Ventral midline thalamus lesion prevents persistence of new (learning-triggered) hippocampal spines, delayed neocortical spinogenesis, and spatial memory durability.
- Autores: Marie Muguet Klein, Thibault Cholvin, Brigitte Cosquer, Aurélie Salvadori, Julia Le Mero, Lola Kourouma, Anne-Laurence Boutillier, Anne Pereira de Vasconcelos, Jean-Christophe Cassel
- Localización: Brain Structure and Function, ISSN 1863-2653, ISSN-e 1863-2661, Vol. 224, Nº. 4, 2019, págs. 1659-1676
- Idioma: inglés
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Resumen
The ventral midline thalamus contributes to hippocampo-cortical interactions supporting systems-level consolidation of memories. Recent hippocampus-dependent memories rely on hippocampal connectivity remodeling. Remote memories are underpinned by neocortical connectivity remodeling. After a ventral midline thalamus lesion, recent spatial memories are formed normally but do not last. Why these memories do not endure after the lesion is unknown. We hypothesized that a lesion could interfere with hippocampal and/or neocortical connectivity remodeling. To test this hypothesis, in a first experiment male rats were subjected to lesion of the reuniens and rhomboid (ReRh) nuclei, trained in a water maze, and tested in a probe trial 5 or 25 days post-acquisition. Dendritic spines were counted in the dorsal hippocampus and medial prefrontal cortex. Spatial learning resulted in a significant increase of mushroom spines in region CA1. This modification persisted between 5 and 25 days post-acquisition in Sham rats, not in rats with ReRh lesion. Furthermore, 25 days after acquisition, the number of mushroom spines in the anterior cingulate cortex (ACC) had undergone a dramatic increase in Sham rats; ReRh lesion prevented this gain. In a second experiment, the increase of c-Fos expression in CA1 accompanying memory retrieval was not affected by the lesion, be it for recent or remote memory. However, in the ACC, the lesion had reduced the retrieval-triggered c-Fos expression observed 25 days post-acquisition. These observations suggest that a ReRh lesion might disrupt spatial remote memory formation by preventing persistence of early remodeled hippocampal connectivity, and spinogenesis in the ACC.;
