Tuesday, October 16, 2012

Our big brains may make us prone to cancer

Programmed cell death and cancer are intimately linked
There's a downside to everything. When humans evolved bigger brains, we became the smartest animal alive and were able to colonise the entire planet. But for our minds to expand, a new theory goes, our cells had to become less willing to commit suicide – and that may have made us more prone to cancer.

When cells become damaged or just aren't needed, they self-destruct in a process called apoptosis. In developing organisms, apoptosis is just as important as cell growth for generating organs and appendages – it helps "prune" structures to their final form.

By getting rid of malfunctioning cells, apoptosis also prevents cells from growing into tumours. "Reduced apoptotic function is well known to be associated with cancer onset," says John McDonald of the Georgia Institute of Technology in Atlanta.

McDonald compared skin cells from humans, chimpanzees and macaques and found that, compared to cells from other primates, our cells are reluctant to undergo apoptosis. When exposed to apoptosis-triggering chemicals, human cells responded significantly less than the chimp and macaque cells. Fewer human cells died, and they did not change shape in the ways cells do when preparing to die.

Down-regulated genes

In 2009, McDonald found that genes promoting apoptosis are down-regulated – essentially suppressed – in humans, and those turning it off are up-regulated (Medical Hypotheses, doi.org/bgkshp). Genes involved in apoptosis are also known to have changed rapidly during human evolution. The new study adds to the evidence that apoptosis is down-regulated in human cells.

"He has a sound experimental finding," says Todd Preuss of the Yerkes National Primate Research Center in Atlanta, Georgia. "What that means in the broader context is open to debate."

McDonald suggests that humans' reduced capacity for apoptosis could help explain why our brains are so much bigger, relative to body size, than those of chimpanzees and other animals. When a baby animal starts developing, it quickly grows a great many neurons, and then trims some of them back. Beyond a certain point, no new brain cells are created.

Human fetuses may prune less than other animals, allowing their brains to swell. "Natural selection for reduced apoptotic function only makes sense with respect to an increase in brain size," McDonald says. Proteins called executioner caspases are involved in apoptosis, and if these are turned off in mice, the animals grow enormous brains.

Skin cells are not neurons, cautions James Noonan of Yale University. "It remains to be seen whether this happens in the developing brain." Noonan says the idea shouldn't be dismissed, but he wants to see much more evidence.

Bigger brains, longer lives

Preuss says that lower levels of apoptosis could also help explain why humans live so much longer than other primates, something that allows us to lavish time on raising children and acquiring knowledge. "Animals with larger brains tend to live longer," he says.

"The connection with cancer is really intriguing," Preuss adds. There isn't systematic data on cancer rates in non-human primates, but apes with tumours are rare. That suggests we might need to be careful about using animal models to study cancer. "Humans have modified our biology in ways people haven't taken into account," he says.

Technology can alter brain structure in kids: Experts

Digital revolution can cause structural changes in brains of children and trigger mental health problems in adults, experts have warned.
Technology can alter brain structure in kids: Experts
MELBOURNE: Digital revolution can cause structural changes in brains of children and trigger mental health problems in adults, experts have warned.

Scientists are starting to worry that technology while transforming the way we live is also making people ill, The Age reported.

"I see kids clinically who spend the whole day engaged with electronic media and it's clearly a problem," said Professor George Patton from the Royal Children's Hospital's Centre for Adolescent Health.

"During those teenage years when the brain is in a very active phase of development and learning to process information about relationships and emotions, there's a concern that these kids are actually going to be wired differently in the future, given the malleability of brains at that age," Patton was quoted as saying by the paper.

"They may grow accustomed to, and be more comfortable with, the kinds of relationships that happen in this electronic space," Patton said.

Medical opinion is divided on whether technology will irreparably rewire brains to crave instant gratification and screen-based stimulation.

Some experts believe there is already clinical evidence that behaviours such as online multitasking or addiction to Facebook 'likes' bear the hallmarks of medical conditions such as hyperactivity and obsessive compulsive disorder.

