Event Abstract Back to Event How ion-channel cooperativity can influence neuronal activity Ekaterina Zhuchkova1, 2*, Fabian Santi1, 2, Dmitry Zarubin1, 2 and Susanne Schreiber1, 2 1 Humboldt University Berlin, Institute for Theoretical Biology, Germany 2 Bernstein Center for Computational Neuroscience, Germany Individual stochastic units, so-called ion channels, are responsible for electrical signaling in the brain. Despite accumulating evidence for additional interactions between ion channels [1-2], the prevailing assumption is that ion channels act independently. Since Hodgkin and Huxley’s model of action potential (AP) initiation, it is supposed that channels change their open probability in response to a common signal such as the membrane voltage, but do not directly influence each other. Enhancing or hindering interactions between channels are known to exist and therefore consequences for neuronal spiking dynamics can be expected. Nevertheless, they have so far received relatively little attention in the analysis of excitable membranes. Naundorf et al. [3] have shown that cooperativity of sodium channels may explain the rapid onset dynamics of APs. Here, using bifurcation analysis and stochastic simulations of an extended Morris-Lecar model, we investigate from a theoretical perspective how cooperative and anticooperative gating between ion channels changes basic sub- and suprathreshold voltage dynamics [4]. The effects of channel interactions include the modification of the range of sustained firing and cell-intrinsic noise, the prolongation of AP duration, the occurrence of multistability and type-3-like firing. In contrast to modifications in channel number (insertion or blocking of ion channels), the system that modulates interactions between ion channels can maintain the same peak conductances but still drastically change its dynamics. We therefore hypothesize that channel interactions could be an efficient mechanism to regulate the neuronal activity and voltage noise. Acknowledgements This work was funded by the German Federal Ministry of Education and Research (Grants No. 01GQ0901, No. 01GQ1001A, and No. 01GQ0972) and DFG (Grants No. SFB 618 and No. GK1589).