Multimodal encoding in a simplified model of intracellular calcium signaling
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Many cells use calcium signaling to carry information from the extracellular side of the plasma membrane to targets in their interior. Since virtually all cells employ a network of biochemical reactions for Ca2+ signaling, much effort has been devoted to understand the functional role of Ca2+ responses and to decipher how their complex dynamics is regulated by the biochemical network of Ca2+-related signal transduction pathways. Experimental observations show that Ca2+ signals in response to external stimuli encode information via frequency modulation (FM) or alternatively via amplitude modulation (AM). Although minimal models can capture separately both types of dynamics, they fail to exhibit different and more advanced encoding modes. By arguments of bifurcation theory, we propose instead that under some biophysical conditions more complex modes of information encoding can also be manifested by minimal models. We consider the minimal model of Li and Rinzel and show that information encoding can occur by AM of Ca2+ oscillations, by FM or by both modes (AFM). Our work is motivated by calcium signaling in astrocytes, the predominant type of cortical glial cells that is nowadays recognized to play a crucial role in the regulation of neuronal activity and information processing of the brain. We explain that our results can be crucial for a better understanding of synaptic information transfer. Furthermore, our results might also be important for better insight on other examples of physiological processes regulated by Ca2+ signaling.
KeywordsCalcium Information encoding Astrocyte Bifurcation Li-Rinzel
The authors thank V. Parpura, G. Carmignoto, B. Ermentrout, B. Sautois and N. Raichman for insightful conversations on Ca2+ dynamics and its capability of encoding information. V. Volman acknowledges the support of U.S. National Science Foundation I2CAM International Materials Institute Award, grant DMR-0645461. This research has been supported by the Tauber Fund at Tel Aviv University, by the Maguy-Glass Chair in Physics of Complex Systems, and by he NSF-sponsored Center for Theoretical Biological Physics (grant nos. PHY-0216576 and PHY-0225630).
- Edelstein-Keshet L (1988) Mathematical models in biology, 1st edn. The Random House, New YorkGoogle Scholar
- Guckenheimer G, Holmes P (1986) Nonlinear oscillations, dynamical systems, and bifurcations of vector fields, 2nd edn. Springer, New YorkGoogle Scholar
- Hille B (2001) Ion channels of excitable membranes, 3rd edn. Sinauer Associates, Inc, SunderlandGoogle Scholar
- Izhikevich EM (2007) Dynamical systems in neuroscience: the geometry of excitability and bursting. The MIT Press, CambridgeGoogle Scholar
- Kuznetsov Y (1998) Elements of applied bifurcation theory, 2nd edn. Springer, New YorkGoogle Scholar
- Ono N, Abe M, Ando S (1999) AM-FM extraction based on logarithmic differential decomposition. 1999 IEEE 3rd Workshop on Multimedia Signal Processing, pp. 233–238. doi: 10.1109/MMSP.1999.793838
- Parpura V (2004) Glutamate-mediated bi-directional signaling between neurons and astrocytes. In: Hatton GI, Parpura V (eds) Glial-neuronal signaling. Kluwer Academic Publisher, Boston, pp 365–396Google Scholar
- Perko L (2001) Differential equations and dynamical systems, 3rd edn. Springer, New YorkGoogle Scholar
- Rinzel J, Ermentrout BG (1989) Analysis of neural excitability and oscillations. In: Koch C, Segev I (eds) Methods in neuronal modeling: from synapses to networks. The MIT Press, Cambridge, pp 135–170Google Scholar