FIGURE 8.

Asymmetric propagation of dendritic plateau potential. (A) Schematic drawing of a spiny basal dendrite. Red dots denote glutamatergic afferents actively releasing glutamate at this moment of time. (B) Voltage waveform of the glutamate-induced plateau potential simultaneously viewed at seven different sites along the spiny dendrite (Milojkovic et al., 2004, 2005a, 2007). (C) The amplitude of the slow component (plateau phase) attenuates as dendritic potential spreads passively toward the cell body (centripetal direction, Milojkovic et al., 2004; their Figures 3 and 4). However, the duration remains the same across the entire dendritic branch. The grade of attenuation is less in centrifugal direction (from the initiation site toward the dendritic tip) than in the centripetal direction. Regardless of direction (centripetal or centrifugal), the propagating plateau potentials successively open voltage-gated Ca²⁺ channels in dendritic segments, which explains why the entire dendritic branch experiences significant calcium influx during a glutamate-evoked dendritic plateau potential (even though synaptic glutamate receptor channels are activated at the input site only). This interplay between dendritic membrane potential and dendritic calcium influx in space and time was revealed by combining voltage-sensitive and calcium-sensitive multi-site recordings along the same dendritic branch (Milojkovic et al., 2007).