Fig. 2.

Developmental changes in single action potential properties. A, Examples of typical action potentials at P2, P6, and P9 and in the adult. The voltage recordings were shifted vertically to align the action potential thresholds (dashed lines). Note the progressive, age-related increase in amplitude and the concomitant reduction in duration. B–E, Scatter plots showing age-related changes in threshold, amplitude (measured from threshold), duration at threshold, and duration at half-amplitude, respectively. Small open circles represent raw data.Large open circles and bars represent mean ± SEM. Large diamonds represent median values. Note the large scatter of data on the action potential duration at P1–P9. The threshold and amplitude at P1–P3 were significantly different from the adult (p < 0.01 for both), whereas median values of the duration both at threshold and half-amplitude at P1–P3, P5–P7, and P9 were significantly longer than in the adult (p < 0.001, 0.001, and 0.005, respectively).