Figure 3. Comparison of effects produced by riluzole or thiopental on paired pulse recordings revealed differences in effects on recurrent inhibition. Riluzole produced an equivalent reduction of both population spikes after paired stimulus pulses. Thiopental produced a greater depression of the second population spike, indicating that enhanced gamma-amino butyric acid-mediated inhibition occurred. The bottom traces are expanded views of recordings showing that riluzole decreased the rate of rise for the early positive synaptic response, whereas thiopental did not.