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From "hippocampal" to "cortical" functions: insights from the thalamus| old_uid | 14766 |
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| title | From "hippocampal" to "cortical" functions: insights from the thalamus |
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| start_date | 2014/12/05 |
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| schedule | 12h15 |
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| online | no |
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| location_info | Bât. 4R3 |
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| summary | Today, the idea that the integrity of the limbic thalamus is necessary for normal memory functions is well established. In particular, the anterior thalamus provides critical support for the so-called “hippocampal” functions, be they spatial or nonspatial. This unique role played by the anterior thalamus results from its connectivity within the Papez circuit but also from specific neurophysiological features that differ from that of the hippocampus proper. Due to the widespread diencephalic lesions that produce amnesia in thalamic patients, the functional contribution of the anterior thalamus has often been contrasted with that of the mediodorsal thalamus. We employed tract-tracing techniques to provide a better understanding on specific thalamocortical pathways originating from this latter region. By doing so, we unexpectedly discovered massive thalamic afferents to the orbitofrontal cortex provided by a small thalamic area, the submedius, whose functions are currently mostly unknown. We then compared the effect of submedius versus orbitofrontal lesions in behaving rats performing a set of tasks assessing various aspects of Pavlovian learning. The results indicate that the submedius support at least some of the functions classically attributed to the orbitofrontal cortex, namely the ability to update Pavlovian contingencies. Altogether, the data support the view that the limbic thalamus is functionally highly heterogeneous and that specific thalamocortical loops may share the same anatomical organization while supporting dissociable functions. |
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| responsibles | Devaud |
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