Larry Rosen, a Californian psychologist and one of the world's leading authorities on technology overuse, believes future generations will increasingly suffer from "iDisorders" - psychiatric conditions such as narcissistic personality disorder, mania and attention deficit disorder, sparked by excessive use of social media, smartphones and computers.

He said the consequences of living life through a screen are already being seen in heavy users, who have diminished attention spans, impaired learning and difficulty forming relationships in the real world.

New Research Reveals Complexity of Brain’s Auditory Processing

A new study links motor skills to perception, enhancing the findings of earlier brain imaging techniques that merely hinted at this link.
Auditory testing

The Gist

Questioning the sound of one hand clapping may be an ancient Asian riddle to inspire Zen Buddhists, but it turns out that exactly what we hear may depend on what our hands are doing. That’s right—depending on whether your right or left hand is actively engaged in activity while listening could ultimately change how your brain processes the sounds you hear.

New research published this week and presented at Neuroscience 2012, the annual meeting of the Society for Neuroscience, is among the first to match human behavior with the brain’s specific left brain/right brain auditory tasks. Earlier brain imaging tests also observed specialization of auditory processing in the brain’s left and right hemispheres based on the tone and speed of speech as it was heard.

The new findings, as reported by senior researcher Dr. Peter E. Turkeltaub, M.D., Ph.D., a neurologist in the Center for Brain Plasticity and Recovery at Georgetown University in Washington, D.C., may suggest new methods to help speech pathologists assist patients who have barriers to speaking after suffering a stroke. Aphasia, the medical term for the disorder, affects more than one million Americans according to the Aphasia Hope Foundation, a nonprofit that raises awareness about the condition.

The Expert Take

According to Turkeltaub, the first challenge is to more fully understand the basic organization of the brain’s auditory systems.

“Understanding better the specific roles of the two hemispheres in auditory processing will be a big step in that direction,” he says in the study. “If we find that people with aphasia, who typically have injuries to the left hemisphere, have difficulty recognizing speech because of problems with low-level auditory perception of rapidly changing sounds, maybe training the specific auditory processing deficits will improve their ability to recognize speech.”

In an exclusive interview with Healthline, Turkeltaub elaborates, “The first step will be finding out whether speech comprehension problems in people with stroke occur in part due to problems in processing rapidly changing sounds, like the ones we used in this study. If that’s true, then this study suggests that asking people with stroke to attempt movement of the right hand during speech comprehension therapy might improve outcomes.”  

Source and Method

Turkeltaub and his team embedded rapidly and slowly changing sounds in background noise and asked 24 volunteers to indicate whether they heard the noises by pressing a button. Volunteers were also asked to switch from depressing the button from their right to their left hand every 20 seconds. When test subjects used their right hands, they heard more rapidly changing sounds more often. The opposite was found to be true for the left hands and the dominance of more slowly changing sounds.

“Since the left hemisphere controls the right hand and vice versa, the results demonstrate that the two hemispheres specialize in [hearing] different kinds of sounds—the left hemisphere likes rapidly changing sounds, such as consonants, and the right hemisphere likes slowly changing sounds, such as syllables or intonation,” explains Turkeltaub. “These results also demonstrate the interaction between motor skills and perception. Imagine that you’re waving an American flag while listening to one of the presidential candidates. The speech will actually sound slightly different to you depending on whether that flag is in your left or right hand.”

As of now, only right-handed people have taken part in the research.    

Other Research

While the human brain remains among the last medical frontiers in terms of our ability to understand its complex system of processes, researchers and clinicians are growing ever closer to understanding its elegance.
For instance, brain mapping—making determinations about the areas of the brain that become activated when performing various tasks—has been ongoing since the 1990s.

In 2001, a University of Alabama study examined and mapped via magnetic resonance imaging (MRI) the areas of the brain that became engaged when listening to actual words versus pseudo-words or nonsense. In that study, brains listening to pseudo-words demonstrated significantly increased brain activity.

