The Neural Mechanisms Underlying Trace Auditory Fear Conditioning Depends on the Length of the Trace Interval

Abstract

Event Abstract Back to Event The Neural Mechanisms Underlying Trace Auditory Fear Conditioning Depends on the Length of the Trace Interval Marta Guimarais1*, N. Guyon1 and Marta Moita1 1 Instituto Gulbenkian de Ciencia/ Fundacao Champalimaud, Portugal During trace auditory fear conditioning (tAFC) animals learn to fear a tone that is followed by a footshock. The mechanisms underlying the association between a tone and shock, that occur separate in time, remain elusive. Several studies have shown that the hippocampus is required for the acquisition of the tone-shock association only when the two stimuli are separate in time. Due to its role in spatial and episodic memory, it is possible that the hippocampus contributes to tAFC by linking events, tone and shock, to the spatial context in which they occur. In addition, it has been shown that tAFC requires an intact medial prefrontal cortex (mPFC) raising the possibility that this association could be acquired using working memory, which maintains a memory of the tone until the shock is delivered. We believe that both episodic and working like memory maybe used during tAFC, engaging respectively the hippocampus and the mPFC. Furthermore, as a previous study showed that the hippocampus is involved in the tFC acquisition only when the tone and shock are separated by longer intervals (more than 10 seconds), we hypothesized that the length of the temporal gap between the two stimuli may influence which strategy, working or episodic memory, will predominate in the learning of the tone-sock association. We set out to test this hypothesis, first by confirming this previous finding. We performed pre-training inactivation of the hippocampus in rats using muscimol or PBS as a control. After the infusion all rats where trained with a single tone-shock pairing using either a 5s or a 40s trace interval at the end of which footshock was delivered. We found that hippocampal inactivation disrupted the acquisition of the tone-shock association when 40s, but not 5s, were used as trace interval.According to our hypothesis the animals could employ a different learning strategy during learning of tAFC paradigm depending on the length of the trace interval. As the hippocampus is engaged only when a longer interval is used, and because the mPFC is involved in this form of learning (see above), it is possible that a short interval between tone and shock requires the mPFC because a working memory like strategy is being use to form tone-shock association. Consequently inactivating this structure should impair tAFC learning when a short trace interval (5s) is used. To test this, animals were divided in two groups, one receiving pre-training muscimol infusion and the other PBS as a control. After infusion, both groups were training using a single tAFC tone-shock pairing protocol with a 5s trace interval. As expected, pre-training mPFC muscimol inactivation significantly impairs the learning of tone-shock association in aTFC when using a short trace interval (5s).In conclusion, our results show that the length of the interval between tone and shock determines which structures are required for learning their association. Conference: 11th Meeting of the Portuguese Society for Neuroscience, Braga, Portugal, 4 Jun - 6 Jun, 2009. Presentation Type: Poster Presentation Citation: Guimarais M, Guyon N and Moita M (2009). The Neural Mechanisms Underlying Trace Auditory Fear Conditioning Depends on the Length of the Trace Interval. Front. Neurosci. Conference Abstract: 11th Meeting of the Portuguese Society for Neuroscience. doi: 10.3389/conf.neuro.01.2009.11.122 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 11 Aug 2009; Published Online: 11 Aug 2009. * Correspondence: Marta Guimarais, Instituto Gulbenkian de Ciencia/ Fundacao Champalimaud, Oeiras, Portugal, nemoABS01@frontiersin.org Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Marta Guimarais N. Guyon Marta Moita Google Marta Guimarais N. Guyon Marta Moita Google Scholar Marta Guimarais N. Guyon Marta Moita PubMed Marta Guimarais N. Guyon Marta Moita Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.