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. Author manuscript; available in PMC: 2011 Jul 1.
Published in final edited form as: Neuropsychologia. 2010 Apr 27;48(8):2357–2369. doi: 10.1016/j.neuropsychologia.2010.04.015

Figure 1.

Figure 1

Evidence from our laboratory that complete HPC damage in rats has dissociable effects on anterograde and retrograde memory in contextual fear conditioning. Complete damage made to the HPC before a single contextual fear conditioning session (Anterograde) did not cause anterograde amnesia, suggesting that, in absence of the HPC, non-HPC memory systems can readily acquire and support the memory for successful performance on the retention test. However, complete HPC damage induced 1–3 days after a single contextual fear conditioning session (Retrograde) almost abolished freezing during the retention test, suggesting profound retrograde amnesia and that contextual fear conditioning is normally dependent on the HPC. That contextual fear conditioning is normally dependent on the HPC, but can be supported by non-HPC memory systems in absence of the HPC implies that in the intact brain the HPC and non-HPC systems interact and that the HPC overshadows or prevents the non-HPC systems from acquiring an independent memory.