Article

Hippocampus and contextual fear conditioning: Recent controversies and advances

Department of Psychology and Brain Research Institute, University of California, Los Angeles 90095-1563, USA.
Hippocampus (Impact Factor: 4.3). 01/2001; 11(1):8-17. DOI: 10.1002/1098-1063(2001)11:1<8::AID-HIPO1015>3.0.CO;2-7
Source: PubMed

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.

Full-text

Available from: Stephan G Anagnostaras, Apr 18, 2015
1 Follower
 · 
201 Views
  • Source
  • Source
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A bulk of evidence currently suggests that hippocampal formation is a heterogeneous brain structure. Most recent studies recognize a hippocampal pole (dorsal/septal or posterior in humans) which is primarily related with memory and learning processes, and another one (ventral/temporal or anterior in humans) which is linked with anxiety, affective or emotional processes. An intermediate region separating the two poles appears to have overlapping characteristics with its neighbors. The present chapter summarizes previously reported differences between septal and temporal dentate gyrus, a key component of the hippocampal circuitry, and provides new information on the segmental variation of the dentate gyrus. Data on the cellular (neuronal and glial) composition of the dentate gyrus are linked with the diverged embryonic origin and continuous cell generation capacity of the septal and temporal poles, septo-temporal molecular/genomic patterns are correlated with trends reported by connectivity (tracing) studies, and distinct characteristics of the two poles in the healthy and the diseased brain are examined together with their peculiar neurochemical and vascularization patterns in order to i. provide an explanatory framework for the understanding of the segmental hippocampal functional and behavioral specialization, and ii. highlight the need for thorough and detailed knowledge of all possible parameters which may allow unlocking of the hippocampal dysfunction. No part of this digital document may be reproduced, stored in a retrieval system or transmitted commercially in any form or by any means. The publisher has taken reasonable care in the preparation of this digital document, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained herein. This digital document is sold with the clear understanding that the publisher is not engaged in rendering legal, medical or any other professional services.
    Dentate Gyrus, Edited by Zackery Lowes, 01/2015: chapter 5: pages 137-198; Nova Science Publishers Inc.., ISBN: 978-1-63463-371-0