Physics Tip Sheet #67, May 29, 2007
American Physical Society
Highlights in this Issue: a living memory chip, black holes on the loose, and a clearer picture of ocean currents.
Learning, Memory, and Progress toward a Living Chip
Itay Baruchi and Eshel Ben-Jacob
A new experiment has shown that it's possible to store multiple rudimentary memories in an artificial culture of live neurons. The ability to record information in a manmade network of neurons is a step toward a cyborg-like integration of living material into memory chips. The advance also may help neurologists to understand how our brains learn and store information.
Itay Baruchi and Eshel Ben-Jacob of Tel-Aviv University used an array of electrodes to monitor the firing patterns in a network of linked neurons. As previous studies have shown, simply linking the neurons together leads them to spontaneously fire in coordinated patterns. In the study published this month in the journal Physical Review E the researchers found that they could deliberately create additional firing patterns that coexist with the spontaneous patterns. They claim that these new firing patterns essentially represent simple memories stored in the neuron network.
To create a new memory in the neurons, the researchers introduced minute amounts of a chemical stimulant into the culture at a selected location. The stimulant induced a second firing pattern, starting at that location. The new firing pattern in the culture along coexisted with the original pattern. Twenty-four hours later, they injected another round of stimulants at a new location, and a third firing pattern emerged. The three memory patterns persisted, without interfering with each other, for over forty hours.
In addition to producing the first chemically operated neuro-memory chip, the researchers propose that their work implies that chemical stimulation may be crucial to learning and memory formation in living organisms. -KM
Black Holes on the Loose
Manuela Campanelli, Carlos O. Lousto, Yosef Zlochower, and David Merritt
Two merging black holes can generate gravitational waves so powerful that the merged hole shoots out of its host galaxy at a speed of up to 2,500 miles per second, according to new simulations by two separate research groups. A pair of papers (Campanelli et al. and Gonzalez et al.) describing nearly identical examinations of the catastrophic events will be published back to back in an upcoming issue of Physical Review Letters.
A Clearer Picture of Ocean Currents
G. Froyland, K. Padberg, M. H. England, A. M. Treguier
A novel analysis of water flow in the Southern Ocean surrounding the Antarctic is revealing previously hidden structures that are crucial in controlling the transport of drifting plants and animals as well as the distribution of nutrients and pollutants that affect ocean life. Researchers at the University of New South Wales in Australia and the Universitat Paderborn in Germany discovered that barriers to currents, which can lead to swirling gyres and eddies that trap material for long periods, may escape detection with traditional analyses that concentrate on monitoring average water flow or sea surface height.
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