Stephen Klassen (BSc ’13, MSc ’15) was astounded when he first heard the sound of the brain talking to blood vessels.

“It’s like if you’re in a tent, and it previously rained, and a few droplets fall off a tree onto your tent in quick succession — that’s how I can best describe the sound that neurons that control blood vessels make when they fire,” says the Assistant Professor of Kinesiology. “It captivated me.”

At the time, Klassen was a PhD student measuring electrical currents travelling from the brain to neurons, nerve cells that transmit messages throughout the body, in the body’s sympathetic nervous system (SNS).

The SNS regulates heart rate, blood pressure and blood flow — commonly known as “fight or flight” responses — during rest and in times of stress.

Now, Klassen is an expert on how the brain communicates with a large network of blood vessels that regulate blood pressure and blood flow in humans. His many accomplishments in this area have earned him Brock University’s 2025 Award for Early Career Research and Creative Activity.

“Dr. Klassen has significantly advanced understandings about sympathetic neural control of the human cardiovascular system,” says Acting Vice-President, Research Michelle McGinn. “The new findings developed through his research have important implications for understanding hypertension and developing novel treatments to lower cardiovascular risk.”

Klassen’s research aims to discover the processes enabling the SNS to regulate blood pressure and blood flow; understand how age-related failures in the SNS lead to high blood pressure and cardiovascular diseases; and study how exercise maintains brain and heart health.

A key finding in Klassen’s work is in the area of SNS “action potentials.” An action potential is a rapid rise and subsequent fall of electrical currents in the membranes of neurons. The currents, which travel from the brain through neurons to the cell, play a central role in cell-to-cell communication.

It was long thought that SNS neurons talked to blood vessels only by using bursts of a few action potentials firing at about the same time.

“Researchers assumed there was silence between bursts of action potentials,” says Klassen. “We thought, maybe that doesn’t capture the whole language that the brain uses to speak to the blood vessels.”

When he and his team took a closer look, Klassen says they found there was “a lot of communication happening between these bursts.”

The researchers published their discovery in a first-of-its-kind study.

Klassen and his team have made breakthroughs in several other areas, including:

• Developing an innovative computer program to identify patterns occurring in the baroreceptor reflex, which involves a series of steps that ensures blood pressure does not fall too low when people rapidly stand up, are startled or perform exercise.
• Discovering that alpha-2 adrenergic receptors are important for regulating the strategies used by the sympathetic nervous system to control blood pressure.
• Discovering that Neuropeptide Y, a chemical that the SNS releases in the fight or flight response, also regulates blood pressure when the body is at rest.

Klassen, who earned his undergraduate and master’s degrees at Brock, says he is grateful his work is being recognized.

“This award is an affirmation and acknowledgement that I’m on the right track and my research is making a difference,” he says. “This all came about because of the investment Brock and my mentors have made in me.”

Among those Klassen credits for his success are his wife, Erin, and his mentors, Professor of Health Sciences Deborah O’Leary, Western University Professor Kevin Shoemaker and Mayo Clinic anesthesiologist Mike Joyner.