Scent explained mathematically

Jul 26, 2010
Scent explained mathematically

(PhysOrg.com) -- An interdisciplinary team of neurobiologists and mathematicians from the Friedrich Miescher Institute for Biomedical Research (FMI, Switzerland) has managed to mathematically describe an important basic computation in the brain: pattern decorrelation. Their mathematical model provides a sound explanation for former observations in the olfactory bulb. The results have been published recently in the renowned scientific journal Nature Neuroscience.

When Carl Friedrich Gauss calculated the orbit and predicted the exact position of the dwarf planet Ceres in 1801 based on data collected by astronomer Giuseppe Piazzi, Europe was in awe. Gauss' ability to mathematically describe a natural phenomenon inspired people much more than his equally brilliant number theory. Two hundred years later, orbital prediction and astronomical computation are no longer such a tough nut to crack. But many biological processes, such as cognitive processes in the brain, are still elusive to and hence a deeper understanding.

Now, the small team of neurobiologists and managed to mathematically understand pattern decorrelation, a fundamental computation in the brain, which also has many applications in computer science and engineering. Previously, the group at FMI studied decorrelation in the and found that it makes representations of odors in the brain more distinct. Without decorrelation, discriminating odors would be much more cumbersome. However, the mechanisms underlying decorrelation are complicated by non-linearity and so-called recurrent connectivity through which neurons can influence each other in a complex fashion. So far, the meaning of this arrangement has not been understood.

Martin Wiechert, the mathematician in Rainer Friedrich's group, has now cracked this problem. His , published in Nature Neuroscience, shows that decorrelation emerges naturally from two features of recurrent : sparse connections and high spontaneous activity.

"We have known for a while from observations that activity is high and connectivity sparse within the olfactory bulb. But we did not know why this is the case," comments Rainer Friedrich, FMI Group Leader and supervisor of the study. "Our mathematical results allow us to explain not only the structure of neuronal circuits in the but also to understand better what happens when we smell."

Biologically relevant processes are difficult to explain mathematically not merely because of their complexity, but also because the data necessary to test the mathematical principles is often missing. "Our laboratory is uniquely predisposed for such a study. We have been able to measure activity in individual neurons very efficiently with optical methods for a while now. Such data is crucial to develop mathematical circuit models," explains Friedrich. "As the project progressed, experimentation and development cross-fertilized each other. Based on the mathematical studies we devised experiments and were able to provide the data to confirm or rebut mathematical reasoning. In exchange, we received mathematically validated information on how neuronal circuits work."

While mechanisms of decorrelation are now understood, other neuronal processes such as learning or memory still await mathematical explanation. Rainer Friedrich's lab is perfectly equipped to address these questions as well.

Explore further: Celebrities in 'Ice Bucket Challenge' to fight disease

More information: Publication in Nature Neuroscience www.nature.com/neuro/journal/v… rent/pdf/nn.2591.pdf

Provided by Friedrich Miescher Institute for Biomedical Research

4.3 /5 (3 votes)
add to favorites email to friend print save as pdf

Related Stories

Odors classified by networks of neurons

May 04, 2010

(PhysOrg.com) -- Scientists at the Friedrich Miescher Institute for Biomedical Research (FMI), are unraveling how odors are processed by the brain. As they report in Nature, odors in the olfactory brain are cl ...

Olfactory bulb size may change as sense of smell changes

Jun 16, 2008

The olfactory bulb in the brain appears to change in size in a way that corresponds to individual alterations in sense of smell, according to a report in the June issue of Archives of Otolaryngology–Head & Neck Surgery.

How fast can a rat smell?

Apr 08, 2008

Using an ethologically relevant task—exploratory sniffing—Daniel Wesson and colleagues from Boston University discovered that rats are able to discriminate odors much more quickly than previously thought, ...

Visualizing brain processes with new techniques

Sep 09, 2009

(PhysOrg.com) -- The brain's magic is worked by neural circuits, where information is transmitted from one nerve cell to the next. In the heat of the summer, for example, our ability to relish an ice cream ...

Modeling how we see natural scenes

May 21, 2008

Sophisticated mathematical modeling methods and a “CatCam” that captures feline-centric video of a forest are two elements of a new effort to explain how the brain’s visual circuitry processes real scenes. The new model ...

Recommended for you

Common infections tied to some stroke risk in kids

9 hours ago

A new study suggests that colds and other minor infections may temporarily increase stroke risk in children. The study found that the risk of stroke was increased only within a three-day period between a ...

Celebrities in 'Ice Bucket Challenge' to fight disease

20 hours ago

Steven Spielberg, Justin Bieber and Bill Gates are among many celebrities pouring buckets of ice water over their heads and donating to fight Lou Gehrig's disease, in a fundraising effort that has gone viral.

Study helps explain why elderly have trouble sleeping

21 hours ago

As people grow older, they often have difficulty falling asleep and staying asleep, and tend to awaken too early in the morning. In individuals with Alzheimer's disease, this common and troubling symptom ...

Targeted brain training may help you multitask better

23 hours ago

The area of the brain involved in multitasking and ways to train it have been identified by a research team at the IUGM Institut universitaire de gériatrie de Montréal and the University of Montreal.

User comments : 0