Effects of rapid buffers on Ca2+ diffusion and Ca2+ oscillations

Wagner, John; Keizer, Joel

doi:10.1016/s0006-3495(94)80500-4

Cited by 442 publications

(354 citation statements)

References 35 publications

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“…In spines and the adjacent dendrites, the amplitudes of the Ca 2ϩ transients are enhanced, and the time course is markedly faster. This distortion is predicted by the absence of a rapid Ca 2ϩ buffer (Wagner and Keizer, 1994).…”

Section: Discussionmentioning

confidence: 99%

Calbindin in Cerebellar Purkinje Cells Is a Critical Determinant of the Precision of Motor Coordination

et al. 2003

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Section: Discussionmentioning

confidence: 99%

Calbindin in Cerebellar Purkinje Cells Is a Critical Determinant of the Precision of Motor Coordination

et al. 2003

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“…Quantitatively, however, k off is significantly underestimated in the case of high-affinity binding to the membrane (large q and r). This is because tight binding effectively slows down diffusion in the cytosol (similar effects are discussed in [27,28]). Not surprisingly, the estimate is skewed most of all when the highaffinity binding is combined with large k off because this case is the exact opposite of the situation where the cytosolic diffusion is fast compared to the rate of unbinding.…”

mentioning

confidence: 83%

Diffusion on a curved surface coupled to diffusion in the volume: Application to cell biology

Novak

Gao

Choi

et al. 2007

Journal of Computational Physics

106

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An algorithm is presented for solving a diffusion equation on a curved surface coupled to diffusion in the volume, a problem often arising in cell biology. It applies to pixilated surfaces obtained from experimental images and performs at low computational cost. In the method, the Laplace-Beltrami operator is approximated locally by the Laplacian on the tangential plane and then a finite volume discretization scheme based on a Voronoi decomposition is applied. Convergence studies show that mass conservation built in the discretization scheme and cancellation of sampling error ensure convergence of the solution in space with an order between 1 and 2. The method is applied to a cellbiological problem where a signaling molecule, G-protein Rac, cycles between the cytoplasm and cell membrane thus coupling its diffusion in the membrane to that in the cell interior. Simulations on realistic cell geometry are performed to validate, and determine the accuracy of, a recently proposed simplified quantitative analysis of fluorescence loss in photobleaching. The method is implemented within the Virtual Cell computational framework freely accessible at www.vcell.org.

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“…Here [Ca] is the intracellular calcium concentration in μM, f Ca =0.03 ms −1 is a constant reflecting fraction of bounded to free Ca 2+ (Wagner and Keizer 1994), α=0.0055 μM/ (μA/cm 2 ) is the Ca 2+ conversion constant, and k ex =1 μM −1 is the Ca extrusion ratio (Nowak et al 1984;Mayer and Westbrook 1987;Reynolds and Miller 1990). The model was simulated using an Euler-Maruyama integration algorithm (Kloeden and Platen 1999) with integration time step dt=0.0025 ms.…”

Section: Mathematical Modelingmentioning

confidence: 99%

In vivo conditions influence the coding of stimulus features by bursts of action potentials

Akerberg

Chacron

2011

J Comput Neurosci

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The functional role of burst firing (i.e. the firing of packets of action potentials followed by quiescence) in sensory processing is still under debate. Should bursts be considered as unitary events that signal the presence of a particular feature in the sensory environment or is information about stimulus attributes contained within their temporal structure? We compared the coding of stimulus attributes by bursts in vivo and in vitro of electrosensory pyramidal neurons in weakly electric fish by computing correlations between burst and stimulus attributes. Our results show that, while these correlations were strong in magnitude and significant in vitro, they were actually much weaker in magnitude if at all significant in vivo. We used a mathematical model of pyramidal neuron activity in vivo and showed that such a model could reproduce the correlations seen in vitro, thereby suggesting that differences in burst coding were not due to differences in bursting seen in vivo and in vitro. We next tested whether variability in the baseline (i.e. without stimulation) activity of ELL pyramidal neurons could account for these differences. To do so, we injected noise into our model whose intensity was calibrated to mimic baseline activity variability as quantified by the coefficient of variation. We found that this noise caused significant decreases in the magnitude of correlations between burst and stimulus attributes and could account for differences between in vitro and in vivo conditions. We then tested this prediction experimentally by directly injecting noise in vitro through the recording electrode. Our results show that this caused a lowering in magnitude of the correlations between burst and stimulus attributes in vitro and gave rise to values that were quantitatively similar to those seen under in vivo conditions.While it is expected that noise in the form of baseline activity variability will lower correlations between burst and stimulus attributes, our results show that such variability can account for differences seen in vivo. Thus, the high variability seen under in vivo conditions has profound consequences on the coding of information by bursts in ELL pyramidal neurons. In particular, our results support the viewpoint that bursts serve as a detector of particular stimulus features but do not carry detailed information about such features in their structure.

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Effects of rapid buffers on Ca2+ diffusion and Ca2+ oscillations

Cited by 442 publications

References 35 publications

Calbindin in Cerebellar Purkinje Cells Is a Critical Determinant of the Precision of Motor Coordination

Calbindin in Cerebellar Purkinje Cells Is a Critical Determinant of the Precision of Motor Coordination

Diffusion on a curved surface coupled to diffusion in the volume: Application to cell biology

In vivo conditions influence the coding of stimulus features by bursts of action potentials

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