TBS CA1 LTP is normal in Arc^fl/fl animals. A, There was no significant difference in basal synaptic transmission between Arc^fl/fl animals injected with GFP and GFP-Cre-injected animals. B, There was no significant difference in the magnitude of LTP over the first 5 min poststimulation, nor over the last 5 min of recording, between Arc^fl/fl animals injected with GFP-cre and those injected with GFP alone when LTP was induced using a theta-burst stimulation protocol (4 trains at 10 s intertrain intervals; each train consisted of 10 bursts at 5 Hz, with each burst containing 4 stimuli at 100 Hz). Data are represented as mean ± SEM. Scale bars: 0.5 mV (horizontal) and 5 ms (vertical). C, Arc protein expression was significantly reduced in Arc^fl/fl animals injected with GFP-cre (green circles) compared with GFP alone (black circles). Inset, Representative image of GFP expression (green is GFP, blue is DAPI), 2 weeks postinjection of AAV:CaMKII-GFP-cre into the CA1 region of the hippocampus. Scale bar, 500 µm.