Figure 11.

The apical dendrite of ACC pyramidal neurons does not generate Ca²⁺ spikes. A, Left, Neurolucida reconstruction of an L5 pyramidal neuron in the ACC. Positions of recording electrodes are indicated. Middle, EPSP-like current injections (τ_rise = 4 ms, τ_decay = 16 ms) with increasing amplitude-evoked somatic APs above a certain threshold that backpropagate to the dendritic (Dend) recording site, but no plateau potentials that would be indicative of a dendritic Ca²⁺ spike were observed. Somatic traces are shown in black, dendritic traces in blue. Right, Steady-state current injections with increasing amplitude resulted in a regular discharge of somatic APs. Again, no plateau potentials were observed. B, Left, Neurolucida reconstruction of an L5 pyramidal neuron in S1. Positions of recording electrodes are indicated. Middle, EPSP-like current injections with increasing amplitude evoked a sudden dendritic Ca²⁺ spike that triggered somatic APs. Somatic traces are shown in black, dendritic traces are in green. Right, Steady-state current injections with increasing amplitude resulted in a sudden occurrence of a dendritic plateau potential that triggered bursts of somatic APs.