Hippocampus and contextual fear conditioning: recent controversies and advances

SG Anagnostaras, GD Gale, MS Fanselow - Hippocampus, 2001 - Wiley Online Library
Hippocampus, 2001Wiley Online Library
Dorsal hippocampal (DH) lesions produce a severe deficit in recently, but not remotely,
acquired contextual fear without impairing memory of discrete training stimuli, ie, DH lesions
produce an anterograde and time‐limited retrograde amnesia specific to contextual memory.
These data are consistent with the standard model which posits temporary involvement of
the hippocampus in recent memory maintenance. However, three recent controversies
apparently weaken the case for a selective mnemonic role for the hippocampus in …
Abstract
Dorsal hippocampal (DH) lesions produce a severe deficit in recently, but not remotely, acquired contextual fear without impairing memory of discrete training stimuli, i.e., DH lesions produce an anterograde and time‐limited retrograde amnesia specific to contextual memory. These data are consistent with the standard model which posits temporary involvement of the hippocampus in recent memory maintenance. However, three recent controversies apparently weaken the case for a selective mnemonic role for the hippocampus in contextual fear. First, although retrograde amnesia (from posttraining lesions) is severe, anterograde amnesia (from pretraining lesions) may be mild or nonexistent. Second, a performance, rather than mnemonic, account of contextual freezing deficits in hippocampal‐lesioned animals has been offered. Third, damage to the entire hippocampus, including the ventral hippocampus, can produce a dramatic and temporally stable disruption of context and tone fear. These data are reviewed and explanations are offered as to why they do not necessarily challenge the standard model of hippocampal memory function in contextual fear. Finally, a more complete description of the hippocampus' proposed role in contextual fear is offered, along with new data supporting this view. In summary, the data support a specific mnemonic role for the DH in the acquisition and consolidation of contextual representations. Hippocampus 2001;11:8–17. © 2001 Wiley‐Liss, Inc.
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