Strategy for Fitting Neuronal Models to Dual Patch Data under Multiple Stimulation Protocols.

摘要

It is a difficult task to fit a neuronal model to data under multiple stimulation protocols. The protocol of weakest stimulation was used first to fit the model at the initial stage. The strategy of fitting an action potential (AP) consisted of three parts: passive parameter fitting, reduction of spatial complexity, and reduction of temporal complexity. The nearly linear response of a neuron in early depolarization well before AP initiation was used to fit the passive parameters with all the ion channel densities set to zero. The authors separated the fitting of the intervening part between the two electrodes from that beyond the dendritic electrode to reduce the spatial complexity by using dendritic voltage clamp simulation. The decomposition of stimulation protocols and the time course of an AP proved feasible and successful. In this study, 400- micron thick slices were cut from rat olfactory bulbs. Mitral cells and their cell bodies were identified under infrared differential interference contrast microscope. During the recording of whole-cell patch clamp, one electrode was placed on a distal site of the primary dendrite, the other on the somatic region. The dendritic electrode was placed as far from the cell body as possible to obtain as long an inter-electrode distance as possible. There were a total of three cells. Two of them were stimulated with current injection and the other with brief synaptic shocks to the olfactory nerve (ON). The current injection and the synaptic stimulation protocols followed that of previous papers. The four protocols of current injection stimulation included weak and strong stimulation of current injection at the dendritic electrode, and weak and strong stimulation of current injection at the somatic electrode. The intensity of ON shock was controlled at the weak, median, and strong levels, which caused weak, median, and strong excitatory post-synaptic potential (EPSP). (4 figures, 9 refs.).