Wlodkowska, U. | Search bioRxiv

bioRxiv2023

Two complementary circuits for spatial navigation in mouse: evidence from Fos mapping

We designed and implemented a novel spatial behavioral protocol based on the figure 8 maze paradigm. This solution employs a fully automated closed-loop system using visual contexts for guiding behavior. It allows high throughput testing of large cohorts of animals. This automated approach highly reduces the effect of stress, but also eliminates the influence of rule learning and the involvement of working memory. Here, we show that training mice in the apparatus leads to change in strategy from internal tendency to alternate into navigation based exclusively on visual cues. This effect could be achieved using two different protocols: prolonged alternation training, or a flexible protocol with unpredictable turn succession. We provide evidence of opposing levels of engagement of hippocampus and retrosplenial cortex after training mice in these two different regimens. This supports the hypothesis of the existence of parallel circuits supporting navigation, one based on the well described hippocampal representation, and another, RSC-dependent.

neuroscience↗

bioRxiv2023

Spatio-temporal mechanisms of consolidation, recall and reconsolidation in reward-related memory trace

The formation of memories is a complex, multi-scale phenomenon, especially when it involves integration of information from various brain systems. We have investigated the differences between a novel and consolidated association of spatial cues and amphetamine administration, using an in-situ hybridisation method to track the short-term dynamics during the recall testing. We have found that remote recall group involves smaller, but more consolidated groups of neurons, which is consistent with their specialisation. By employing machine learning analysis, we have shown this pattern is especially pronounced in the VTA; furthermore, we also uncovered significant activity patterns in retrosplenial and prefrontal cortices, as well as in the DG and CA3 subfields of the hippocampus. The behavioural propensity towards the associated localisation appears to be driven by the nucleus accumbens, however, further modulated by a trio of the amygdala, VTA and hippocampus, as the trained association is confronted with test experience. These results show that memory mechanisms must be modelled considering individual differences in motivation, as well as covering dynamics of the process.

neuroscience↗