Organizing the coactivity structure of the hippocampus from robust to flexible memory.
Memories inform everyday behaviour. However, new memories are continually formed against the backdrop of our prior experiences. So, what if consecutive memories exert opposing demands on the brain? Here, we reveal how balancing the synchrony of nerve cells in the mouse hippocampus allows to effectively switch between robust and flexible memories.
New memories are integrated into prior knowledge of the world. But what if consecutive memories exert opposing demands on the host brain network? We report that acquiring a robust (food-context) memory constrains the mouse hippocampus within a population activity space of highly correlated spike trains that prevents subsequent computation of a flexible (object-location) memory. This densely correlated firing structure developed over repeated mnemonic experience, gradually coupling neurons in the superficial sublayer of the CA1 stratum pyramidale to whole-population activity. Applying hippocampal theta-driven closed-loop optogenetic suppression to mitigate this neuronal recruitment during (food-context) memory formation relaxed the topological constraint on hippocampal coactivity and restored subsequent flexible (object-location) memory. These findings uncover an organizational principle for the peer-to-peer coactivity structure of the hippocampal cell population to meet memory demands.
2019. Cell, 176(6):1393-1406.e16.
2021. Nat Neurosci, 24(3):326-330.