Random Samples

Science  15 Aug 2008:
Vol. 321, Issue 5891, pp. 895

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    Deep brain stimulation (DBS) is looking ever more promising for people with persistent severe depression that resists drugs, therapy, and shock treatments.

    A team at the University of Toronto in Canada and Emory University in Atlanta, Georgia, has treated 20 patients for a year or more with DBS—a technique also tried for Parkinson's disease and severe obsessive-compulsive disorder. The researchers, led by Toronto neurosurgeon Andres Lozano, targeted an area called the sub-callosal cingulate gyrus, which brain imaging has shown to be hyperactive in severe depression. They surgically inserted electrodes into each side of a patient's brain, ran wires under the skin down the neck, and attached them to a low-voltage pulse generator embedded under a collarbone. Patients then came in regularly for monitoring and tune-ups. Sixty percent of them improved significantly, and about one-third achieved remission.

    Skull x-ray shows electrodes deep in brain. CREDIT: HELEN MAYBERG/EMORY UNIVERSITY

    Psychiatrist Helen Mayberg, a co-author, says it's still unclear why DBS works. It may stimulate some neurocircuitry, stop abnormal firing in other circuits, or cause the release of neurotransmitters affected by antidepressants, the team reported online last month in Biological Psychiatry.

    “The results are encouraging,” says Wayne Goodman, a psychiatrist at the National Institute of Mental Health in Bethesda, Maryland. But DBS is still brain surgery, so it's a last resort.


    “Between the opposition and lack of funding, it's been a battle to survive for the last 10 years. … This is at least the sixth time we've had the telephones turned off.”

    —Robert Lanza, chief scientist at Advanced Cell Technology, pioneering company in research on human embryonic stem cells that has been reported to be in a financial crisis.



    How do ants avoid gridlock when their trails narrow into one-way paths? Vincent Fourcassié, a biologist at Paul Sabatier University in Toulouse, France, decided the question needed answering, so he and colleagues set up experiments in which ants had to cross a narrow bridge to get from nest to foraging site and back.

    It turned out that different species follow different rules to determine who goes first. The black garden ant, Lasius niger, which feeds on sugary excretions from aphids, won't enter the bridge if another ant is crossing from the opposite direction. In contrast, the leaf-cutter ant, Atta colombica, which farms fungi for food on beds of shredded leaves, will make way for ants carrying leaves back to the colony. Fourcassié reported the results last month at the European Conference on Behavioural Biology in Dijon, France.

    Guy Théraulaz, a biologist at Paul Sabatier University who studies traffic in animals and humans, says this kind of research shows how simple algorithms followed by individuals lead to complex behaviors—in this case, smoothly flowing two-way traffic on a single-lane track.


    Yesterday, all your troubles seemed so far away. But what about your memories? Scientists in the United Kingdom are launching the Magical Memory Tour, a study that uses people's recollections of the Beatles as a lens to look at what they have retained about their lives.

    The project, an online survey devised by psychologists Martin Conway and Catriona Morrison at the University of Leeds, U.K., asks people to describe the first memory that comes to mind related to the Fab Four—such as a movie, a news item, or a pot-addled night listening to Sgt. Pepper.


    “We are interested in what types of information are mentioned with what frequency,” says Conway, as well as the emotions associated with those memories. The researchers are particularly interested in the respondent's age at the time the memory was encoded. Although scientists have studied “flashbulb” events such as the J.F.K. assassination, the researchers believe that with the Beatles' impact spanning generations and cultures, they can gain a broad perspective on how our personal memories develop and change. From the 3000 responses received so far, Conway says, it's clear there is “a strong reminiscence bump” in data from the over-30 population, consisting of memories from when they were about 15 to 25. Some events—such as John Lennon's murder—may be “immune to the reminiscence bump,” Conway adds.

    The results will be unveiled at the British Association for the Advancement of Science's Festival of Science, to be held 6 to 11 September in Liverpool.