Real-time imaging of calcium dynamics in rhythmically active neurons of thespinal network for locomotion

Abstract

Event Abstract Back to Event Real-time imaging of calcium dynamics in rhythmically active neurons of thespinal network for locomotion Di Wang1*, Sten Grillner1 and Peter Wallén1 1 Karolinska Institutet, Sweden The neuronal network underlying locomotion in vertebrates has been investigated in considerable detail in the lamprey spinal cord in vitro model. The isolated spinal cord preparation can be made to produce well-coordinated rhythmic activity, with left-right alternation and intersegmental phase-coupling, corresponding to locomotion (swimming). The rhythm-generating capacity of the network is the result of an interplay between network connectivity properties and the dynamic membrane properties of the individual network neurons. These different kinds of membrane properties typically rely on localized influx of calcium, leading to, for instance, the activation of calcium-dependent potassium channels (KCa-channels). Among the key calcium-dependent membrane properties are the NMDA-receptor-dependent membrane potential pacemaker oscillations, the slow afterhyperpolarization (sAHP) following the action potential, and the postinhibitory rebound depolarization following a period of hyperpolarization. Although much is known about the detailed operation of the network, specific information on the calcium dynamics – both in the temporal and the spatial domain – is still to a large degree lacking. We are therefore investigating different membrane properties of lamprey spinal neurons by utilizing confocal calcium imaging in combination with intracellular membrane potential recordings. During rhythmic network operation (fictive locomotion), calcium fluctuations can be detected in dendrites of individual neurons, even during subthreshold membrane potential oscillations (cf. Bacskai et al., Neuron 14:19-28, 1995). Furthermore, during NMDA-dependent pacemaker oscillations in the presence of TTX, dendritic calcium fluctuations are also seen, timed to the membrane potential oscillations (Fig. 1). During burst firing, the sAHP´s following each spike will add and produce a pronounced summed sAHP, which contributes to the termination of the burst. Calcium imaging during spike trains has revealed a distinct influx of calcium in conjunction with the sAHP. This calcium enters via N (CaV 2.2)- and P/Q (CaV 2.1) types of HVA calcium channels, while L-type channels (CaV 1) are not involved. Correspondingly, blockade of N- and P/Q-type channels reduced the calcium influx in the soma and proximal dendrites, while blockade of L-type channels did not. This indicates that the calcium channels responsible for activating the KCa channels involved in the sAHP are primarily located in the soma and proximal dendrites of the cell. In contrast, L-type calcium channels appear to be mainly localized to distal dendrites in lamprey spinal neurons. Confocal fluorescence imaging of calcium influx, and other dynamic events, with high spatial and temporal resolution, in combination with electrophysiological recordings from the same neuron in the functional network, holds promise to reveal important insights into the cellular and subcellular mechanisms governing network operation. tn_image2 conference image2 conference Conference: Neuroinformatics 2008, Stockholm, Sweden, 7 Sep - 9 Sep, 2008. Presentation Type: Poster and Short Oral Presentation Topic: Neuroimaging Citation: Wang D, Grillner S and Wallén P (2008). Real-time imaging of calcium dynamics in rhythmically active neurons of thespinal network for locomotion. Front. Neuroinform. Conference Abstract: Neuroinformatics 2008. doi: 10.3389/conf.neuro.11.2008.01.060 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: 25 Jul 2008; Published Online: 25 Jul 2008. * Correspondence: Di Wang, Karolinska Institutet, Stockholm, Sweden, di.wang@ki.se Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract Supplemental Data The Authors in Frontiers Di Wang Sten Grillner Peter Wallén Google Di Wang Sten Grillner Peter Wallén Google Scholar Di Wang Sten Grillner Peter Wallén PubMed Di Wang Sten Grillner Peter Wallén 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.