What’s the News: When prions or amyloids make the news, it’s usually because they cause mad cow disease or Alzheimer’s—prions, after all, cause any proteins they touch to become as misfolded as they are, and amyloids, which are large clumps of wadded-together proteins, can jam the workings of cells.
But a new study in Cell suggests that a prion-like protein that forms amyloids has a normal, vital function in the brain. Far from being a memory destroyer, this protein, called CPEB, is necessary for long-term memory in fruit flies.
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New research suggests the mere act of walking through a doorway helps people forget, which could explain many millions of confusing moments that happen each day around the world. A study published recently in The Quarterly Journal of Experimental Psychology found that participants who walked through doorways in a virtual reality environment were significantly more likely to forget memories formed in another room, compared with those who traveled the same distance but crossed no thresholds.
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A 68-year-old concert cellist suffering from severe amnesia can still learn new music, researchers reported [pdf] at the Society for Neuroscience conference this weekend. In 2005, the cellist suffered a bout of herpes encephalitis, a dangerous infection that causes inflammation in the brain. His medial temporal lobes, brain structures important in remembering facts and events—what scientists call explicit memory—were destroyed. As a result, the cellist, referred to by the initials PM, was left with both retrograde amnesia (meaning he couldn’t remember events from his past) and anterograde amnesia (meaning he couldn’t form new memories).
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What’s the News: One of memory’s big jobs is to keep straight what actually happened versus what we imagined: whether we said something out loud or to ourselves, whether we locked the door behind us or just thought about locking the door. That ability, a new study found, is linked to the presence of a small fold in the front of the brain, which some people have and others don’t—a finding that could help researchers better understand not only healthy memory, but disorders like schizophrenia in which the line between the real and the imagined is blurred.
Scans of a brain with a distinctive paracingulate sulcus (left, marked by arrow) and without one (right)
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A twice-daily dose of insulin, sprayed deep in the nose for easy transit to the brain, may slow or stop the progression of Alzheimer’s disease, according to a new pilot study. The researchers gave 104 patients with mild to moderate Alzheimer’s disease or pre-Alzheimer’s cognitive impairment one of three nasal sprays for four months. One group of patients got a nasal spray with a moderate dose of insulin twice a day, one group got a higher dose, and the third got a squirt of saline solution, as a placebo. The memory, cognitive abilities, and day-to-day functioning of patients given insulin stayed constant or improved slightly—particularly for those given the moderate dose of insulin rather than the high dose—while the abilities and memory of patients given the placebo declined.
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What’s the News: Most of us need everyone to stop talking when we perform mental math. But for children trained to do math visually with a “mental abacus,” verbal disturbances roll off their backs, prompting psychologists to posit that unlike the rest of us, they aren’t routing their calculations through words.
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What’s the News: The left and right halves of the brain have separate stores for working memory, the information we actively keep in mind, suggests a study published online yesterday by the Proceedings of the National Academy of Sciences. People can, on average, hold only four pieces of information in working memory—say, where four strangers are seated in a room. The current study suggests that, in fact, working memory capacity is two plus two—two items stored in each side of the brain—rather than four items stored anywhere. This understanding could be used to design learning techniques and visual displays that maximize working memory capacity.
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What’s the News: Scientists have built a brain implant that can restore lost memories and reinforce new ones. The implant, tested in a recent study in rats, brings back a memory by recording and replaying the electrical activity of neurons in a part of the hippocampus, the brain’s long-term memory center. While the device is far from ready for use in humans, it’s an important step toward memory-boosting implants that could one day help patients who have developed dementia or suffered a stroke.
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Aplysia californica
What’s the News: Researchers have considerably weakened—and perhaps even erased—long-term memories in Aplysia, a type of marine slug, and in neurons in a lab dish, by blocking the activity of a particular enzyme. Understanding how to weaken and erase such memories could one day lead to new treatments for people suffering from post-traumatic stress disorder, who are haunted by memories of traumatic events.
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What’s the News: Scientists have for the first time directly linked freeway vehicle emissions with brain damage. Scientists used a new technique that involved trapping airborne toxins along Los Angeles’ 110 Freeway, freezing them in water, and exposing lab mice to the toxins. “As a society, we need to figure out ways to minimize the level of the very, very nasty particulates we are dumping into the air we breathe,” University of Southern California gerontology researcher Todd Morgan told the Los Angeles Times. “It’s having terrible consequences.” (more…)
A surprise to remember: Scientists have found that a naturally occurring hormone usually involved in cell repair is also present in the hippocampus of the brain, and when they extra doses of it to rats in their experiments, it appeared to greatly enhance the rats’ memory.
