Association Between Fast and Slow Learning and Molecular Processes in Repetitive Practice: A Post Hoc Analysis

Abstract

The explanations for the positive effects of less repetitive practice in learning, compared to more repetitive practice, converge towards an idea of a greater memory strengthening in less repetitive practice. These benefits are associated with the AMPA glutamate receptor. However, there are no studies in the literature that explain, in molecular terms, how memory processes during practice (or acquisition) are associated with these benefits. Overall, the process of memory strengthening in the acquisition of a motor skill has two distinct stages: a fast initial performance improvement followed by a gradual change associated with the memory state termed slow learning. Computational models, like the multi-rate learning model, help to identify these two distinct stages (fast and slow learning). This study aimed to investigate if the AMPA receptors are associated with the memory’s fast state (fast learning) and slow state (slow learning). Mice (n = 30) practiced the rotarod in two days of constant (one rotation frequency) or varied (three different rotation frequencies) practice. Animals were tested both 24 h and 10 days after acquisition. Two analyses were conducted, stepwise discriminant analysis and analysis of the difference between the predicted and observed values. Varied practice was more associated with the slow state. The findings of the present study advance in the explanations of the molecular mechanisms underpinning the greater memory strengthening proposed by behavioral hypotheses. Furthermore, we propose an alternative explanation for the explanations formulated at behavioral level, highlighting the role of the reference of the error that is produced trial-to-trial.