We have used computer modelling studies to examine the alterations of neuronal activity patterns of two model neurons when they are coupled via gap-junctions of varying coupling strength. We are particulary interested in physiologically and pathophysiologically relevant transitions between tonic firing and burst discharges and therefore have used a neuronal model with subthreshold oscillations which even shows two different types of tonic firing regimes and transitions to bursts (e.g. Braun et al. Biosystems 71: 39-50).

Our simulations elucidated that significant changes of the activity pattern can occur not only depending on the coupling strength but also on the individual neuron's internal state. Coupling of a tonic firing and a bursting neuron leads to highly variable, often chaotic pattern in both neurons, especially at intermediate coupling strength. At higher coupling strength neurons synchronize either in the tonic firing or bursting mode which depends on how close their individual dynamics are to the tonic-bursting bifurcation. We also have observed that neurons in different tonic firing modes can synchronize in burst patterns.

Supported by the Europian Union through Network of Excellence BioSim, Contract No. LSHB-CT-2004-005137