Enhancing associative learning in rats with a computationally designed training protocol

Abstract

Associative learning requires the activation of protein kinases with distinct temporal dynamics. Learning protocols with computationally designed intertrial intervals (ITIs) that maximize the interaction between fast-activated protein kinase A (PKA) and slow-activated extracellular signal-regulated kinase (ERK) enhance nonassociative learning in Aplysia. Here, we tested whether an optimal learning protocol with irregular ITIs, predicted computationally to increase the overlap between PKA and ERK signaling in rat hippocampus, would enhance associative learning in mammals. We simulated ~1000 training protocols with irregular ITIs and identified an optimal protocol, predicted to induce stronger associative learning than standard protocols with fixed ITIs. With auditory fear conditioning, we showed that male adult rats exposed to the optimal conditioning protocol exhibited stronger fear memory retrieval and impaired fear memory extinction, compared to rats that received either massed or spaced conditioning protocols with fixed ITIs. With fear extinction, we likewise observed that fear conditioned rats exposed to the optimal extinction protocol showed improved extinction of contextual fear memory, compared to rats that received standard extinction protocols. Together, these findings demonstrate the capacity of a behavioral intervention driven by a computational model of memory-related signaling pathways to enhance associative learning in mammals and may provide greater insight into strategies to improve cognition in humans.