Published online 23 September 2010 | Nature | doi:10.1038/news.2010.489

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Linda Buck's group has now withdrawn three articles in two years.

Linda Buck shared the Nobel prize in 2004 for her work on how the brain processes odours. R. Morgan/Fred Hutchinson Cancer Research Center

Nobel laureate Linda Buck has retracted two papers that describe how the mammal brain processes smells, after she and her colleagues lost confidence in their results. One paper was published in Science in 20061, the other in the Proceedings of the National Academy of Sciences (PNAS) in 20052.

Buck shared authorship of the retracted papers with a colleague, neuroscientist Zhihua Zou, whom she employed as a postdoc from 1997 to 2005.

Zou was first author of both retracted papers, as well as of a 2001 paper published in Nature3 that was retracted in 2008. According to a statement from Buck's employers, the Fred Hutchinson Cancer Research Center in Seattle, Washington, that retraction prompted Buck and her colleagues to review the two later papers.

They "were unable to reproduce key findings in both papers", the statement says. "In addition, they found figures inconsistent with original data in the PNAS paper. Buck has therefore simultaneously retracted both the PNAS and Science paper."

"I don't think people will be surprised," says Paul Wise from Monell Chemical Senses Center in Philadelphia, Pennsylvania, who does research into how physical stimuli are translated into sensory input.

A lab divided

Zou and Buck co-authored one further paper, published in Cell in 20054, on the neural links between odour, pheromones and reproduction. According to Buck, Zou's contribution to that study was minimal and its findings are not in question.

Zou was a postdoc in Buck's lab at Harvard Medical School in Boston, Massachusetts, from 1997, and then at the Fred Hutchinson Cancer Research Center from 2002.

In a notice published in Science today5, Buck says that Zou "declined to sign this retraction". He also stood behind the 2001 paper in Nature, even though that retraction noted that the authors had "lost confidence" in the paper's findings after being unable to reproduce them6.

Until last year, Zou was an assistant professor in the department of neuroscience and cell biology at the University of Texas Medical Branch in Galveston. A department administrator said that his contract, which expired in August 2009, was not renewed in the wake of "massive layoffs" after Hurricane Ike.

Zou returned to his native China in July 2009, leaving no forwarding address, says the administrator. He could not be reached for comment.

Influential work

The paper in Science, which according to the ISI Web of Knowledge index has been cited 73 times, reported that two odours in combination stimulate a different set of neurons in the olfactory region of rats' brains to those stimulated by either odour individually.

"That was an interesting new thing," says Mats Olsson, an olfactory researcher at the Karolinska Institute in Stockholm, Sweden. "It has been debated whether odorants that are mixed give you a new perception or somehow just a combination of the two." The result might explain, for example, how perfumers can make new scents by combining ingredients.

"On the other hand, it's just a piece in the puzzle and as a researcher you should not take anything for granted when you see results once," Olsson says, adding that nonetheless, "I have to change my slides a little bit."

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"It was the first paper I'd known that had really convincing evidence for processing [in the brain] that was consistent with that phenomenon," says Wise. "I think a lot of people believe that the basic phenomenon occurs – just, I guess, this is not the addition of evidence that people have taken it to be."

The paper in PNAS, which the ISI Web of Knowledge says has been cited 61 times, mapped out how odour perception is organized in the brain. The journal has confirmed that a retraction will be published in its online early edition, but has provided no further information.

Despite the retractions, "most of the early work from Linda Buck's lab has been foundational", says Wise, referring to her research on the basic principles of olfactory perception, for which she shared the 2004 Nobel Prize in Physiology or Medicine with Richard Axel, a neuroscientist at Columbia University in New York. "Nobody questions that," says Wise.