Emotion Makes Nose a Sharper Smeller

Know how a whiff of certain odors can take you back in time, either to a great memory or bad one? It turns out emotion plays an even bigger role with the nose, and that your sense of smell actually can sharpen when something bad happens.

Northwestern University researchers proved the surprising connection by giving volunteers electric shocks while they sniffed novel odors.

The discovery, reported in Friday's edition of the journal Science, helps explain how our senses can steer us clear of danger. More intriguing, it could shed light on disorders such as post-traumatic stress syndrome.

"This is an incredibly unique study," said Dr. David Zald, a Vanderbilt University neuroscientist who studies how the brain handles sensory and emotional learning. "We're talking about a change in our perceptual abilities based on emotional learning."

Scientists long have known of a strong link between the sense of smell and emotion. A certain perfume or scent of baking pie, for instance, can raise memories of a long-dead loved one.

Conversely, a whiff of diesel fuel might trigger a flashback for a soldier suffering PTSD.

Could an emotionally charged situation make that initial cue be perceived more strongly in the first place?

The research team recruited 12 healthy young adults to find out.

Volunteers repeatedly smelled sets of laboratory chemicals with odors distinctly different from ones in everyday life. An "oily grassy" smell is the best description that lead researcher Wen Li, a Northwestern postdoctoral fellow in neuroscience, could give.

Two of the bottles in a set contained the same substance and the third had a mirror image of it, meaning its odor normally would be indistinguishable. By chance, the volunteers correctly guessed the odd odor about one-third of the time.

Then Li gave the volunteers mild electric shocks while they smelled just the odd chemical. In later smell tests, they could correctly pick out the odd odor 70 percent of the time.

MRI scans showed the improvement was more than coincidence. There were changes in how the brain's main olfactory region stored the odor information, essentially better imprinting the shock-linked scent so it could be distinguished more quickly from a similar odor.

In other words, the brain seems to have a mechanism to sniff out threats.

That almost is certainly a survival trait evolved to help humans rapidly and subconsciously pick a dangerous odor from the sea of scents constantly surrounding us, Li said. Today, that might mean someone who has been through a kitchen fire can tell immediately if a whiff of smoke has that greasy undertone or simply comes from the fireplace.

But the MRI scans found the brain's emotional regions did not better discriminate among the different odors, Li noted. That discrepancy between brain regions is where anxiety disorders may come in. If someone's olfactory region does not distinguish a dangerous odor signal from a similar one, the brain's emotional fight-or-flight region can overreact.

Researchers say that is a theory not yet tested.

For now, Northwestern neuroscientist Jay Gottfried, the study's senior author, says the work illuminates a sense that society too often gives short shrift.

"People really dismiss the sense of smell," said Gottfried, who researches "how the brain can put together perceptions of hundreds of thousands of different smells. ... Work like this really says that the human sense of smell has much more capacity than people usually give it credit."

Genes Key to Future Cancer Treatment

BARCELONA, Spain) — The treatment that more cancer patients receive may one day depend on their genes.
With an increasing number of biological clues available, doctors hope they will be able to customize more patients' treatments based on their genetic profiles.
In research presented at a meeting of the European Cancer Organization in Barcelona, experts said this week that these clues will help doctors determine not only which patients will probably develop cancer, but even those who will relapse, or be suitable for specific treatments.
"We are going to witness a revolution in cancer treatment," said Dr. Martine Piccart, head of medicine at the Institut Jules Bordet in Belgium. "In a few years, we will be able to fully demonstrate how powerful these new technologies are."
The real test, however, will be if doctors can then figure out what to do next.
"It's never encouraging to say to a patient that she's going to do poorly because of her genes," Piccart said. "We need to be able to offer patients an effective treatment."
Piccart and colleagues have been working to confirm the genetic sequences for women susceptible to breast cancer.
Tailoring treatment based on patients' genes is being used now on a limited basis. Doctors have been deciding how to treat women with breast cancer depending on their tumor type for the last few years. A simple genetic test can identify breast cancer patients who will actually benefit from chemotherapy, making the toxic side effects worthwhile.
But learning more about breast cancer has also given experts new tools to fight other cancers.
A study presented at the Barcelona meeting Tuesday found an unexpected twist: patients with a certain overactive breast cancer gene were also less likely to respond to chemotherapy for lung cancer.
"We know quite a bit about breast cancer genes, and now we're looking into the black box of what role they might play in other cancers," said Dr. Gordon McVie, a cancer expert at the European Institute of Oncology.
The problem, McVie said, is that even though researchers may understand a little about what a thousand of the genes involved in cancer do, there are about 31,000 others that they don't.
Other studies presented in Barcelona on Tuesday identified genes that could triple a woman's risk of ovarian cancer, as well as molecular profiling to predict which colon cancer patients would benefit from chemotherapy.
Cancer is an incredibly complicated disease, and is influenced by other variables like diet and environmental exposure. Even if researchers can identify the genetic components responsible, many factors remain beyond doctors' control.
"We haven't had any big genetic hits," McVie said, explaining that while scientists have identified genes that predispose people to cancers including breast, bowel, ovarian and colon, those make up only a small amount of all cancers.
"Cracking the genetic code is still a very imprecise science," he said.
Also, on Monday, German researchers said they had developed a test to identify cancer cells circulating in the blood of breast cancer patients. That could potentially enable doctors to catch cancer cells en route to another location — and give them time to intervene to prevent a tumor.
Dr. Julia Juckstock and colleagues at the University of Munich analyzed blood samples from 1,767 women with breast cancer before treatment and compared them to samples taken after about half of them had completed chemotherapy. Preliminary results found evidence of tumor cells in transport in less than 10 percent of the treated patients.
"This is a fascinating development," said Dr. John Smyth, a professor of medical oncology at the University of Edinburgh, who was unconnected to the Munich study.
Instead of a blanket approach to treatment, Smyth said that the test could help doctors pinpoint those women in whom breast cancer was likely to spread and needed extra care.