Multimodal encoding in a simplified model of intracellularcalcium signaling

摘要

Many cells use calcium signaling to carryinformation from the extracellular side of the plasmamembrane to targets in their interior. Since virtually allcells employ a network of biochemical reactions for Ca~(2+)signaling, much effort has been devoted to understand thefunctional role of Ca~(2+)responses and to decipher how theircomplex dynamics is regulated by the biochemical networkof Ca~(2+)-related signal transduction pathways. Experimen-tal observations show that Ca~(2+)signals in response toexternal stimuli encode information via frequency modu-lation (FM) or alternatively via amplitude modulation(AM). Although minimal models can capture separatelyboth types of dynamics, they fail to exhibit different andmore advanced encoding modes. By arguments of bifur-cation theory, we propose instead that under somebiophysical conditions more complex modes of informa-tion encoding can also be manifested by minimal models.We consider the minimal model of Li and Rinzel and showthat information encoding can occur by AM of Ca~(2+)oscillations, by FM or by both modes (AFM). Our work ismotivated by calcium signaling in astrocytes, the pre-dominant type of cortical glial cells that is nowadaysrecognized 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 betterunderstanding of synaptic information transfer. Further-more, our results might also be important for better insighton other examples of physiological processes regulated byCa~(2+)signaling.