Booster Shots

Oddities, musings and news from the health world

Category: brain

Rodent of the Week: Athletes! You must win at home

July 9, 2010 |  1:00 pm

Rodent_of_the_week There was good reason to be worried when the Lakers lost that second game of the NBA championship playoff series against Boston. The loss was at home. According to new animal research, winning at home appears to be important to the male species' ability to prepare for, and win, future conflicts.

In a study with mice, researchers showed that experiencing a win caused changes in the brains that enhanced the ability to win in the future. Researchers also found that winning at home had a particular effect, causing more activity in male hormone receptors in brain regions thought to influence social aggression.

The researchers paired territorial male mice who had winning experience -- sort of macho male mice that, by the way, are a species of California mice called Peromyscus californicus -- with smaller and sexually inexperienced male mice in various settings, such as home cages and neutral settings. Naturally, the mice fought. The researchers then examined the brains of the mice and compared them to similar mice that were not paired for fights. The mice that won both home and away victories had increased expression of hormone receptors in their brains. But only the brains of mice that won in their home cages showed increased hormone sensitivity in two areas of the brain thought to control motivation and reward. Mice that won at home also won more fights with larger and tougher mice when fighting in neutral locations.

The experience of winning, especially at home, appears to actually change the brains of mice. Perhaps this phenomenon extends to other species. In this somewhat dense conclusion, the authors wrote their results "are therefore provocative because they suggest a mechanism through which environmental context modulates socially induced changes to the functional properties of neural circuits that control behavioral motivation and reinforcement."

The study, released online Tuesday in the Proceedings of the National Academy of Sciences, was conducted by researchers at the University of Wisconsin.

-- Shari Roan

Photo credit: Advanced Cell Technology Inc.


Rodent of the Week: Why women are more vulnerable to psychiatric stress

June 18, 2010 |  5:13 pm

It’s well known that women are more susceptible to some kinds of psychiatric disorders than men. For instance, studies have found that depression and post-traumatic stress disorder are twice as common among women as among men. But why?

Rodent One theory involves a brain hormone called corticotropin-releasing factor, or CRF. It is responsible for kicking off the stress response, and it is regulated by the female sex hormone estrogen. So perhaps estrogen causes female and male brains to respond differently to CRF.

To test this, scientists at Children’s Hospital of Philadelphia and the nearby Thomas Jefferson University subjected male and female rats to a swim stress test. Then they studied their brains in minute detail.

It turned out that the female rats were more responsive to CRF – it registered more strongly in their brains than it did in the male rats. What’s more, the female rats weren’t able to tone down the hormone after their stressful swims. But the male rats were – their brain cells changed in a way that prevented some of the CRF from doing its usual job.

“The findings identify molecular and cellular mechanisms that could result in enhanced sensitivity of female rats to CRF and a decreased ability to adapt to excessive CRF,” the researchers wrote. But they cautioned that further research is needed to see if the same gender differences are at play in human brains.

The study was published this week in the June issue of Molecular Psychiatry.

-- Karen Kaplan

Photo: Advanced Cell Technology Inc.

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Rodent of the Week: How habits are formed

June 11, 2010 |  1:00 pm

Rodent_of_the_week When I was in high school, I had to drive a long distance on a freeway to get to school. After arriving, I often wondered how I got there. I didn't remember the drive or even thinking about driving.

This feeling is a common (and, yes, somewhat scary) experience that a group of neuroscientists think they can better explain. In an experiment with rats, researchers at MIT identified two distinct neural circuits in the brain that show distinct changes when the rats were learning to navigate a maze and, later, after they mastered the task.

The rats were placed in a maze that had chocolate sprinkles at the end. The activity in specific parts of their brains was analyzed as they learned the maze, which included a T-juncture where they had to stop and choose to turn right or left. The rats performed the maze repeatedly until they had learned it.

The study showed that one specific neural circuit became stronger with practice. A second neural circuit showed high activity occurring at times when the rats had to make a decision in the maze. But as they learned the maze, activity in this circuit declined. The task had become habitual.

