You may not be able to relive your youth, but part of your brain can. Scientists at Johns Hopkins university have found that newly made nerves in an adult brain’s learning centre go through a one-month phase when they are just as active as the nerves in a developing child. The study, published in the journal Neuron, suggests that new adult nerves have a more profound role than simply replacing dead ones.
Scientists traced the chemical signals received by newly made nerve cells in the adult mouse hippocampus by injecting virus particles to light up nerve progenitor cells.
Any freshly made nerves radiated green and became permanently marked for later detection.
When they looked at the brains of the mice, the researchers noticed that hippocampal nerves between one and two months old could radically increase or decrease the amount of signalling chemicals they received from neighbouring nerves. This capacity of nerves to adjust their chemical inputs is high in developing brains but becomes less strong in adults.
This heightened activity may explain how adults adapt to new experiences. The constant addition of new nerve cells may allow adults to incorporate fresh information without changing their brain circuitry.
Warning: smoking is sad for your health
The nicotine buzz that seems to lift your mood wears off more quickly than you might think.
A new study suggests that persistent smokers may have a higher risk of depression than people who’ve never smoked. The study, conducted by researchers at the University of Helsinki, also found that smokers who quit have an elevated risk of depressive symptoms in the short term.
Using data collected by the Finnish Adult Twin Cohort Project, researchers analysed the behaviour of about 9,000 smoking and non-smoking twins, whose health had been followed for 15 years. The results suggest that chronic smoking may have a role in the etiology of depression. However, while persistent chronic cigarette smoking predicts depressive symptoms, when adjusted for other factors associated with depression, the elevated risk of persistent smoking was only significant among men.
The study also found that smokers who quit had elevated depression risk in the short term, suggesting that those who return to cigarettes may be doing so to alleviate depressive symptoms. However, smokers who had quit successfully and remained abstinent through the follow-up did not have elevated depression risk.
Morgan Spurlock, star of Super Size Me...
Morgan Spurlock, star of Super Size Me, was not kidding. Scientists at Saint Louis University recently studied the effects on mice of a diet that was 40 per cent fat and abounding with high-fructose corn syrup, a sweetener common in fizzy drinks. The fat content is about the same you’d find in a typical McDonald’s meal, and the corn syrup translates to about eight cans of soda a day in a human diet. The mice were allowed only limited amount of physical activity.
Unlike other studies, the mice were not forced to eat; rather, they were able to dig in whenever they wanted - and dig in they did.
(The study indicated that fructose suppresses the feeling of fullness, unlike fibre-rich foods, which make you feel full quickly.)
The research, which lasted for 16 weeks, had dramatic results.
Dr Brent Tetri, who lead the project, says: ”We were surprised to find how severe the damage was and how quickly it occurred.
It took only four weeks for liver enzymes to increase and for glucose intolerance to begin.”
