March 29, 2012
Photo credit: Luther Caverly

The cocktail party analogy

Richard Dansereau has a theory. And it’s set at a cocktail party. A soirée complete with the usual distractions like people coming and going, interrupting conversation. Of course, there’s the one guest who always talks and laughs the loudest.

“At a cocktail party, you have lots of people, groups of people talking together, it’s hard to focus on one conversation when the brain is being bombarded with speech signals all around,” explains Richard Dansereau, a professor in the Faculty of Engineering and Design.

The reason for the party
“By understanding this concept of knowing where to focus one’s attention when competing information and signals surround us, we can apply it to various medical fields, both clinical and engineering,” explains Dansereau.

Like medical engineers investigating prostheses. One of the challenges professionals in this field face is filtering out unwanted messages. For example, those sent by surrounding muscles that may be unnecessary for the movement of the prosthetic limb.

“Several muscles are activated and several signals are sent, but what we really need to concentrate on is the focused signal to a specific muscle and block out the surrounding signals, or side conversations,” explains Dansereau.

By understanding this concept of knowing where to focus one’s attention when competing information and signals surround us, we can apply it to various medical fields, both clinical and engineering

Interrupting the conversation

And Dansereau goes on to apply the cocktail party analogy to clinical applications as well, including understanding muscle abnormalities, or any disease where the nerve signal is not correctly sent to the muscle.

He uses Muscular Dystrophy patients as an example.

“Each nerve signal activates hundreds of muscle motor units, and ideally all units should be doing the same thing. However, this isn’t always the case. So we’re hoping to break down the recorded signals into motor unit activations to understand what’s happening inside the body,” explains Dansereau.

So to make this job easier, Dansereau and Adrian Chan, a biomedical engineer in the Faculty of Engineering, are co-supervising a PhD student in the process of developing a methodology to separate motor units.

“By taking multiple recordings from different parts of the muscles, we’re taking a multi-channel approach to understanding the motor units,” explains Chan. “Since each motor unit action potential has a different shape we can identify the motor units, extract information, and determine any abnormalities.”

By taking multiple recordings from different parts of the muscles, we’re taking a multi-channel approach to understanding the motor units

In other words, the methodology will provide an automated tool for various health-care professionals, improving speed and reliability of analyses, says Chan.

Funded by an NSERC Discovery Grant, Dansereau and Chan, along with their team of graduate students and colleagues, are hoping these results will provide medical practitioners with possible treatment options and diagnosis.

A diverse group of invitees

To keep the party exciting, a group of researchers are involved. Like Carleton biologist Jeff Dawson. Research from his lab is focused on understanding insect flight and flight muscles and will contribute valuable information that will allow the team to understand human muscle signals. (See more of Dawson’s related research in this video)

As Dawson explains, the goal is to understand the link between neural processing of environmental sensory information in the brain and the neural signals sent from the brain that activate the wing muscles causing the wings to move and generate aerodynamic forces for coordinated flight.

“Insect nervous and muscular systems are simpler, relative to humans, and thus provide opportunities to study fundamental principles unique to both,” explains Dawson.

Of course it only makes sense that students are also involved in the research. As an NSERC USRA student, Marina Gobrial was tasked with developing a program to decompose locust EMG signals by finding all motor unit action potentials (MUAP), separating them and putting them into categories which could later be used to record the frequency they were firing at and any changes over time, she explains.

The one who laughs and talks the loudest
With funding from NSERC, Dansereau and his team are applying the cocktail party analogy to another clinical setting, one that involves an electro-cardio gram and trying to monitor a fetus’ heart signal.

“When monitoring an unborn baby’s heart signal, the strength of the mother’s heart beat masks that of the fetus, making it difficult to obtain an accurate reading,” says Dansereau.

Research findings will assist doctors in determining any possible problems stemming from the baby’s heart signal, he says.

The venue
And like the unique projects that are underway, the venue is also unique. Working from a lab sponsored by Texas Instruments, Carleton University is one of the “elite partners,” states Dansereau proudly. But it’s not just researchers that have use of this lab. It’s also a teaching lab for both graduate and undergraduate courses.

And the Texas Instruments lab became even more elite when it relocated to the newly built Canal Building in January 2012.

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