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FROM THE NEW ZCIENTIST

A fat tummy shrivels your brain


HAVING a larger waistline may shrink your brain.

Obesity is linked to an increased risk of type 2 diabetes, which is known to be associated with cognitive impairment. So Antonio Convit at the New York University School of Medicine wanted to see what impact obesity had on the physical structure of the brain. He used magnetic resonance imaging to compare the brains of 44 obese individuals with those of 19 lean people of similar age and background.

He found that obese individuals had more water in the amygdala - a part of the brain involved in eating behaviour. He also saw smaller orbitofrontal cortices in obese individuals, important for impulse control and also involved in feeding behaviour (Brain Research, in press). "It could mean that there are less neurons, or that those neurons are shrunken," says Convit.

Eric Stice at Oregon Research Institute, Eugene, thinks that the findings strengthen the "slippery slope" theory of obesity. "If you overeat, it appears to result in neural changes that increase the risk for future overeating," he says. Obesity is associated with a constant, low-level inflammation, which Convit thinks explains the change in brain size.

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Imagine running with open arms into the arms of the murderous elites who want to kill you. Even though we do that anyway, its now officially foolproof.
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An Injection Straight to the Brain Makes Rats Forget Their Fears

From popular science (shills)

Just about everyone can think of some memory he or she would rather forget. For some, it's something like a relationship gone wrong, or high school. For others -- like soldiers returning from war zones -- those bad memories can be highly disruptive, impeding the ability to live a normal life. But Puerto Rican researchers may have found a way to reduce the fear associated with our memories by injecting a naturally occurring chemical directly into the brain, replacing anxiety with feelings of security.

This isn't the stuff of sci-fi; the procedure doesn't pave over miserable memories with better, different ones. It works by chemically mimicking what's known in the lab as extinction learning. For instance: Researchers can instill a learned fear in lab rats in a Pavlovian fashion, sounding a certain tone while applying a light shock to the rats. After a while, rats learn to fear the pain associated with the chime. Researchers can undo this process via extinction learning, which is the exact opposite; sound the chime but don't present the shock. Do this enough times and rats can unlearn that fear.

Related ArticlesScientists Use Precise Flashes of Light to Implant False Memories in Fly BrainsFor the First Time, Scientists Photograph Memories Being Formed Modeling MemoriesTagsScience, Clay Dillow, anxiety, biology, fear, neurology, neuroscience, ptsdResearchers at the University of Puerto Rico set their experiment up around just such a model, but they wanted to extinguish the fear chemically, rather than through repetitive learning. To do so, they injected a naturally occurring chemical known as brain-derived neurotrophic factor (BDNF) into the rats' infralimbic prefrontal cortexes. BDNF is involved in several types of learning, including extinction learning. The researchers hoped that by artificially upping the amount present in the prefrontal cortex they could coax the rats into unlearning their fear of the chime. In experiments, rats were conditioned to fear the chime via electric shock until they would consistently freeze up each time the chime sounded. The next day, rather than undergoing extinction learning, the variable group was injected with BDNF. The control rats were left untouched. The next day, researchers began sounding the chime. The control rats seized up as expected, fearful of the shock. The variable rats did not. Further testing showed that the BDNF experiment very closely mirrored genuine extinction training.

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