Memory structure created through behavioral time scale synaptic plasticity

Recent experimental studies in the awake brain have identified a new rule for synaptic plasticity that appears to be instrumental for the induction of episodic and conjunctive memories in the mammalian brain: behavioral time scale synaptic plasticity (BTSP)(Bittner et al. (2015, 2017); Grienberger and Magee (2022)). BTSP differs in essential aspects from previously studied rules for synaptic plasticity. But there is so far no theory that enables a principled understanding of the impact of BTSP on the structure of the associative memory that it induces. We extract fundamental mathematical principles from experimental data on BTSP that elucidate the capacity and associative recall capabilities of memory structures that it creates. Predictions of the resulting theory are corroborated by large-scale numerical experiments. In particular, we show that BTSP can create well-separated memory traces for a very large number of memory items, even if these are not orthogonal. Furthermore, BTSP induces the repulsion effect, a well-known fingerprint of memory organization in the human brain, that could not be explained by preceding types of synaptic plasticity. ### Competing Interest Statement The authors have declared no competing interest.