Stellate cells (SCs) of the medial entorhinal cortex (layer II) display mixed-mode oscillatory activity, subthreshold oscillations (small-amplitude) interspersed with spikes (large amplitude), at theta frequencies (8-12 Hz). In this paper we study the mechanism of generation of such patterns in an SC biophysical (conductance-based) model. In particular, we show that the mechanism is based on the three-dimensional canard phenomenon and that the subthreshold oscillatory phenomenon is intrinsically nonlinear, involving the participation of both components (fast and slow) of a hyperpolarization-activated current in addition to the voltage and a persistent sodium current. We discuss some consequences of this mechanism for the SC intrinsic dynamics as well as for the interaction between SCs and external inhibitory inputs.
All Science Journal Classification (ASJC) codes
- Modeling and Simulation
- Folded node
- Mixed-mode oscillations
- Theto rhythm