Neural dynamic simulation by object-oriented model

The ionic channels on the membrane of neuronal cells are functional significance to their dynamic responses and specific patterns of action potentials. To understand the dynamics of calcium concentration, cell volume and pH homeostasis and their effects of electrical activities, we proposed and implemented an integrated neuronal model, which build up a general class of neuron with configurable ionic channels as conceptual counterpart of object-oriented approach. This model includes nine ionic currents. There are five outward potassium currents (including delayed-rectifier, transient, muscarinic, calcium activated, and after-hyperpolarization currents), two inward currents (including sodium and calcium currents), a NMDA current, and a leakage current. Calcium concentration dynamics, volume and pH regulation mechanisms (including Na⁺-K⁺ pump and Na⁺-H⁺ exchanger) are also taken into considerations in this model. The simulation program is developed with Visual C++(Microsoft Ver. 4.0) using graphic user interface to adjust model parameters and display results. The parameters of different neurons are stored in a database file (Microsoft Access 7.0) which can be read by the program and can be modified to fit various neuronal types. The simulation results can be easily configured to realize the effects and contributions of ionic channels to action potentials. The action potentials of several types of neuron can be simulated through adjusting model parameters. The dynamics of the cell volume and pH can also be observed. To pursuit the possible hardware implementation by CMOS technology, the fundamental concept is transformed into HSPICE model with CMOS device. The simulation results confirm the possible realization of a nuron-like hardware device by regulation of ionic channels.