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by Jean-François Cloutier, PhD

Upon my arrival as a new Faculty member at the Montreal Neurological Institute in 2004, I expected to be faced with a wide variety of complex tasks that would include setting up my laboratory, securing funding for our research program, hiring and mentoring trainees in the lab, and developing courses for undergraduate and graduate students. While all these tasks ended up being challenging, yet rewarding, none turned out to be as daunting as being a new homeowner in Montreal. Shortly after moving into our new house, I was confronted with a problem that at times seemed more complex than understanding how the brain actually works. A big skunk had made a very comfortable nest under our shed and intended on making this place its permanent residence. I was faced with two choices: take a live and let live approach and risk having to bathe my pets in tomato juice once in a while or try to gently suggest to the skunk that it may be more comfortable under someone else’s shed. I therefore scoured the web in search of humane approaches to expel the skunk from underneath my shed. My favorite technique involved leaving a radio on at all times in the shed to mimic a constant level of activity around the nest and hopefully convince it to leave. Turns out that skunks seem to enjoy talk radio and this approach, along with several others, yielded no significant success. One day, I came across an article suggesting that farmers often use urine of the fox, a natural predator of skunks, to repel skunks from their property. As a scientist at heart, I decided to attempt an “experiment” and spread a bottle of fox urine, bought from an online retailer, all around the shed. Low and behold, although my neighbors probably did not appreciate the smell very much, the urine had the expected effect and the skunk shortly left the nest to never come back. After this “experiment”, my first thought was, why would a skunk “born and raised” in Montreal be afraid of fox urine when it has probably never been exposed to such a predator?

It turns out that animals have an innate ability to avoid specific odors that are detrimental to their survival. For example, a mouse raised in a laboratory setting will avoid specific odorant molecules isolated from fox feces or spoiled food. These innate behaviors rely on the formation of very specific connections between nerve cells (neurons) located in the nose (olfactory epithelium) of the animal and neurons in the brain. These connections are generated before birth and are programmed genetically. While as humans we do not depend on innate behaviors for our survival, we rely heavily on our ability to use our senses, including vision, taste, hearing, touch and smell, to navigate the world and to process information we gather from our environment. Just as in mice, these sensory systems require the formation of precise connections between nerve cells to function properly and to give us an accurate representation of our environment. The Cloutier lab is interested in understanding how neurons form highly specific connections within the nervous system during development that allow us to interpret the information we gather from our environment and to execute complex behavioral tasks.

During development of the nervous system, neurons project long processes (axons) that navigate over long distances to find their appropriate partner neuron with which to form connections (synapses). These growing axons detect molecules in the environment that direct their growth by either attracting them to or repelling them away from specific regions of the nervous system. We are interested in understanding how specific families of these molecules affect the growth of axons and the wiring of the brain. To understand the function of these molecules, we examine their role in the wiring of the mouse olfactory system, which represents a simplified model system with a well-established circuitry, facilitating our studies. In addition, as mentioned above, pre-programmed innate behaviors in mice are regulated through the detection of odorant molecules, which allow us to gain a better understanding of the relationship that exists between wiring of the nervous system and behavior. Understanding how molecules promote the formation of accurate connections will be critical in the future development of cell-based therapies for the treatment of various neurodegenerative diseases as well as for the treatment of spinal cord injuries.

Jean-François Cloutier is Assistant Professor in the Department of Neurology and Neurosurgery and holds a Tier II Canada Research Chair. He earned his PhD in Experimental Medicine at McGill University and completed his post-doctoral training at Johns Hopkins University. JF joined the faculty at The Neuro in 2007 and has received Young Investigator awards from NARSAD and the Association of Chemoreception Science.