The hormone is called insulin-like growth factor II (IGF-II), and the fact that it showed up in the hippocampus (associated with memory and learning) made Cristina Alberini wonder if it could be a key player in memory formation. So she and her colleagues designed a test:
The team came up with a box that was lit on one side and unlit on the other. Rats that entered the dark side got a mild foot shock. The rats’ subsequent hesitation to return to the dark after getting shocked gave the scientists a measure of how well they remembered the traumatic event. [ScienceNOW]
The rats showed elevated IGF-II levels after the shock, but Alberini wanted to see whether tinkering with those levels could change the rats‘ ability to form and recall memories.
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Alzheimer’s: It’s a disease that afflicts over five million Americans, and there is currently no treatment for it. But researchers are getting closer to a diagnostic test for the disease. Last week a Food and Drug Administration (FDA) advisory committee recommended that the agency approve a brain scan that can detect the disease in a living patient.
The approval would be for a dye that homes in on plaque in the brain, making it visible on PET scans. Such scans would be especially valuable in a common and troubling situation — trying to make a diagnosis when it is not clear whether a patient’s memory problems are a result of Alzheimer’s disease or something else. If a scan shows no plaque, the problems are not caused by Alzheimer’s and could be from tiny strokes or other diseases. [New York Times]
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You’ve probably heard oxytocin referred to as the “love hormone,” but a new study in the Proceedings of the National Academy of Sciences reminds us that there’s much more to it than that. Jennifer Bartz and colleagues treated men either with nasal sprays that included oxytocin or placebo sprays that didn’t, with peculiar results.
From Ed Yong:
Before all of this, the men completed a series of widely used questionnaires to measure the state of their social ties. The questions assessed the nature of their bonds with their families and friends, how sensitive they are to rejection, how comfortable they are at being close to other people, how much they desire that closeness, and more. Shortly after using both sprays, the recruits also answered questions about their mother’s parenting style.
Bartz found that when she averaged out the volunteers’ results, the sniffs of oxytocin hadn’t seemed to colour their memories of their mothers. But things changed when she looked at them individually. Those who felt more anxious about their relationships took a dimmer view of their mother’s parenting styles when they sniffed oxytocin, compared to the placebo. Those who were more secure in their relationships reacted in the opposite way – they remembered mum as being closer and more caring when they took the oxytocin.
For the rest of this post, check out DISCOVER blog Not Exactly Rocket Science.
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Not Exactly Rocket Science: Can a sniff of oxytocin improve the social skills of autistic people?
80beats: The “Love Hormone” Oxytocin Helps People Recognize Faces They’ve Seen Before
DISCOVER: A Dose of Human Kindness, Now in Chemical Form examines oxytocin’s effects on generosity
Image: iStockphoto
A new drug seems to be able to reverse normal age-related memory decline in old mice–like a face-lift for neurons, bringing them back to their younger days. The results of the experimental treatment, which works by blocking certain stress hormones, were published in the Journal of Neuroscience.
“What’s most surprising is that even short-term inhibition was able to reverse memory loss in old mice,” says Jonathan Seckl, a professor of molecular medicine who was involved in the research. “I don’t think people had realized this was so reversible. It takes [the animals] back to being relatively young.” [Technology Review].
Research has shown that stress hormones called glucocorticoids play a role in memory loss, by damaging the brain over time. But targeting the glucocorticoids themselves is dangerous, because reducing their levels would leave the body without a stress response. The researchers therefore targeted an enzyme instead, which activates the hormone in neurons.
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California’s Proposition 19, a November ballot initiative to legalize marijuana, has fueled the ongoing fight over the drug’s health risks. While that battle has a month to go, a new study out in the British Journal of Psychiatry this backs up the idea that pot’s cognitive impairment is all about the makeup of the marijuana you’re smoking.
Valerie Curran and colleagues studied 134 volunteers as those volunteers smoked from their private stashes in their homes. The scientists had their subjects take a series of cognitive tests, both high and sober. They then took a small portion of the pot to the lab for analysis.
Curran found striking differences in the chemical compositions of different users’ marijuana, and those differences appeared to play a large role in how well the smokers performed on the tests while high.
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