More recently, a 2012 study observed the brain function in monkeys undergoing MRI tests. That research showcased distinct differences in right and left brain dominance depending on whether the animals heard species-specific vocalizations, human speech, scrambled versions of both, or complete silence.      

The Takeaway

Even though Turkeltaub claims the effects observed in the 2012 Georgetown University study were minimal, they could very well lead to significant improvements in patients struggling to understand language following a stroke. Other patients challenged by speech problems, such as children with dyslexia, may also eventually benefit from the findings.

“The effects we observed on perception here were relatively small,” explains Dr. Turkeltaub, “but even a small beneficial effect on each day of [speech] therapy might accumulate over time, amplifying the long-term benefit of that therapy in a clinically meaningful way.”

Books, toys may affect children's brain structure: study

BEIJING, Oct. 16 (Xinhuanet) -- Books and educational toys introduced to children at very early stage of life may predict the structure of their brains later in life, a new study finds.

The finding was presented Monday in the Society for Neuroscience's annual conference in New Orleans, the United States.

By following 64 people for more than 20 years from their age of four, researchers from University of Pennsylvania find the children who had access to books and educational toys had better development of their brains.

The effect was particularly noticeable in a region called lateral left temporal cortex, which plays a key role in language and thought.

"The time we spend with our parents before we are in school is going to affect us probably for the rest of our lives," said Brian Avants, the study’s lead author and an assistant professor of radiology at University of Pennsylvania.

The study also proved the stimulations at age of eight was no longer effective on brain development as it was at age of four.

"These findings underscore the human brain's sensitivity to its early environment. They provide powerful evidence that even relatively minor variations within the normal range of home experience can affect brain development over a lifetime," he noted.

Brain Scientists Uncover New Links Between Stress And Depression

Scientists say they're learning more about how to keep stress from damaging mental health.
Scientists say they're learning more about how to keep stress from damaging mental health.

Even extreme stress doesn't have to get you down.

That's the message from brain scientists studying the relationship between stress and problems such as depression, anxiety and post traumatic stress disorder, or PTSD.

Researchers at the Society for Neuroscience meeting in New Orleans presented studies showing how stress caused by everything from battlefield trauma to bullying can alter brain circuitry in ways that have long-term effects on mental health.

Current treatments for these problems often come up short. But the scientists say new insights about how stress affects the brain suggest several ways the process could be interrupted or reversed.
  "That's the holy grail and we're moving in that direction," says Dipesh Chaudhury of the Mount Sinai School of Medicine in New York.

Chaudhury says one way traumatic events appear to cause depression is by inhibiting the brain's so-called reward system, which normally causes pleasurable feelings when we spend time with friends or eat a favorite food. Soldiers with PTSD and people with major depression often report that these things no longer give them pleasure.

Mice respond in a similar way to traumatic events, Chaudhury says. And his research shows that this response can be prevented by reducing the activity of certain brain cells involved in the reward system.
The trick now is to find a drug that produces the same effect in people, Chaudhury says.

Another way stress affects mental health is by releasing chemicals that impair the function of the prefrontal cortex, which is where higher level thought takes place, says Amy Arnsten, a neurobiologist at Yale. When that happens, she says, "We switch from being thoughtful creatures to being reactive creatures."

That can lead to anxiety and PTSD, Arnsten says. But studies suggest at least two drugs seem to help the prefrontal cortex work better.

One of these is the blood pressure drug Prazosin, which has been used experimentally to treat both soldiers and civilians with PTSD. Another is a drug called guanfacine, which seems to help drug addicts who relapse under stress.

The anesthetic and anti-depressant drug ketamine also seems to help with PTSD, says Neil Fournier, a researcher at Yale University School of Medicine.

Studies in mice show that ketamine helps them forget fearful events, probably because it causes the formation of new nerve connections in the brain. And there is preliminary evidence that wounded soldiers who got ketamine to relieve pain were less likely to develop PTSD.

