Figure 4. Coincidence‐detection capability of pyramidal cells.

A, whole‐cell recording from the same pyramidal cell with three independent pipettes. Pipette tips are located at the soma and at the proximal [layer (L)4] and distal portions (L1/2) of the apical dendrite. B, whole‐cell voltage recording from the soma (black), proximal apical dendrite (blue) and distal apical dendrite (red). Upper panel shows time courses of the somatic (black) proximal (blue) and distal (red) dendritic membrane potential during stimulation by current injection into the distal apical dendrite (I _stim). Middle panel shows somatic (black) and back‐propagating dendritic AP (red, distal and blue, proximal recording) in response to current injection into the soma (I _stim). Lower panel shows that a burst of three somatic APs is evoked by combined somatic and dendritic current injection applied within a short time window (<50 ms; Δt). Time courses of somatic and dendritic current injections are shown below the voltage traces. Adapted from Larkum et al. (1999 b).