EFFECTS OF INDUCED ELECTRIC-FIELDS ON FINITE NEURONAL STRUCTURES - A SIMULATION STUDY

In this paper we present an analysis of magnetic stimulation of finite length neuronal structures using computer simulations. Models of fini te neuronal structures in the presence of extrinsically applied electr ic fields indicate that excitation can be characterized by two driving functions: one due to field gradients and the other due to fields at the boundaries of neuronal structures. It is found that boundary field driving functions play an important role in governing excitation char acteristics during magnetic stimulation. Simulations indicate that axo ns whose lengths are short compared to the spatial extent of the induc ed held are easier to excite than longer axons of the same diameter. S imulations also indicate that independent cellular dendritic processes are probably not excited during magnetic stimulation. Analysis of the temporal distribution of induced fields indicates that the temporal s hape of the stimulus waveform modulates excitation thresholds and prop agation of action potentials.