Figure 6.

Glutamate release is elevated close to the electrode during the 100 Hz pattern, but there is also detectable glutamate release during 10 Hz-Burst stimulation. (A) Representative traces from two stimulation trials in two subjects. Subject I2I1 shows strong response during the 100 Hz pattern, but little response during either 10 Hz pattern. Subject I5I1 shows a strong response during Burst stimulation with apparent entrainment during 1 Hz-Bursts. The subject likewise shows some response during 10 Hz-Uniform and 100 Hz patterns. (B) The cumulative dF/F₀ indicates that the strongest glutamate response was for the 100 Hz pattern within 20 μm of the electrode. Two-way ANOVA yielded significant effects for pattern and distance (p < 0.0001) with post-hoc tests indicating a significant increase for the 100 Hz pattern at within 20 μm of the electrode and all other patterns and distances (p < 0.0001). (C) For some subjects, there was strong glutamate entrainment to 10 Hz-Bursting as shown by an elevated 1 Hz power. This was confirmed by a Two-way ANOVA, which showed a statistically significant effect for pattern (p < 0.001). Due to the high variance in the data, there were no significant post-hoc tests. Data in (B) and (C) presented as mean ± SEM. n = 7 trials from a total of 4 subjects.