Sense of smell may tell how much longer you will live

Washington DC: A team of researchers has revealed that they were able to predict whether worms would live long by measuring how they move towards an appealing, food-like scent.

The Salk Institute finding shows how nematodes (Caenorhabditis elegans) process information about the environment and how circuits in the brain change as an animal ages.

"We're not saying that your ability to smell is going to make you live longer," says Sreekanth Chalasani, adding "but this odor behavior is likely indicative of some kind of underlying physiology."

The small C. elegans has 12 pairs of specialized neurons in its brain that detect stimuli in the environment. Scientists had previously identified individual pairs of these neurons as required for the animals to respond to attractive odors. Chalasani and his colleagues wanted to understand this entire process in more detail.

In their new work, the researchers measured the responses of all 24 neurons as C. elegans was exposed to benzaldehyde-a chemical that gives off a pleasant, almond-like smell. Surprisingly, rather than the individual pairs that had been previously shown, they found that additional neurons were also involved.

Interestingly, these cells were divided into primary and secondary neurons.

Primary neurons showed activity in response to the benzaldehyde, while secondary neurons responded to signals sent by the primary neurons. By having a neural circuit structured like this, the team hypothesizes that the worm can get better information on the strength or concentration of a smell.

Chalasani added that if the signaling between neurons ends up being important in how other organisms -including humans - age, then manipulating the nervous system may prove a fruitful way to minimize the effects of aging or rejuvenate brain functions.

"There are a lot of questions that remain about what exactly is changing as an animal ages," says researcher Sarah Leinwand. "We want to keep looking at what is changing to cause some animals to have better functioning nervous systems and to live longer."

The study will be published in the Journal eLife.