Researchers at McGill University, Canada have shown that patterns of training and learning lead to different types of memory formation.
Describing a study they conducted in the Journal of Neuroscience, they say that its significance lies in the fact that it identifies the molecular differences between spaced training (distributed over time) and massed training (at very short intervals), shedding light on brain function and guiding learning and training principles.
The researchers point out that in every organism studied, results have shown that memory formation is highly sensitive not only to the total amount of training, but also to the pattern of trials used during training.
They further state that trials distributed over time are superior at generating long-term memories than trials presented at very short intervals.
"It is a well known psychological principle that learning is better when training trials are spaced out than when given all together. However, there are very few, if any studies that identify, at the molecular level, differences between the two types of training," says Dr. Wayne Sossin, neuroscientist at The Neuro and lead investigator of the study.
"In this study, using Aplysia, a type of mollusk often used as a model of learning in which the difference between spaced and massed training has been well established, we identify an event, the activation of the enzyme called Protein kinase C Apl II (PKC Apl II), which is very different under the two training paradigms and could explain the differences in learning," Dr. Sossin adds.
The researcher says that the process of strengthening communication between nerve cells (neurons), called synaptic facilitation, represents learning and is the basis of change in learning in Aplysia.
This process is controlled by the release of a neurotransmitter called serotonin.
Four to five spaced applications of serotonin generate long-term changes in the strength of the synapse - the junction between two neurons - but in this study lead to less activation of PKC Apl II.
According to the researchers, this leads to stronger connections between neurons and increased learning and memory.
They say that if the application of serotonin is continuous, as would be the case in massed learning/training, there is much more activation of PKC Apl II.
This, they say, suggests that activation of this enzyme may block the mechanisms for generating long-term memory, while retaining mechanisms for short-term memory.
Based on their findings, the researchers came to the conclusion that the enzyme PKC Apl II is regulated differently by spaced versus massed applications of serotonin, and that the difference in activation of PKC Apl II can explain some of the distinction between spaced and massed training.