Figure 4.

LFS-induced LTD in visual cortex by mGluR2. (A) LTD by LFS (900 pulses, 1 Hz) blocked by d-APV (50 μM, seven slices, five WT mice). (B) Robust LTD by DCG-IV (1 μM, 20 min) in d-APV (50 μM, 10 slices, five WT mice). (C) LTD by LFS in WT (six slices, three mice) blocked by mGluR2 antagonist, MCCG (100 μM, left), reversibly (>40-min wash, right). (D) No LTD by LFS in mGluR2 KO (●, 10 slices, four mice) vs. WT (○, nine slices, four mice). (E) Weak, decaying depression by LFS when NMDA receptor function is enhanced (50:1 Ca²⁺/Mg²⁺ ratio, 10 μM d-cycloserine) in mGluR2 KO (○, five slices, three mice). Further group I mGluR blockade unmasks potentiation by LFS (●, 500 μM AIDA; four slices, two mice).