Sci News AugustBy Thomas McKinnon 5 August 2009 | Categories: news
Practice makes perfect
Practice makes perfect when it comes to learning intricate muscle movements. Now scientists know why. According to a recent report in the journal Proceedings of the National Academy of Sciences, two brain pathways help muscles remember their steps. One is a dynamic storage facility that can be overwritten while learning the muscle action; the other permanently stores the information for easy access when the action needs to be repeated. While young zebra finches were learning to sing, scientists played white noise every time the bird sang a specific section at a lower pitch than usual. Over several training hours, the bird gradually raised the pitch of the specific section of its song. Temporary inactivation of the dynamic memory pathway made a bird immediately revert to the pitch sung before training. However, after 24 hours newly learnt song patterns had been transferred to the permanent storage pathway, and could later be reproduced. ‘Continued education’, indeed.
Stars and stripes
Astronomers announced in the Astrophysical Journal that they may be a step closer to understanding a star’s life – by studying its death. As a star prepares for demise, it sheds some of its outer material to form a surrounding dust and gas cloud. Loss of the outer material gradually exposes the star’s inner core, which illuminates the starry remnants. This is known as a nebula. A new image of the Helix Nebula, surrounding one of the closest dying stars to Earth, revealed thousands of bright comet-shaped gas-and-dust knots – almost like a celestial fireworks display. Hydrogen steadily evaporates from these gas knots. Strong solar winds blowing from the core then causes the illuminated hydrogen gas to form streaky flashes trailing behind the knots. The scientists think that these knots may be good places to look for what star leftovers really look like.
A recent study published in the journal Current Biology, confirmed that house cats rule their human orderlies quite efficiently – by voice alone. Researchers recorded the sounds cats make around meal times, and then asked listeners to rate the pleasantness and urgency of the calls. Meal time meows were rated consistently to sound less pleasant and more urgent than other cat sounds, even by listeners who were not cat owners. Analysis showed that an annoying meow is cunningly disguised in a pleasant-sounding purr. When the recorded sounds were re-synthesised without the wailing meow, the calls were rated as significantly less urgent. It seems thus that the meal time sound presents just the right meow-purr combination to signal a vulnerability that’s hard to ignore. The result? A speedy refilling of Felix’s food bowl.
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