Fig. 3.

Short-term plasticity measured at frog (A–C) and mouse (D–F) NMJs. A: plot of the changes in paired-pulse ratio (EPP2/EPP1) at the frog NMJ when 2 stimuli were delivered at varying interstimulus intervals (10–100 ms). Paired-pulse facilitation is very sensitive to interstimulus interval at the frog NMJ. B: plot of tetanic potentiation, normalized to the amplitude of the first EPP (EPPx/EPP1), when 5 stimuli were delivered to the frog motor nerve at varying frequencies (10–100 Hz). Data plotted in black were collected at room temperature (20–22°C); data plotted in blue were recorded at 10–12°C. The magnitude of tetanic potentiation is very sensitive to stimulus frequency at the frog NMJ. C: sample EPPs recorded from a frog NMJ during a 100-Hz stimulus train at 20–22°C (black) and 10–12°C (blue). D: plot of the changes in paired-pulse ratio (EPP2/EPP1) at the mouse NMJ when 2 stimuli were delivered at varying interstimulus intervals (10–100 ms). Paired-pulse facilitation is minimal and relatively insensitive to interstimulus interval at the mouse NMJ. E: plot of tetanic potentiation, normalized to the amplitude of the first EPP (EPPx/EPP1), when 5 stimuli were delivered to the mouse motor nerve at varying frequencies (10–100 Hz). Data plotted in black were collected at room temperature (20–22°C); data plotted in red were recorded at 30–32°C. At the mouse NMJ, mild tetanic potentiation gives way to mild depression at room temperature, and this form of short-term plasticity is relatively insensitive to stimulus frequency. Mild depression persists even at warmer temperatures (30–32°C). F: sample EPPs recorded from a mouse neuromuscular junction during a 100-Hz stimulus train at 20–22°C (black) and 30–32°C (red).