Figure 3: Depolarization broadens the spike-initiation area slowing down local spikes.
From: Neuronal adaptation involves rapid expansion of the action potential initiation site
(a) Characteristic recordings of somatic (upper trace) and axonal (lower trace, ~\n75 μm from the soma) spikes generated following shorter (black) and longer (grey) subthreshold depolarization periods, as indicated. (b) A summary of changes in the (ta−ts) latency plotted for different recording positions in the axon (compare with Fig. 2f). Dashed lines, linear regression (n=11 at 25 °C, P<0.005; n=12 at 33 °C, P<0.013) suggesting an increase in the expected distance between the axonal AP-initiation site and the soma. (c) Characteristic examples of axonal recordings showing the first (black) and third (red) spikes generated during somatic depolarization (as in Fig. 2c) for a relatively proximal (top) and a relatively distal (bottom) axonal recording site, as indicated. (d) Changes in the amplitude (left panel, n=30) and the rise time (right panel, n=35) of the third compared with the first spike, plotted against the distance from the recording site to the soma. Red lines, best fit single-exponential decay.
