title: A novel neural substrate for the transformation of olfactory inputs into motor output.
abstract: It is widely recognized that animals respond to odors by generating or modulating specific motor behaviors. These reactions are important for daily activities, reproduction, and survival. In the sea lamprey, mating occurs after ovulated females are attracted to spawning sites by male sex pheromones. The ubiquity and reliability of olfactory-motor behavioral responses in vertebrates suggest tight coupling between the olfactory system and brain areas controlling movements. However, the circuitry and the underlying cellular neural mechanisms remain largely unknown. Using lamprey brain preparations, and electrophysiology, calcium imaging, and tract tracing experiments, we describe the neural substrate responsible for transforming an olfactory input into a locomotor output. We found that olfactory stimulation with naturally occurring odors and pheromones induced large excitatory responses in reticulospinal cells, the command neurons for locomotion. We have also identified the anatomy and physiology of this circuit. The olfactory input was relayed in the medial part of the olfactory bulb, in the posterior tuberculum, in the mesencephalic locomotor region, to finally reach reticulospinal cells in the hindbrain. Activation of this olfactory-motor pathway generated rhythmic ventral root discharges and swimming movements. Our study bridges the gap between behavior and cellular neural mechanisms in vertebrates, identifying a specific subsystem within the CNS, dedicated to producing motor responses to olfactory inputs.
authors.affiliation: Department of Kinesiology, Université du Québec à Montréal, Montréal, Québec, Canada.
authors.forename: Dominique
authors.initials: D
authors.lastname: Derjean
authors.forename: Aimen
authors.initials: A
authors.lastname: Moussaddy
authors.forename: Elias
authors.initials: E
authors.lastname: Atallah
authors.forename: Melissa
authors.initials: M
authors.lastname: St-Pierre
authors.forename: François
authors.initials: F
authors.lastname: Auclair
authors.forename: Steven
authors.initials: S
authors.lastname: Chang
authors.forename: Xiang
authors.initials: X
authors.lastname: Ren
authors.forename: Barbara
authors.initials: B
authors.lastname: Zielinski
authors.forename: Réjean
authors.initials: R
authors.lastname: Dubuc
mesh_terms: D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology; D005260:Female; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000502:physiology; D009812:Odorants; D009830:Olfactory Bulb / Q000033:anatomy & histology / Q000502:physiology; D009833:Olfactory Pathways / Q000033:anatomy & histology* / Q000502:physiology*; D048428:Petromyzon / Q000033:anatomy & histology* / Q000502:physiology*; D010675:Pheromones / Q000502:physiology*; D012154:Reticular Formation / Q000033:anatomy & histology* / Q000502:physiology; D012903:Smell; D013116:Spinal Cord / Q000033:anatomy & histology / Q000502:physiology
chemical_list: D010675:Pheromones