Memory formation is not an instantaneous event, but rather a dynamic process that progressively evolves across time in different brain regions. In conditioned taste aversion (CTA) learning (wherein an associative memory is formed between a palatable taste and malaise), molecular studies suggest the existence of 2 distinct memory phases in the gustatory cortex (GC): an early acquisition phase (2-3 hours following training), followed by a memory consolidation phase about 3 hours later. Recently we showed that distinct neuronal activity changes in the GC occur during these phases: the population response to the conditioned taste changes continuously, its overall magnitude only increases during the acquisition and consolidation phases, and the known quickening of the ensemble-state dynamics appears only after consolidation. These results suggest the existence of epoch-specific rules that govern neuronal network reconfiguration and taste coding changes during CTA memory acquisition and consolidation. To reveal these rules we implanted rats with Neuropixels probes in the GC and neighboring brain regions and recorded the continuous activity of hundreds of neurons simultaneously for 72 hours, before, during, and after CTA. We employed pairwise neuronal cross-correlation-based techniques to characterize the connectivity map between the recorded neurons, and single-neuron response analyses to portray the coding information of each neuron. Comparing changes in the response patterns of neurons across the learning, as well as the changes in connectivity maps highlight the rules by which memories evolve.
This research was funded by the Israel Science Foundation and the Colton Familiy foundation