Is the hippocampus necessary for contextual fear conditioning?

Is the hippocampus necessary for contextual fear conditioning? The hippocampus is widely believed to be essential for learning about the context in which conditioning occurs. This view is based primarily on evidence that lesions of the dorsal hippocampus disrupt freezing to contextual cues after fear conditioning. However, lesions that disrupt freezing produce no effect on fear-potentiated startle, a second measure of contextual fear. Moreover, hippocampal lesions also do not disrupt the contextual ‘blocking’ phenomenon, which provides an indirect measure of contextual fear. In these paradigms, at least, it appears that hippocampal lesions disrupt the expression of freezing, rather than contextual fear itself. This interpretation is supported by the finding that rats showing preserved contextual blocking after hippocampal lesions show deficits not only in contextual freezing, but also in unconditioned freezing. These findings are consistent with a growing body of data from other conditioning paradigms that contextual learning is spared after lesions of the dorsal hippocampus. Nonetheless, there remain some reports of impaired contextual fear conditioning after hippocampal lesions that cannot be attributed easily to a disruption of freezing. Thus, it is concluded that the hippocampus may be involved in contextual learning under certain – as yet, unspecified – circumstances, but is not critical for contextual learning in general. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Behavioural Brain Research Elsevier

Is the hippocampus necessary for contextual fear conditioning?

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Publisher
Elsevier
Copyright
Copyright © 2000 Elsevier Science B.V.
ISSN
0166-4328
DOI
10.1016/S0166-4328(99)00187-4
Publisher site
See Article on Publisher Site

Abstract

The hippocampus is widely believed to be essential for learning about the context in which conditioning occurs. This view is based primarily on evidence that lesions of the dorsal hippocampus disrupt freezing to contextual cues after fear conditioning. However, lesions that disrupt freezing produce no effect on fear-potentiated startle, a second measure of contextual fear. Moreover, hippocampal lesions also do not disrupt the contextual ‘blocking’ phenomenon, which provides an indirect measure of contextual fear. In these paradigms, at least, it appears that hippocampal lesions disrupt the expression of freezing, rather than contextual fear itself. This interpretation is supported by the finding that rats showing preserved contextual blocking after hippocampal lesions show deficits not only in contextual freezing, but also in unconditioned freezing. These findings are consistent with a growing body of data from other conditioning paradigms that contextual learning is spared after lesions of the dorsal hippocampus. Nonetheless, there remain some reports of impaired contextual fear conditioning after hippocampal lesions that cannot be attributed easily to a disruption of freezing. Thus, it is concluded that the hippocampus may be involved in contextual learning under certain – as yet, unspecified – circumstances, but is not critical for contextual learning in general.

Journal

Behavioural Brain ResearchElsevier

Published: Jun 1, 2000

References

  • Discriminative fear conditioning to context expressed by multiple measures of fear in the rat
    Antoniadis, E.A.; McDonald, R.J.
  • Contextual learning and cue association in fear conditioning in mice: a strain comparison and a lesion study
    Gerlai, R.
  • Neurotoxic lesions of the dorsal hippocampus and Pavlovian fear conditioning in rats
    Maren, S.; Aharanov, G.; Fanselow, M.S.
  • Increased sensitivity to the sensorimotor gating-disruptive effects of apomorphine after lesions of medial prefrontal cortex or ventral hippocampus in adults rats
    Swerdlow, N.R.; Lipska, B.K.; Weinberger, D.R.; Braff, D.L.; Jaskiw, G.E.; Geyer, M.A.
  • Hippocampal lesions alter conditioning to conditional and contextual stimuli
    Winocur, G.
  • CREB and the formation of long-term memory
    Yin, J.C.; Tully, T.

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