Figure 4.

PD neurons retain adaptation to high potassium saline even after several hours of wash in control saline

(A) Four-second segments of a PD neuron’s activity in control physiological saline (i), and at 15 min into the first (ii), second (iii), third (iv), and fourth (v) applications of 2.5x[K⁺] saline, and upon the final wash in control saline (vi).

(B) Voltage trace for the same PD neuron over the entire experiment. Green shaded boxes indicate time of 2.5x[K⁺] saline superfusion. Below this trace is shown a raster plot of spiking activity for each of the four applications of 2.5x[K⁺] saline, with bursting activity plotted in a darker shade and tonic firing plotted in a lighter shade.

(C and D) Raster plots of spiking activity in 2.5x[K⁺] saline for six PD neurons (15–20) exposed to the same four repeated exposures. For all plots, bursting activity is plotted in a darker shade and tonic firing in a lighter shade. The top raster (15) is the same animal as that shown in (A) and (B) above. (D) Latency to recovery of the first action potential for each PD neuron across all high [K⁺] applications. The time of silence in the first application is significantly higher than the third (∗∗p = 0.0043) and fourth applications (∗∗p = 0.0022).

(E and F) Average PD spikes per minute for all four applications are plotted in the dark line, with ±SEM lighter shaded regions around them. (F) Average PD dip value for all three applications is plotted in the dark line, with ±SEM lighter shaded regions around the lines.