Figure 8. Recordings of 12 consecutive fiber volleys separated by interpulse intervals of 30 ms (A) demonstrating a use-dependent decrease in amplitude produced by riluzole (2.0 micro Meter). The lower four traces (B) are expanded views of the first and last fiber volley in a train, highlighting the greater decrease in FV amplitude produced by riluzole on the last response compared with control. A graph of fiber volley amplitudes versus experimental time (C) shows the slow onset and recovery times after a 20-min application of riluzole. Later responses in the train were depressed sooner, but required more time for recovery, compared with early fiber volleys. Only responses to the first, fourth, eighth, and twelfth stimulus in each train were plotted. Values are expressed as a percent of control fiber volley amplitudes.