In a research that was published in the journal of Biology recently, it is reported that researchers from the University of Cambridge and the University of Plymouth have found that follow-through movements like swinging of a golf club or tennis racket, can help us to learn two different skills at once, or to learn a single skill faster. The research is significant as it can provide new insight into how tasks are learned. It could go a long way in helping people for rehabilitation, such as re-learning motor skills following a stroke.
It was found by researchers that a particular active motor memory that can be modified in the brain at any given time is influenced by both lead-in and follow-through movements. It is also seen that the skills which typically interfere can be learned at the same time given their follow-through movements are unique. It is true that in follow-through movements in sports like tennis or golf one cannot affect the movement of the ball after it has been hit. However, there are two other important purposes it serves – it helps to maximize force at the point of impact, and prevent injuries by allowing a gradual slowdown of a movement. Through this study, researchers have found a third important role for follow-through which is it allows distinct motor memories to be learned.
For example, if a new task be it serving a tennis ball or learning a passage on a musical instrument; if it is repeated enough times, a motor memory of that task develops in the brain. The brain can instruct the muscles to perform the task such that it can be performed seemingly without thinking. The issue with learning similar but distinct tasks is that there can be a certain level of interference between the two. For example, both tennis and racquetball are racket sports but the strokes for playing them are different.
To find out if we learn a separate motor memory for each task, or a single motor memory for both, the researchers carried out an experiment. They asked participants learn a ‘reaching’ task in the presence of two opposite force-fields. The participants were made to grasp the handle of a robotic interface and make a reaching movement through an opposing force-field to a central target. It was immediately followed by a second unopposed follow-through movement to one of two possible final targets. The direction of the force-field was changed, representing different tasks.
It was discovered by the researchers that the specific motor memory which stays active at any given moment is influenced by the movement that will be made in the near future. This indicates that different follow-throughs may activate distinct motor memories and hence two different skills can be learned at a time without them interfering.
Dr. David Franklin of Cambridge’s Department of Engineering, a senior author on the research remarked that since there is noise in the sensory information we receive, the planning we undertake, and the output of our motor system, every movement we make is different from the last one. Since, there is variability within our movements; there will be variability within our follow-through too.
When a person tries to re-learn skills after a stroke, he may actually exhibit a great deal of variability in his movements. Dr. Ian Howard of the University of Plymouth and the paper’s lead author opined that since now it is known that learning occurs faster when the movements are consistent; it therefore makes sense to consider methods that will reduce this variability and improve the speed of rehabilitation.