New Motor Memories May be Fleeting

The performance of many motor skills have been ingrained into our memory so that the action can be seamlessly recalled even after decades of non-use. Examples include riding a bike or catching a ball — things we can do without thinking of the particular components of the action.

A new study shows, however, that learning to perform a skill takes more than just one session of training. As published in PLOS Computational Biology, researchers discovered changes to motor skill memories occurring over the course of a single practice session are not immediately stable.

The example of never forgetting how to ride a bike highlights the incredible stability possible for motor skill memories, especially those for well-practiced skills. However, the new study questions if motor memories can be remembered over time after a single session.

For the investigation, researchers addressed two theories of motor memory. One theory maintains there is a bank of intrinsically stable memories that can be laid down in just a few minutes of practice and that are highly specific to the context surrounding the training.

An alternative theory maintains that new motor memories are intrinsically somewhat unstable and tend to be applied over a range of different contexts. Such instability could be beneficial in changing environments, such as maintaining one’s running stride while muscles fatigue or donning eyeglasses that will soon be removed, especially if the persistence of the memory tends to match the persistence of environmental changes.

From the research, investigators found strong evidence that recent changes to motor memories are in fact intrinsically unstable and not strongly context dependent. This suggests each memory is applied in a range of contexts and the motor system would thus require fewer distinct memories.

The instability observed in new motor memories stands in stark contrast to the long-term stability of well-practiced skills like riding a bike.

Researchers say this contrast raises the critical question: how can new motor memories eventually become so stable? Additional research is needed to answer this question although practicing an activity is unquestionably necessary to develop long-term motor memory.

Source: PLOS Computational Biology