Fig. 5. Effects of continuous perfusion with NMDA through the microdialysis probe on extracellular Ach (A) and Cho (B) levels in prefrontal cortex: dose–response. Symbols: ▪, control; ▵, NMDA 50 μm; ▿, NMDA 100 μm; ⋄, NMDA 300 μm; ○, NMDA 600 μm. Basal levels (dialysate picomoles per microliter) and number of animals per group (mean ± SEM) were as follows: Ach, ▪, 0.0354 ± 0.0046 (n = 5); ▵, 0.0416 ± 0.0186 (n = 3); ▿, 0.0410 ± 0.0054 (n = 5); ⋄, 0.0509 ± 0.0078 (n = 5); ○, 0.0420 ± 0.0052 (n = 3); Cho, ▪, 1.6503 ± 0.2497 (n = 5); ▵, 2.0743 ± 0.8061 (n = 3); ▿, 1.9570 ± 0.4533 (n = 5); ⋄, 1.4892 ± 0.1027 (n = 5); ○, 0.8294 ± 0.1501 (n = 3). The horizontal barrepresents the period of NMDA perfusion.