The role of the auditory cortex in fear conditioning to complex auditory stimuli

Abstract

Event Abstract Back to Event The role of the auditory cortex in fear conditioning to complex auditory stimuli Simon Rumpel1* 1 Research Institute of Molecular Pathology, Austria Auditory cued fear conditioning (AFC) is a widely used associative learning paradigm in which animals learn to associate a neutral stimulus (CS, conditioned stimulus), usually a pure tone, with an aversive stimulus (US, unconditioned stimulus), e.g. a foot shock. Subsequently, animals show fear-related behaviour when the CS is presented alone. In the amygdala, a putative site of tone-shock association, auditory and sensory input converge onto individual cells and projections from the amygdala to output brain areas, e.g. the brainstem, mediate fear behaviour. Auditory information reaches the amygdala via different pathways, a direct thalamic pathway and a more indirect thalamo-cortical pathway. Interestingly, AFC induces plastic changes in the auditory cortex, as neurons shift their frequency towards that of a pure tone CS. Hence, it is striking that the auditory cortex seems dispensable: AFC is not impaired in animals with a lesioned thalamo-cortical pathway. We probed the role of the auditory cortex in AFC in which the CS was a complex sound. We hypothesized that complex sounds may resemble sounds occurring in natural learning situations more closely than commonly used pure tones. AFC with a complex CS was feasible in wild type mice within one training session and created a robust, long lasting memory: In memory tests one or four days after training mice showed significant freezing levels during CS presentation compared to baseline. Bilateral auditory cortex lesions after training decreased acquired freezing levels to baseline levels, suggesting that the auditory cortex is involved in AFC with complex sounds in the intact brain. Importantly, also pre-training bilateral auditory cortex lesions abolished freezing to the complex CS. Despite these strong effects, lesioned animals could still be retrained to a pure tone CS. This finding demonstrates that the learning deficit following lesions was highly dependent on the features of the CS. AFC with a complex CS was not significantly impaired in mice with unilateral auditory cortex lesions. In a further series of experiments we aimed to elucidate principle features of complex CS that render the auditory cortex necessary for AFC. We used a frequency-modulated pure tone, an amplitude-modulated pure tone or a pseudo chord, which consisted of multiple constant frequencies. We observed that AFC with a pseudo chord showed strongest sensitivity to lesions, indicating that the auditory cortex may play a role in binding of simultaneous auditory information. Our findings emphasize how small changes in the experimental setup can lead to drastic changes in the brain circuits involved. Conference: 41st European Brain and Behaviour Society Meeting, Rhodes Island, Greece, 13 Sep - 18 Sep, 2009. Presentation Type: Oral Presentation Topic: Symposia lectures Citation: Rumpel S (2009). The role of the auditory cortex in fear conditioning to complex auditory stimuli. Conference Abstract: 41st European Brain and Behaviour Society Meeting. doi: 10.3389/conf.neuro.08.2009.09.049 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: 05 Jun 2009; Published Online: 05 Jun 2009. * Correspondence: Simon Rumpel, Research Institute of Molecular Pathology, Vienna, Austria, rumpel@imp.ac.at 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 Simon Rumpel Google Simon Rumpel Google Scholar Simon Rumpel PubMed Simon Rumpel 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.