Fig. 5.

Changes in Ca²⁺ occur during LTFE induction but do not persist with LTFE maintenance. Averages of simultaneous recordings of the increases in the PMn firing frequency (Hz, in black) and the increases in fluorescence of the calcium-binding dye OGB-1 (ΔF/F, in gray) in response to frequency that pulse stimuli are delivered. Lightly shaded areas around the average represent SE and black bars below the trace denote afferent fiber stimulation. A: mild LTFE induction (100 pulses: 100 Hz, 1 s, n = 9). B: moderate LTFE induction (300 pulses: 3 × 100 Hz, 1 s each, n = 7). C: robust LTFE induction (4,000 pulses: 5 Hz for 800 s, n = 4).