for teachers—and their students— as schools continue to adopt and implement the new standards, it’s important that we understand the emerging issues and concerns related to the new standards.”

New York, along with 44 other states and the District of Columbia, adopted the standards, which were designed to focus on deepening students’ knowledge and ensuring that they are ready for college or employment by the time they graduate from high school. According to the funders and authors, the goal is to create consistency across the public education landscape. 

Read more at www.warner.rochester.edu/newsevents.

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