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Sniffs of simplicity

“If something doesn’t smell right, then we won’t invest.” This was a strapline from a recent brand campaign we ran that sought to highlight the simplicity of our investment process and overarching ethos. Our senses ultimately shape our perceptions and, ultimately, investing is all about perception.

Our sense of smell is incredibly important. As we've evolved, the ability to smell has helped us to work out what's safe to eat, and we've "followed our nose" to safe places. But how do we distinguish one smell from another? New research reveals that it may be simpler than we thought.

How does the nose know?

Of course, our sense of smell isn't just about the nose. The data we receive through the nose must be processed by the brain's olfactory bulb and olfactory cortex, in order for us to make sense of what we're smelling. While the brain as a whole is an amazingly complex organ, researchers have discovered that this particular process could in fact be very simple.

The business of distinguising one smell from another is complex. Our senses receive incredible amounts of data from the world around us at all times.

The research was published in the Nature Neuroscience and carried out by a team at Cold Spring Harbor Laboratory (CSHL) and the National Centre for Biological Sciences (NCBS) in Bangalore, India. Working together for five years across two continents, they have identified a key process, that could explain why the nose knows what it knows.

Overloaded senses

The business of distinguising one smell from another is complex. Our senses receive incredible amounts of data from the world around us at all times. Odours travel in what scientists call "plumes", which disperse in different ways depending on environmental conditions like wind. As well as environmental factors, our own sensory processes can vary too. Sometimes we breathe slowly and deeply, while at other times we take rapid, shallow breaths, and this also affects the amount of odour "samples" we're taking in at any given moment.

The research

The scientists worked with rats, whose olfactory system is actually very similar to our own due to a concept called evolutionary conservation. In order to investigate how rats distinguish different smells, the team removed one of the variables affecting the amount of odour samples being taken in. They devised a way to control the rats' breathing rate, which allowed them to observe how the odour identification system operates under "constant" conditions. These results were then compared to data from the same animal under normal breathing conditions. By doing this, the researchers were able to analyse how the mitral and tufted cells in a rat's olfactory bulb process data obtained from the receptors in the nose.

Simple conclusions

The team expected to find complex and non-linear calculations at work in the olfactory bulb, but the results surprised them. Assistant Professor Florin Albeanu, who directed the research, said: "We took small snippets of a given odor – a very short stimulus – and exposed rats to it".

He continued: "In a given animal, we observed the activity of a single mitral cell, trial after trial. And we found that once we could capture the response of that cell to the short stimulus, we could use that response to accurately predict how the same cell would respond – whether to a long version of the same stimulus, or to any incoming odor, no matter the shape of its plume in spatial terms, or its duration in time."

In other words, what they discovered was a linear response, and a remarkably simple process. Each cell has a "latency": a slight temporal delay before it fires or is suppressed in response to a perceived odor signal. A cell has different latencies for different odour signals, and it can identify the signature of a given smell in a matter of tenths of thousands of a second.

Rats are more dependent on their sense of smell than humans, and this research has helped scientists to understand why rat brains are so good at what they do. The answer is the simplicity at the heart of the olfactory system.

But regardless of the simplicity or otherwise of the act, we shall continue to stick avoiding investments that give off a whiff.

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