FIG. 2.

Current reaching the cell body and number of active L-type Ca²⁺ channel hot spots for 3 motoneuron models with 4 distributions of inhibitory synapses activated at various frequencies and an R_m of 5,000 Ω·cm². The cell body was clamped at −55 mV and excitatory synaptic inputs were activated at 50 Hz. Current reaching the cell body for LAD5-4 (A), LVN2-1 (B), and LVN4-1 (C). Solid lines indicate simulations with L-type Ca²⁺ channels distributed in hot spots. Dashed lines indicate simulations with no L-type Ca²⁺ channels present. D–F: number of active L-type Ca²⁺ channel hot spots for LAD5-4 (D), LVN2-1 (E), and LVN4-1 (F). A hot spot is defined as active if the open probability of its channels is >0.5. Dotted lines indicate the total number of L-type Ca²⁺ channel hot spots in each model.