News Scan Briefs; May 2005; Scientific American Magazine; by JR Minkel, Charles Q. Choi, W. Wayt Gibbs; 2 Page(s)

Mars seems to have a frozen lake on its surface, according to images obtained by the European Space Agency's Mars Express satellite. One hypothesis has it that Mars sporadically belches up volcanic gases and floodwater, leaving behind huge seas, which then evaporate. Researchers have identified the apparent remnants of such an outburst: a frozen body of water the size of Earth's North Sea. Although some experts dispute the finding, believing it to be lava flow, the formation is fragmented like ice on terrestrial seas. Crater counts indicate the object is roughly five million years old--young in geologic terms--and its horizontal surface, along with several craters that seem partially filled up, suggests that the ice remains to this day. The researchers posit that an eruption from two crevasses known as Cerberus Fossae provided the water, and a layer of volcanic ash settled on the resulting glacier, preventing its sublimation into vapor, they explain in the March 17 Nature.

So-called mirror neurons, discovered in monkeys, fire both when a person performs an action and when a person sees someone else perform the same action. These brain cells may be enabling us to understand the intention behind other people's behavior. To test the idea, investigators from the University of California at Los Angeles showed 23 volunteers three sets of video clips. The first depicts tea and cookies either arranged neatly or haphazardly: the context for an action. The second shows someone grasping a lone teacup: the action. The third shows someone grasping the teacup amid the other objects, implying the actor's intention of either having a sip of tea or cleaning the teacup. A specific group of mirror neurons in the right inferior frontal cortex was active only during the videos depicting intention, the researchers report online in the March PLoS Biology.