Figure 3.
Acquisition and extinction of context-dependent fear involve actin rearrangement. A, Cytochalasin D and latrunculin A (125 ng each per hippocampus) injected intrahippocampally immediately after training prevented the consolidation of context-dependent fear. B, Representative immunoblots demonstrating the biochemical effects of the inhibitors injected intrahippocampally immediately after training. The inhibitors did not affect the production of the cFos protein or the phosphorylation of cJun and ATF2 in hippocampal lysates prepared 1 hr after training. The experiment was replicated twice with three mice per group. C, The same doses of cytochalasin D and latrunculin A injected intrahippocampally after each nonreinforced memory test prevented the extinction of context-dependent freezing (compared with the vehicle group). D, Cytochalasin D and latrunculin A injected intrahippocampally after extinction did not result in increased conditioned freezing. Statistical differences: *p < 0.01, **p < 0.01 versus vehicle control; ap < 0.01 versus test 1.