McGill physiology research team sheds light on how the brain
processes what we sense

We rely on our senses in all aspects of our lives.
Unfortunately, many people suffer from some kind of impaired
sensory function. In Canada alone, 600,000 people are visually
impaired while almost three million suffer from partial or total
hearing loss. In a paper published this week in The Journal of
Neuroscience, researchers from McGill University have demonstrated
for the first time that there are specific neurons that respond
selectively to first and second order sensory attributes. In the
visual system, for example, luminance is a first-order attribute,
whereas contrast is second-order. These findings could pave the way
to the development of novel therapies and improved prosthetics for
those with sensory deficiencies.

The research team, led by physiology student Patrick
McGillivray, recorded the responses to stimuli of midbrain
electro-sensory neurons in the weakly electric fish. Based on these
responses, the researchers were able to demonstrate that there are
specific neurons that respond selectively to different attributes
at the same time. Moreover, they uncovered the simple and generic
neural circuits that enable this selectivity. These findings
provide important clues about how the brain processes first and
second order sensory attributes in audition (like pitch and timbre)
and vision (like luminance and contrast).

“Uncovering these clues relies on identifying the attributes
that we use to perceive stimuli, the computations performed by the
brain, and the actual neural networks that implement these,”
explained Dr. Maurice Chacron, lead author and principal
investigator at McGill’s Computational Systems Neuroscience Lab.
“Stimuli like speech and music are characterized by multiple
attributes. For example, when listening to music, we can perceive
both frequency (how low or high an instrument is playing), as well
as timbre (the type of instrument playing).”

This research was supported by the Canadian Institutes of Health
Research (CIHR), the Natural Sciences and Engineering Research
Council of Canada (NSERC), the Canada Foundation for Innovation
(CFI), and the Canada Research Chairs (CRC). Katrin Vonderschen
from McGill’s Dept. of Physiology and Eric S. Fortune from Johns
Hopkins University in Baltimore, Maryland also contributed to the
study.