Neuroscientists have unlocked the secret behind alcohol-induced amnesia, otherwise known as a “blackout,” which can last anywhere from a few minutes to several hours.

According to researchers at Washington University School of Medicine in St. Louis, consuming large amounts of alcohol does not necessarily destroy brain cells as once believed.

Instead, alcohol interferes with certain receptors in the brain, which then produce steroids that hinder long-term potentiation (LTP), a process that strengthens neuron connections and is critical for learning and memory.

“The mechanism involves NMDA receptors that transmit glutamate, which carries signals between neurons,” says Yukitoshi Izumi, MD, PhD, research professor of psychiatry at Washington University School of Medicine in St. Louis.

“An NMDA receptor is like a double-edged sword because too much activity and too little can be toxic. We’ve found that exposure to alcohol inhibits some receptors and later activates others, causing neurons to manufacture steroids that inhibit LTP and memory formation.”

Izumi notes that the different receptors involved in this process interfere with synaptic plasticity in the hippocampus — a region of the brain important in cognitive function.

Izumi and first author Kazuhiro Tokuda, MD, research instructor of psychiatry, treated rat hippocampal cells with moderate amounts of alcohol and found that LTP was not affected; however, exposing the cells to large amounts of alcohol inhibited the memory formation mechanism.

“It takes a lot of alcohol to block LTP and memory,” says senior investigator Charles F. Zorumski, MD, the Samuel B. Guze Professor and head of the Department of Psychiatry.

“But the mechanism isn’t straightforward. The alcohol triggers these receptors to behave in seemingly contradictory ways, and that’s what actually blocks the neural signals that create memories. It also may explain why individuals who get highly intoxicated don’t remember what they did the night before.”

Not all NMDA receptors are blocked by alcohol — instead, their activity is cut approximately in half.

“The exposure to alcohol blocks some NMDA receptors and activates others, which then trigger the neuron to manufacture these steroids,” Zorumski says.

The researchers emphasize that alcohol doesn’t trigger blackouts by killing neurons. Instead, the steroids interfere with synaptic plasticity to hinder LTP and memory formation.

“Alcohol isn’t damaging the cells in any way that we can detect,” Zorumski says. “As a matter of fact, even at the high levels we used here, we don’t see any changes in how the brain cells communicate. You still process information. You’re not anesthetized. You haven’t passed out. But you’re not forming new memories.”

Memory formation is also blocked through the consumption of other drugs. When combined, alcohol and certain other drugs are far more likely to trigger blackouts than either substance alone.

The scientists discovered that certain drugs, called 5-alpha-reductase inhibitors, block the manufacturing of steroids and in turn preserve LTP in the rat hippocampus. These include the drugs finasteride and dutasteride, which are often prescribed to reduce an enlarged prostate gland. In the brain, however, those substances seem to sustain memory.

The team plans to study 5-alpha-reductase inhibitors to determine whether these drugs, and similar substances, may be able to play a role in preserving memory.

The study is published in The Journal of Neuroscience.

Source:   Washington University School of Medicine

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Laboratory research suggests long-term exposure to air pollution can lead to learning and memory problems and even depression.

Ohio State researchers discovered that the long-term effects of breathing polluted air can cause changes in the brain as well as damage to the heart and lungs.

“The results suggest prolonged exposure to polluted air can have visible, negative effects on the brain, which can lead to a variety of health problems,” said Laura Fonken, lead author of the study and a doctoral student in neuroscience.

“This could have important and troubling implications for people who live and work in polluted urban areas around the world.”

The study appears online this week in the journal Molecular Psychiatry.

In previous studies in mice, researchers found that fine air particulate matter causes widespread inflammation in the body, and can be linked to high blood pressure, diabetes and obesity.

This new study aimed to extend their research on air pollution to the brain.

“The more we learn about the health effects of prolonged exposure to air pollution, the more reasons there are to be concerned,” said Randy Nelson, co-author of the study. “This study adds more evidence of pollution’s negative effects on health.”

In the new study, mice were exposed to either filtered air or polluted air for six hours a day, five days a week for 10 months – nearly half the lifespan of the mice.

The polluted air contained fine particulate matter, the kind of pollution created by cars, factories and natural dust. The fine particulates are tiny – about 2.5 micrometers in diameter, or about 1/30th of the average width of a human hair. These particles can reach deep areas of the lungs and other organs of the body.

The concentration of particulate matter that the mice were exposed to was equivalent to what people may be exposed to in some polluted urban areas, according to the researchers.

After 10 months of exposure to the polluted or filtered air, the researchers performed a variety of behavioral tests on the animals.

In a learning and memory test, mice who breathed the polluted air took longer to learn essential behaviors related to survival and were less likely to remember key behaviors.

In another experiment, mice exposed to the polluted air showed more depressive-like behaviors (such as anxiety) than did the mice that breathed the filtered air.

In an effort to determine how air pollution can lead to these changes in learning, memory and mood researchers tested the hippocampal area of the mice brains.

“We wanted to look carefully at the hippocampus because it is associated with learning, memory and depression,” said Fonken.

