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Subregion-specific differences in hippocampal activity between Delay and Trace fear conditioning: an
Adam Z Weitemier1, Andrey E Ryabinin
1Department of Behavioral Neuroscience, L470, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA. weitemie@ohsu.edu
Brain Research
|December 4, 2003
Summary
Hippocampal subregions show distinct neural activation patterns during the acquisition and retrieval of Delay versus Trace fear conditioning in mice. This highlights differential roles of these brain areas in distinct fear memory processes.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Neurobiology
Background:
- The hippocampus plays a critical role in fear conditioning.
- Previous research indicates that hippocampal lesions impair Trace fear conditioning but not Delay fear conditioning.
- This suggests differential involvement of hippocampal regions in these two forms of fear memory.
Purpose of the Study:
- To investigate the hypothesis of differential neuronal activation in hippocampal subregions during acquisition and retrieval of Delay and Trace fear conditioning.
- To compare the expression of inducible transcription factors (ITFs) c-Fos and Zif268 in various brain regions between Delay and Trace fear conditioning paradigms.
Main Methods:
- Male C57BL/6J mice underwent Delay or Trace fear conditioning with eight tone-shock pairings.
- Brain tissue from ten regions was analyzed for c-Fos and Zif268 expression using immunohistochemistry 1.5 hours post-training or post-testing.
- Behavioral testing involved assessing immobility upon reexposure to contextual stimuli or tone cues.
Main Results:
- Both Delay and Trace conditioning increased c-Fos expression in most analyzed brain regions compared to controls.
- Delay conditioning led to higher c-Fos induction in the hippocampal CA3 region than Trace conditioning.
- Trace conditioning resulted in higher Zif268 levels in the dentate gyrus post-cue reexposure compared to Delay conditioning.
- Anterior cingulate cortex showed higher c-Fos expression during reexposure in Delay-conditioned versus Trace-conditioned animals.
Conclusions:
- The study confirms differential activation of hippocampal subregions during Delay and Trace fear conditioning.
- Specific hippocampal areas, like CA3 and dentate gyrus, are differentially involved in the acquisition and retrieval phases of these conditioning types.
- Findings support distinct neural mechanisms underlying different forms of fear memory processing.