Smell and behaviour: the scents of taking action

Credit: Jeremy Monroe

In 5 seconds

Scientists from UdeM and University of Windsor have discovered a neural pathway that links olfaction to locomotion in fish.

In all animals, including humans, smell – the oldest of the five senses – plays a predominant role in many behaviors essential for survival and reproduction. It has been known since ancient times that animals react to odours.

Yet researchers are just beginning to elucidate the neural pathways and mechanisms responsible for odour-induced behavior. A first step was made by showing the existence of a neural pathway connecting the olfactory and motor centers of the brain in invertebrates with the worm C. elegans and in vertebrates with the lamprey, a primitive, eel-like fish native to the Atlantic Ocean.

In a new study published in PLoS Biology, scientists at UdeM and the University of Windsor show that an inhibitory circuit that releases the neurotransmitter GABA into the olfactory bulb strongly modulates behavioural responses to odours in lampreys. The study of these modulatory mechanisms allowed the researchers to discover a new pathway linking together olfactory and motor centers in the brain.

This discovery demonstrates that odours can activate locomotor centers via two distinct brain pathways,” said lead author Gheylen Daghfous, a researcher in the laboratory of UdeM neuroscience professor Réjean Dubuc. “This work sheds new light on the evolution of the olfactory system in vertebrates.”

He added: “It is well-known that animals are attracted to odors, whether it be a dog tracking its prey or a shark attracted to blood. On the other hand, we are only beginning to understand how the brain uses odors to produce behavior. Our study revealed a new brain highway dedicated to transmitting smell information to the regions controlling movements.”

Funded by the Great Lake Fishery Commission (GLFC), with the Canadian Institutes of Health Research (CIHR) and the Natural Sciences Research Council of Canada (NSERC), the study is the result of a long-standing collaboration between Dubuc and Windsor’s Barbara Zielinski.

“Our purpose was to identify the neural circuitry linking olfaction to locomotion in lampreys,” a parasitic type of fish that attach themselves to other fish and suck their blood, leaving a gaping wound, said Dubuc. “Lampreys invaded the Great Lakes decades ago and have decimated large populations of fish, with major commercial impact. The GLFC is looking for new means to control lamprey populations, and attracting them using olfactory stimuli is one such avenue.”

About this study

"GABAergic modulation of olfactomotor transmission in lampreys," by Gheylen Daghfous, Réjean Dubuc et al, was published Oct. 4, 2018 in PLoS Biology. https://doi.org/10.1371/journal.pbio.2005512

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