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Identifier 000460746
Title Neurophysiological alternations in the hippocampus after working memory training
Alternative Title Νευροφυσιολογικές αλλαγές στον ιππόκαμπο μετά από εκπαίδευση της μνήμης εργασίας
Author Δρακάκη, Ζωή
Thesis advisor Σιδηροπούλου, Κυριακή
Reviewer Γιακουμάκη, Στέλλα
Φρουδαράκης, Εμμανουήλ
Abstract Working Memory (WM) is the ability to store and adaptively handle information in a timescale of seconds, in order to plan and execute complex cognitive tasks Besides the prefrontal cortex (PFC) which has a pronounced role in this process, hippocampus also has a pivotal role -especially in spatial WM. Although the neural correlates of WM have been extensively researched, the neurobiological effects of WM training remain largely unknown. Previous work from the lab has shown that WM training in male mice improves cognitive flexibility and enhances long-term potentiation (LTP) as well as dendritic spine density in the PFC. On the other hand, WM training in female mice did not affect cognitive flexibility or the LTP and dendritic spine density in the PFC. However, it enhanced both LTP and dendritic spine density in the hippocampus. Therefore, this study aimed to extend the above results by investigating the effects of WM training in female mice in anxiety, WM reference memory as well as the properties of spontaneous activity immediately following the training. Furthermore, the study investigated the duration of the LTP enhancement in the hippocampus. Adult female mice were separated in two training groups: one that was trained in the delayed alternation task (adaptive) and the other that was trained in the alternation procedure (non-adaptive) for 6 days. The effects of training on anxiety levels, using the open-field and light dark test, on working memory and on reference memory and reversal learning, using the left-right discrimination task and reversal were measured. Both groups showed reduced anxiety levels in the light-dark test following training, compared to before training. In the working memory test, the adaptive groups performed better compared to the non-adaptive group. In the left-right discrimination task, there was no difference in the performance following training, compared to before, but mice performed the task with reduced latency. In the reversal learning, both behavioral groups performed with higher accuracy and latency post-training. Following the behavioral testing, the mice brains were harvested for electrophysiological recordings, either immediately to study the properties of the spontaneous activity or 2 weeks later to investigate LTP. To study the properties of spontaneous activity, field potential recordings were taken from the three different subregions of the hippocampus, namely CA1, CA3 and dentate gyrus (DG). Our results showed elevated spontaneous spiking activity and oscillatory power in the hippocampus. Finally, the effects of training on synaptic plasticity were observed 14 days after training, when field excitatory post-synaptic potential recordings were obtained in the CA1 region of the hippocampus. Both groups had enhanced long-term potentiation compared to naive controls. Taken together, these results suggest that working memory training leads to cognitive flexibility and enhances oscillation power as well as long-lasting synaptic plasticity in HPC.
Language English
Subject Cognitive flexibility
Long term potentiation
Spontaneous activity
Γνωστική ευεληξία
Μακρόχρονη ενδυνάμωση
Πλαστικότητα
Issue date 2023-12-08
Collection   School/Department--School of Medicine--Department of Medicine--Post-graduate theses
  Type of Work--Post-graduate theses
Permanent Link https://elocus.lib.uoc.gr//dlib/b/5/d/metadata-dlib-1701337408-263214-7847.tkl Bookmark and Share
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