So, arriving at school in one piece wasn't just a matter of luck. "It is good to know that we can train our brains to develop good habits and avoid bad ones," the lead author of the study, Ann Graybiel, said in a news release.

Understanding how specific regions of the brain change through learning could help in developing new treatments for brain-based diseases. The study was published Thursday in the journal Neuron.

-- Shari Roan

Photo credit: Advanced Cell Technology Inc.


Book Review: 'The Winner's Brain' by Jeff Brown and Mark Fenske with Liz Neporent

May 29, 2010 |  6:48 pm
Winner

Why are some people highly successful in life, while others just get by? Authors Jeff Brown and Mark Fenske say the difference between the high-achieving and the merely average is due not to IQs, life circumstances, financial resources, social connections or luck but to the workings of the brain. 

In "The Winner's Brain," Brown, a Harvard cognitive-behavioral psychologist, and Fenske, a neuroscientist, present evidence showing that the brains of the high-achieving operate differently from those of the average person. Brain scans measuring neutral activity show these processes at work, they say.

The good news, according to Brown and Fenske, is that the brain can be reshaped and rewired by employing the strategies successful people use to overcome obstacles and reach their goals. 

"The brain is active and subject to change no matter what you do -- this is one of the key discoveries of modern neuroscience," they write. "What sets the owner of a Winner's Brain apart is the desire and the know-how to take charge of the process."

Brown and Fenske say that transforming your thinking, emotions and behavior as well as the physical structure of your brain is not unlike doing bicep curls to reshape and add inches to your arms. 

The authors have identified five "brainpower tools" commonly used by successful people: seeing opportunity where others don't, accurately gauging and being willing to take risks, being able to stay focused on a goal, possessing the energy to take action and being able to accurately assess one's strengths and weaknesses.

Continue reading »

Gary Coleman death: What is an intracranial hemorrhage?

May 28, 2010 |  6:26 pm

Actor Gary Coleman died Friday of an intracranial hemorrhage after being taken off life support. According to the Associated Press, a statement from Utah Valley Regional Medical Center in Provo, where he was being treated, said that Coleman was lucid before becoming unconscious and being put on life support.

L35bwdnc Coleman battled health problems throughout his life, including a chronic kidney condition. A few months ago he suffered a seizure while on the set of a television show. Whether those things are related to his cause of death are as yet unknown.

An intracranial hemorrhage is a broad term that refers to any bleeding that occurs between the skull and brain due to a number of factors, said Dr. Keith Black, chairman and professor at the department of neurosurgery at Cedars-Sinai Medical Center in Los Angeles. A hemorrhage can be triggered by trauma to the head, or an aneurysm, the weakening of a vein or artery. The bleeding puts pressure on the brain, which in turn squeezes brain tissue or cuts down on blood supply to the brain.

"High blood pressure could also cause a hemorrhage, especially if blood pressure is not well controlled," Black said. "Also, a person could be at an increased risk of bleeding if their blood is not able to clot." Anti-clotting medications could exacerbate that, as could other health conditions.

There are three main types of bleeding that occur in an intracranial hemorrhages, said Black. A subdural bleed can be caused by a trauma to the head that tears veins and causes bleeding on the surface of the brain, in turn increasing pressure on brain tissue. An epidural hematoma is usually caused by a torn artery, again typically from trauma, but this type can cause more pressure on the brain. An intracerebral hemorrhage happens in the brain tissue itself when blood vessels rupture. That can be caused by high blood pressure, from a severe trauma, or when tangled arteries or blood vessels break.

Time is a hugely important factor in treating an intracranial hemorrhage, Black said. "Time is of the essence in getting to the hospital and getting the diagnosis correct," he said. "It's also important in understanding the underlying cause of the bleed so you can correct it and if possible, try to prevent it from getting worse and expanding."

Since high blood pressure is a possible cause of intracranial bleeding, even in young people, Smith said it's important to go for regular check-ups that include a blood pressure test.

--Jeannine Stein

Actor Gary Coleman died at the age of 42 from an intracranial hemorrhage. Photo credit: Kevin Winter / Getty Images



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