Figure 5.

Cross talk between NMDA-eEPSCs and NMDA-mEPSCs in autaptic cultures. A–E, Quantification of the effect of blocking NMDA-mEPSCs with MK-801 on subsequent evoked NMDA-eEPSCs (n = 6). A, B, NMDA-eEPSCs and mEPSCs were recorded before a 20 min incubation in 5 μm MK-801 and 500 nm TTX. At the end of the 20 min period, MK-801 was washed out and NMDA-eEPSCs and mEPSCs were recorded again. C, Twenty minutes in MK-801 was sufficient to eliminate almost all spontaneous NMDA-mEPSCs. D, In contrast, the decrease in evoked NMDA-eEPSC peak amplitudes was not a statistically significant (p > 0.37). E, The percentage of reduction in NMDA-mEPSCs was significantly higher than the decrease in NMDA-eEPSCs (**p < 0.01). The bar shows the mean percentage of reduction calculated by averaging reduction percentages from individual experiments. F–J, Quantification of the effect of MK-801 block of NMDA-eEPSCs on subsequent NMDA-mEPSCs (n = 8). F, G, mEPSCs were recorded for 1 min, just before a 30 stimuli train at 3 Hz in the presence of MK-801. After the train, MK-801 was washed out for 1 min, and then another evoked NMDA-eEPSC was recorded, followed by the recording of NMDA-mEPSCs for another minute. H, Under these conditions, NMDA-mEPSCs were decreased by 24.2 ± 4.4% (*p < 0.05). I, In contrast, the decrease in NMDA-eEPSCs was 50.6 ± 7.2%. J, The percentage of decrease in NMDA-eEPSCs was significantly higher than the reduction in NMDA-mEPSCs (*p < 0.05).