Bursting Activity in Weakly Electric Fish - Computational Neuroscience: A Comprehensive Approach - page 231

Figure 8.9
Summary of the mechanism underlying high-frequency burst generation in pyrami-
dal cells in vitro . a) Schematic diagram of a pyramidal cell with a narrow spike
recorded in the soma (1). The somatic spike is actively propagated back into the
apical dendrite where a much broader version of the same spike can be recorded
(2). Current sourcing from the dendrite back into the soma causes a DAP (3). b)
Top: Oscillatory burst discharge recorded in the soma of a pyramidal cell with 0.74
nA depolarizing current injection. Middle and bottom: Somatic and dendritic spike
burst recorded separately in two different cells. The time scales are adjusted to allow
alignment of spikes. Somatic spikes are truncated. As evident from the dendritic
recording, spike repolarization slows down in the course of a burst allowing the DAP
at the soma to potentiate. Eventually, the DAP reaches threshold and causes a high-
frequency spike doublet. Since the dendritic refractory period is longer than the
somatic one, the dendrite cannot support active propagation of the second spike of
the doublet. The DAP fails and allows the afterhyperpolarization (AHP) to terminate
the spike burst. (a) adapted from [75], (b) adapted from [34].