Models of Neocortical Layer 5b Pyramidal Cells Capturing a Wide Range of Dendritic and Perisomatic Active Properties
A. The dually-constrained model neuron shown in Figure 4 was stimulated at the soma with a train of five brief suprathreshold depolarizing pulses, resulting in a train of somatic Na+ APs (black). Left, five somatic APs at 70 Hz did not elicit a Ca2+ spike in the dendrites whereas at 120 Hz (right) a regenerative Ca2+ spike was generated in the dendrites (red trace denotes dendritic voltage, measured at 830 µm from soma). B. Peak voltage response in the apical dendritic “hot” zone (830 µm from soma) as a function of the frequency of the somatic train of five APs. At a “critical frequency” around 100 Hz an “all or none” Ca2+ spike was generated at the dendrites.