Science  14 Oct 2011:
Vol. 334, Issue 6053, pp. 162

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  1. Dark Ice on a Hot Planet


    Despite basking in the sun's fiery glow, tiny Mercury, the innermost planet in our solar system, is probably home to extensive ice fields. Twenty years ago, radar observations from Earth revealed small, highly reflective areas close to Mercury's poles, suggesting the presence of ice. Now, NASA's MESSENGER spacecraft, which has orbited Mercury since March, has confirmed that these radar-bright patches coincide with deep craters near the poles that never receive sunlight. This color-coded photo mosaic of Mercury's south polar region, presented 5 October at a joint meeting of the European Planetary Science Congress and the Division for Planetary Sciences of the American Astronomical Society, shows these “freezer” areas as dark blotches. According to MESSENGER instrument scientist Nancy Chabot of the Johns Hopkins University's Applied Physics Laboratory in Laurel, Maryland, one-fifth of the region within 200 kilometers of Mercury's south pole is in permanent shadow. “It's all consistent with there being water ice,” she says.

  2. Monkeys Control Virtual Limbs With Their Minds

    Brain-controlled prosthetics that enable a person to, say, pick up a pencil continue to improve for amputees, but limbs that can actually feel touch sensations have remained a challenge. Now researchers led by neuroscientist Miguel Nicolelis of Duke University in Durham, North Carolina, have created a virtual prosthetic arm that monkeys control using only their minds, and that enables them to feel virtual textures.

    To “close the loop” between controlling a limb and feeling physical touch, the researchers implanted two sets of tiny electrodes into a monkey's brain: one set in the motor control center, and the other in the part of the somatosensory cortex that processes the sensation of physical touch either from the left hand or the leg. Using the first set, the monkey could control a virtual monkey arm on a computer screen and sweep the hand over virtual disks with different “textures.” The second set of electrodes fed a series of electrical pulses (low frequency for rough texture, high frequency for fine texture) into the touch center of its brain. With little training, the monkeys could consistently distinguish the textures as if the arm was their own, the team reported 5 October in Nature.