Early years key to brain development

AN early childhood surrounded by books and educational toys will leave positive fingerprints on a person’s brain well into their late teens, a 20-year research study has shown.
Scientists found that the more mental stimulation a child gets around the age of four, the more developed the parts of their brains dedicated to language and cognition will be in the decades ahead.

It is known that childhood experience influences brain development but the only evidence scientists have had for this has usually come from extreme cases such as children who had been abused or suffered trauma.
Martha Farah, director of the centre for neuroscience and society at the University of Pennsylvania, who led the latest study, wanted to find out how a normal range of experiences in childhood might influence brain development.

Farah took data from surveys of home life and brain scans of 64 participants over 20 years. Her results, presented Saturday night at the annual meeting of the Society for Neuroscience in New Orleans, showed that cognitive stimulation from parents at the age of four was the key factor in predicting the development of several parts of the cortex — the layer of grey matter on the outside of the brain — 15 years later.

The participants had been tracked since they were four years old. Researchers had visited their homes and recorded details about their lives to measure cognitive stimulation, such as the number of children’s books they had, whether they had toys that taught them about colours, numbers or letters, or whether they played with real or toy musical instruments.

The researchers also scored the participants on “parental nurturance” — how much warmth, support or care the child got from the parent. The researchers carried out the same surveys when the children were eight years old. When the participants were between 17 and 19, they had their brains scanned.

Farah’s results showed that the development of the cortex in late teens was closely correlated with a child’s cognitive stimulation at the age of four. All other factors — including parental nurturance at all ages and cognitive stimulation at age eight — had no effect.

Farah said her results were evidence for the existence of a sensitive period, early in a person’s life, that determined the optimal development of the cortex. “It really does support the idea that those early years are especially influential.”

Andrea Danese, a clinical lecturer in child and adolescent psychiatry at the Institute of Psychiatry, King’s College London, said: “Parents may not be around when their teenage children are faced with important choices about choosing peers, experimenting with drugs, engaging in sexual relationships, or staying in education.

“Yet, parents can lay the foundations for their teenage children to take good decisions, for example by promoting their ability to retain and elaborate information, or to balance the desire for immediate reward with the one for greater, long-term goals since a young age.”

Your brain can make you fat

Your brain can make you fat

Some people’s brains unable to process hormone that regulates appetite, leading to weight gain. Discovery paves way for targeted obesity drugs.

We are constantly told it’s a consequence of eating too much and not moving enough.

But scientists believe our brains could also be making us fat.

In a new study, researchers from the University of Michigan suggest some of us have brains that are wired differently, meaning they don’t respond to one of the hormones that regulates appetite.

There are two key hormones related to our weight, the first being grehlin. Released by the stomach to increase hunger, it also slows the metabolism and decreases the body’s ability to burn fat.

The second, and the one the study focused on, is leptin. This plays a key role in regulating body weight by signalling to the brain to reduce appetite and burn more calories. As a result, it has a significant link to obesity. Previous research has found that people who don’t have leptin are more likely to have problems with their weight. Or, that some people produce very high levels of it which ‘overloads’ the receptor in the brain that deals with it. This impairs the very mechanism that should eliminate excess fat. Now the researchers at the University of Michigan have discovered why the brain receptor responsible for processing leptin may not work.

They found that the receptor has two ‘legs’ that swivel until they encounter leptin in the brain. One possibility is that the receptors of people who are overweight may be lacking these ‘legs’, so the leptin cannot bind to the brain receptor.

The study is published online in the journal Molecular Cell. The discovery could lead to targeted treatments for obesity and other hormone-related diseases.

‘This study may help solve an important issue we’ve been struggling with for some time,’ said Alan Saltiel, director of the Life Sciences Institute at the university.

‘Since leptin is a master regulator of appetite, understanding why resistance to its effects develops in obesity has been a major obstacle to discovering new drugs for obesity and diabetes. ‘Developing a clear picture of how leptin can bind to its receptor may be the first step in overcoming leptin resistance.’