Periodic Reporting for period 1 - METHA (Functional interaction between a prefrontal and a thalamic nucleus for the consolidation of spatial memories)
Période du rapport: 2020-04-01 au 2022-03-31
Then our overall objective was to study RSC to LD projections, a previously unexplored neural pathway for the recall of memory, and also to better describe the function of the Laterodorsal Thalamus and its contribution to spatial navigation and memory.
To study the kind of information the LD – RSC is processing, we also visualized and recorded the activity of neurons from both nuclei in mice performing contextual fear conditioning. We managed to extract data from hundreds of individual neurons and we implemented in-house analysis pipelines to find head direction cells. For this objective we also introduced a variation in the behavioral paradigm: we train mice in one context as mentioned above and assess the memory at recent (1 day after training) and remote (21 days) in the same context (A), but also in a different one (B). By doing this we found that, at recent recall, mice do freeze much more in context A, in which they were trained, and significantly less in the context B; Conversely, at a remote time point, mice do freeze to the same level in both contexts. This suggests there is a strong generalization effect over time. Furthermore, preliminary analysis show there is a portion of mice able to distinguish between contexts (“discriminators”), while other cannot (“generalizers”). The latter opens the opportunity to compare neuronal activity also between these two populations.
Preliminary results of these tasks as well as proofs of progress had been presented at internal seminars and scientific meetings. A more complete set of results is expected to be presented in a poster at Neuroscience Annual Meeting in November this year.
To our knowledge, only a few articles had shown the presence of head direction cells in the Laterodorsal Thalamus of the rodent brain, describing just a few neurons per animal. We can now better characterize its neuronal activity at both, single cell and population level, since we visualized and recorded the activity of hundreds of cells from the LD of freely behaving mice subjected to training, consolidation and recall of contextual fear memory. Furthermore, the miniscope technique we used, allow us to track the activity of neurons over time. Our findings will have an impact in the memory and spatial navigation field, opening new ways in the study of basic mechanisms involved in pathologies like post-traumatic stress disorder and dementia.