Results showed clear physical differences in the hippocampi of the mice who were exposed to polluted air compared to those who weren’t.

The researchers looked specifically at branches that grow off of nerve cells (or neurons) called dendrites. The dendrites have small projections growing off them called spines, which transmit signals from one neuron to another.

Mice exposed to polluted air had fewer spines in parts of the hippocampus, shorter dendrites and overall reduced cell complexity.

“Previous research has shown that these types of changes are linked to decreased learning and memory abilities,” said Nelson.

In other studies, several of the co-authors of this study found that chronic exposure to polluted air leads to widespread inflammation in the body, which is linked to a variety of health problems in humans, including depression.

Again, researchers found evidence that the low-grade inflammation was evident in the hippocampus.

In mice that breathed the polluted air, chemical messengers that cause inflammation – called pro-inflammatory cytokines – were more active in the hippocampus than they were in mice who breathed the filtered air.

“The hippocampus is particularly sensitive to damage caused by inflammation,” Fonken said. “We suspect that the systemic inflammation caused by breathing polluted air is being communicated to the central nervous system.”

Source: Ohio State University

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Gamblers with the highest levels of impulsivity appear to be more prone to errors in reasoning associated with gambling, such as superstitious behaviors (carrying a lucky charm) and blaming losses on poor luck or “cold” machines, according to a new study led by the University of Cambridge.

Researchers from Cambridge and Imperial College London observed and compared 30 compulsive gamblers who were seeking treatment at the National Problem Gambling Clinic with 30 non-gamblers from the general population.

“The link between impulsivity and gambling beliefs suggests to us that high impulsivity can predispose a range of more complex distortions — such as superstitions — that gamblers often experience. Our research helps fuse these two likely underlying causes of problem gambling, shedding light on why some people are prone to becoming pathological gamblers,” said researcher Luke Clark, Ph.D.

To test impulsivity, researchers asked participants several questions about trade-offs between smaller amounts of money available immediately versus larger amounts of money in the future.  The gamblers were far more likely to choose the immediate money even though it was a smaller amount.  (Psychologists define impulsivity as a preference for the immediate smaller rewards on this task.)

It was also found that gamblers were especially impulsive during high or low moods,  considered factors that can trigger gambling sprees.

Similar to treatment-seeking gamblers elsewhere in the world, the group from the National Problem Gambling Clinic was mostly male, and experienced a moderate rate of other mental health issues including alcohol abuse and depression.

“There are promising developments in treatments for problem gambling such as psychological therapies and drug medications. We hope that our research will provide additional insight into the problem and inform future treatments,” said Clark.

The research was funded by the Medical Research Council and is published in the journal Psychological Medicine.

Source:  University of Cambridge

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Emerging research suggests nicotine receptors play an important role in social interaction and the ability to choose between competing motivations.

In the new research, scientists from France show that the nicotinic receptors in the prefrontal cortex are essential for social interaction in mice and that this area of the brain is necessary for adapted and balanced social interactions to occur.

Experts believe this this new knowledge could eventually lead to new treatments for ADHD, schizophrenia, and depression, among other illnesses.

To make this discovery, Sylvie Granon and colleagues introduced mice into an open space and tested their will to interact with other mice of the same sex or to explore a novel place.
The respective times spent for either social contact or novelty exploration were measured and quantitatively evaluated.

Researchers then removed the prefrontal cortex in otherwise normal mice, which resulted in mice with significant social deficits. Those genetically modified to lack the nicotinic receptor gene for a widespread subunit called beta2 subtype, seemed to favor social contact rather than the investigation of a novel environment.

When the beta2 nicotinic receptor in the brain was re-expressed, a normal balance between social contact and novelty seeking was restored.

Researchers say the findings show that there is a biological explanation for social interaction.

“This research can be summed up by saying that it’s the real-life equivalent of Chatty Cathy marrying the Marlboro Man,” said Gerald Weissmann, M.D., Editor-in-Chief of the FASEB Journal.

“Who could have guessed that there may be a biological explanation for ‘social butterflies.’ The explanation was found in an area of the brain that for decades has been considered a locus for nicotine addiction.”

Source: Federation of American Societies for Experimental Biology

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A new study suggests cell phone communication between a parent and their teenager can affect the quality of their relationship.

Researchers believe the details of the conversation, the purpose and tone of the conversation and who initiated the call are important factors for improving the parent-child bond.

The study is reported online in the peer-reviewed journal Cyberpsychology, Behavior, and Social Networking.

Study author Robert Weisskirch, M.S.W., Ph.D., notes that parents can use a cell phone to extend their parenting reach in a non-invasive manner. For example, parents can monitor an adolescent’s whereabouts and activities, track their schoolwork, offer support, voice disapproval or criticism, or discipline their teen.

Similarly, adolescents may use their cell phones to communicate positive or negative feelings or information with their parents.

In the current study, Weisskirch expands on how the frequency, nature, and content of parent-adolescent cell phone calls relate to the quality of the parent-child relationship.

In the review, concepts such as self-esteem, perceptions of family conflict, and family dynamics — including closeness and support –are reviewed in the context of a cellular connection.

Source: Mary Ann Liebert

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