Locational influence of dendritic PIC on input-output properties of spinal motoneurons (Kim 2017)
How does the dendritic location of calcium persistent inward current (Ca-PIC) influence dendritic excitability and firing behavior across the spinal motoneuron pool? This issue was investigated developing a model motoneuron pool where model parameters were analytically determined to reflect key motoneuron type-specific properties experimentally identified. The simulation results point out the negative relationship between the distance of Ca-PIC source from the soma and cell recruitment threshold as a basis underlying the systematic variation in input-output properties of motoneurons over the motoneuron pool.
Readme for the simulations associated with: Hojeong Kim, Impact of the localization of dendritic calcium persistent inward current on the input-output properties of spinal motoneuron pool: a computational study, J App Physiol 123(5):1166-1187, 2017. The goal of this study is to investigate how the dendritic Ca-PIC location influences nonlinear input-output properties and depends on the type of motoneurons across the motoneuron pool. A model motoneuron pool consisting of 10 motoneurons was constructed using a recently developed two-compartment modeling approach that reflected key cell type-associated properties experimentally identified. The dendritic excitability and firing output depended systematically on both the PIC location and the motoneuron type. The PIC onset and offset in the current-voltage (I-V) relationship tended to occur at more hyperpolarized voltages as the path length to the PIC channels from the soma increased and as the cell type shifted from high- to low-threshold motoneurons. At the same time, the firing acceleration and frequency hysteresis in the frequency-current (F-I) relationship became faster and larger, respectively. However, the PIC onset-offset hysteresis increased as the path length and the recruitment threshold increased. Furthermore, the gain of frequency-current function before full PIC activation was larger for PIC channels located over distal dendritic regions in low- compared with high-threshold motoneurons. When compared with previously published experimental observations, the modeling concurred when Ca-PIC channels were placed closer to the soma in high- than low-threshold motoneurons in the model motoneuron pool. All of these results suggest that the negative relationship of Ca-PIC location and cell recruitment threshold may underlie the systematic variation in I-V and F-I transformation across the motoneuron pool. The direct comparison between the anatomical and reduced motoneuron model has been made for FR-type alpha-motoneuron while varying the distance (i.e., Dpath) to the dendritic site of Ca-PIC from the soma in our previous study: 2014 PLOS ONE (Kim, Jones and Heckman). The input-output properties of the reduced motoneuron model presented in Figure 3 of the paper can be simulated by running individual ode files for Figure 3 A-D. The input-output properties for other types of reduced motoneurons over various locations of Ca-PIC in the dendrites can be simulated by varying the values of model parameters as specified in Table1.xls. Hojeong Kim Convergence Research Institute **DGIST** Daegu Korea [hojeong.kim03@gmail.com](mailto:hojeong.kim03@gmail.com) USAGE: ------ Run with unix/linux commands like: xppaut fig3a.ode Then selecting InitialConds -> Go will produce an image containing the middle trace in figure 3A in the paper: ![screenshot 1]([binary]) Similarly, fig3b.ode, fig3c.ode, fig3d produce: ![screenshot 2]([binary]) ![screenshot 3]([binary]) ![screenshot 4]([binary])
Neuron or other electrically excitable cell
Spinal cord lumbar motor neuron alpha ACh cell
Hojeong Kim. Impact of the localization of dendritic calcium persistent inward current on the input-output properties of spinal motoneuron pool: a computational study. Journal of Applied Physiology 123, 5: 1166-1187 (2017).
Hojeong Kim, Kelvin E. Jones & C. J. Heckman. Asymmetry in signal propagation between the soma and dendrites plays a key role in determining dendritic excitability in motoneurons. PLoS ONE 9, 8: e95454 (2014).