Ralitsa Todorova

I am interested in the mechanisms of memory consolidation and particularly the role of sleep. I use analysis and data mining to explore coordination between the hippocampal and cortical reactivation events and how these are embedded in the ongoing sleep rhythms to consolidate memories.

In particular, my work concentrates on hippocampal ripples, short events of elevated hippocampal activity in which memory traces of recent experience are ‘replayed’, and how the information content of the neuronal activity during these events is communicated to other areas such as the prefrontal cortex. A curious property of the the cortical response to hippocampal ripples is the following cortical delta wave: a short period in which the vast majority of neurons are silenced. We recently showed within this silence, some activity (~2%) remains  and that this effectively increases the signal-to-noise ratio of the cortical response, as the very little remaining activity was relevant to the hippocampal reactivation immediately preceding the memory. We believe that this process is involved in the reorganization of memory traces to integrate them in the cortical network.