The persistent PTD is unaffected by manipulations of endocannabinoid signaling.

<p><b><b><i>A,</i></b></b> Comparison of the averaged fEPSP/FV changes induced by 4 pulses (n = 35) or 10 pulses (n = 34) of PF stimulation at 200 Hz. <b>B,</b> Persistent PTD amplitude plotted against the SSE amplitude (10 pulses induction; n = 34). <b><i>C,</i></b> Prolongation of SSE in 1 µM JZL184. When 2 µM AM251 is added to JZL184, the remaining persistent PTD is undistinguishable from persistent PTD in AM251 alone (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0070277#pone-0070277-g001" target="_blank">Fig. 1H</a>). <b><i>D,</i></b> Average persistent PTD amplitude in 2 µM AM251 (n = 13), 1 µM JZL184 and 2 µM AM251 (n = 12), 5 µM anandamide (n = 6), 10 µM capsazepine (n = 5).