@article {3926,
	title = {Cell type-specific relationships between spiking and [Ca2+]i in neurons of the Xenopus tadpole olfactory bulb.},
	journal = {The Journal of Physiology},
	volume = {582},
	year = {2007},
	month = {2007 Jul 1},
	pages = {163-75},
	abstract = {<p>Multi-neuronal recordings with Ca2+ indicator dyes usually relate [Ca2+]i to action potentials (APs) assuming a stereotypical dependency between the two. However, [Ca2+]i affects and is affected by numerous complex mechanisms that differ from cell type to cell type, from cell compartment to cell compartment. Moreover, [Ca2+]i depends on the specific way a cell is activated. Here we investigate, by combining calcium imaging and on-cell patch clamp recordings, the relationship between APs (spiking) and somatic [Ca2+]i in mitral and granule cells of the olfactory bulb in Xenopus laevis tadpoles. Both cell types exhibit ongoing and odour-modulated [Ca2+]i dynamics. In mitral cells, the occurrence of APs in both spontaneous and odour-evoked situations correlates tightly to step-like [Ca2+]i increases. Moreover, odorant-induced suppression of spontaneous firing couples to a decrease in [Ca2+]i. In contrast, granule cells show a substantial number of uncorrelated events such as increases in [Ca2+]i without APs occurring or APs without any effect upon [Ca2+]i. The correlation between spiking and [Ca2+]i is low, possibly due to somatic NMDAR-mediated and subthreshold voltage-activated Ca2+ entries, and thus does not allow a reliable prediction of APs based on calcium imaging. Taken together, our results demonstrate that the relationship between somatic [Ca2+]i and APs can be cell type specific. Taking [Ca2+]i dynamics as an indicator for spiking activity is thus only reliable if the correlation has been established in the system of interest. When [Ca2+]i and APs are precisely correlated, fast calcium imaging is an extremely valuable tool for determining spatiotemporal patterns of APs in neuronal population.</p>
},
	keywords = {Action Potentials, Amino Acids, Animals, Calcium, Calcium Signaling, Fluorescence, Intracellular Fluid, Kinetics, Larva, Microscopy, Neurons, Odors, Olfactory Bulb, Olfactory Mucosa, Patch-Clamp Techniques, Reproducibility of Results, Smell, Xenopus laevis},
	issn = {0022-3751},
	doi = {10.1113/jphysiol.2006.125963},
	author = {Lin, Bei-Jung and Chen, Tsai-Wen and Schild, Detlev}
}
