Synaptic evidence for the efficacy of spaced learning

• DOI: 10.1073/pnas.1120700109
• Publication Date: 2012-03-13T05:00:12Z
• Authors: Enikö A. Kramár; Alex H. Babayan; Cristin F. Gavin; Conor D. Cox; Matiar Jafari; Christine M. Gall; Gavin Rumbaugh; Gary Lynch
• Keywords: Male; Time Factors; Dendritic Spines; Long-Term Potentiation; In Vitro Techniques; Synaptic Transmission; Actins; Polymerization; Rats; Mice, Inbred C57BL; Rats, Sprague-Dawley; Mice; 03 medical and health sciences; 0302 clinical medicine; Synapses; Animals; Learning; Theta Rhythm

The superiority of spaced vs. massed training is a fundamental feature learning. Here, we describe unanticipated timing rules for the production long-term potentiation (LTP) in adult rat hippocampal slices that can account one temporal segment trials phenomenon. Successive bouts naturalistic theta burst stimulation field CA1 afferents markedly enhanced previously saturated LTP if apart by 1 h or longer, but were without effect when shorter intervals used. Analyses F-actin-enriched spines to identify potentiated synapses indicated added obtained with delayed trains involved recruitment "missed" first bout. Single spine glutamate-uncaging experiments confirmed less than half hippocampus are primed undergo plasticity under baseline conditions, suggesting intrinsic variability among individual imposes repetitive presentation requirement maximizing percentage connections. We propose combination local diffusion from initially modified coupled much later membrane insertion events dictate repetitions be widely spaced. Thus, synaptic mechanisms described here provide neurobiological explanation component poorly understood, ubiquitous aspect