Figure 12.

Compartmentalization of the distal apical tuft of a neocortical pyramidal cell. Left column: Two different distal branches were stimulated (electrodes 1 and 2) while recordings were made from two more proximal sites (black electrodes 1 and 2). Stimulation at site 1 evoked a series of EPSPs (middle column, top), while stimulation at site 2 evoked NMDA spikes (middle column, middle). Simultaneous stimulation gave supralinear summation to produce a Ca²⁺ spike at the Ca²⁺ spike initiation zone in the apical dendrite (middle column, bottom). Right column: summary diagram of relation between NMDA spike generating distal branches and Ca²⁺ and Na²⁺ spike generating proximal sites. From Larkum et al. (2009).