The co-operation of intrinsic and synaptic properties in brainstem locomotor command neurons

Abstract

Event Abstract Back to Event The co-operation of intrinsic and synaptic properties in brainstem locomotor command neurons Rejean Dubuc1* 1 Universite du Quebec aMontreal, Departement de Kinanthropologie, Canada Sensory stimulation is known to elicit locomotion. The locomotor bouts allow for instance an animal to escape away from a stimulus. We have examined the neural networks and cellular properties that are involved in escape locomotor behaviour in lampreys. We showed that sensory stimulation elicits sustained depolarizations in reticulospinal cells, considered to be brainstem command neurons responsible for initiating locomotion. The sustained depolarizations are triggered by glutamate transmission and the activation of NMDA receptors in reticulospinal cells results in calcium entry, which in turn activates specific intrinsic properties that are crucial for maintaining the reticulospinal cells into a depolarized state. We provided evidence that a calcium activated nonselective cationic current (ICAN) is involved. Whether such a conductance can maintain the cells depolarized for a very long time, up to minutes as seen in locomotor behaviour, was questionable and we examined the possibility that synaptic inputs could cooperate with intrinsic properties to amplify the duration of sustained depolarizations. Ascending spinal inputs to reticulospinal cells were reversibly blocked by applying xylocaine over the rostral spinal cord segments. Under this condition, the duration of the sustained depolarizations was markedly reduced. The contribution of excitatory glutamatergic inputs was then assessed by applying CNQX and AP- 5 over one of two simultaneously recorded bilaterally homologous reticulospinal cells. The amplitude of sensory-evoked depolarization decreased significantly in the cell exposed to the antagonists compared to the contralateral control reticulospinal cell. In contrast, local application of glycine produced a transient membrane potential hyperpolarization, but did not end the sustained depolarization. Locally applied strychnine did not change the duration of the sustained depolarizations. Application of GABA did not abolish the sustained depolarizations and thus mechanisms other than glycinergic or GABAergic inhibition are needed to end the sustained depolarizations in reticulospinal cells. Taken together, our results suggest that ascending excitatory spinal inputs cooperate with intrinsic properties of reticulospinal cells to maintain the cells depolarized for a prolong time after sensory activation. Behaviourally, this would permit to sustain long bouts of escape swimming. Conference: 3rd Mediterranean Conference of Neuroscience , Alexandria, Egypt, 13 Dec - 16 Dec, 2009. Presentation Type: Oral Presentation Topic: Symposium 05 – Interactions of synaptic and intrinsic properties in rhythmic motor activities Citation: Dubuc R (2009). The co-operation of intrinsic and synaptic properties in brainstem locomotor command neurons. Front. Neurosci. Conference Abstract: 3rd Mediterranean Conference of Neuroscience . doi: 10.3389/conf.neuro.01.2009.16.032 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Nov 2009; Published Online: 19 Nov 2009. * Correspondence: Rejean Dubuc, Universite du Quebec aMontreal, Departement de Kinanthropologie, Beauport, Qc G1J 2G3, Canada, rejean.dubuc@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Rejean Dubuc Google Rejean Dubuc Google Scholar Rejean Dubuc PubMed Rejean Dubuc Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.