Post by Deborah Joye
What's the science?
An important foundation of acquiring new skills is the ability to learn by watching others. But how does the brain connect what we see to our own motor movements? When we learn a new skill through physical practice, activity patterns in our frontoparietal brain regions become more precise and coordinated – encoding a specific representation of the activity we are learning. These brain regions include the pre-motor and sensorimotor cortices, which are responsible for planning and executing movements. Can these changes in brain activity occur when learning something just by watching someone else move? This week in Journal of Neuroscience, Apšvalka and colleagues use functional imaging to demonstrate that observational training results in brain activity changes similar to those caused by physical practice.
How did they do it?
Sixteen right-handed male and female participants (ages 20-40) were asked to learn a key-press task by watching videos of the task being performed by someone else. Participants completed a pre- and post-training functional magnetic resonance imaging (fMRI) session to visualize their brain activity while they watched the videos, as well as pre- and post-training sessions in which they performed the task themselves. For 4 days between these two fMRI sessions, participants completed the observational training where they learned key-press sequences by watching videos and reporting any errors made. The authors analyzed fMRI data (using conventional univariate fMRI analyses) before versus after training to determine whether observed key-press sequences were represented by patterns of activity in the frontoparietal cortex. During fMRI and testing sessions pre- and post-training, participants were shown sequences they also saw during observational training, as well as sequences they did not see. The authors could, therefore, analyse whether sequence-specific brain activation was stronger for sequences that participants had been trained on (versus those they had not). They then analyzed frontoparietal cortex activity, using multi-voxel pattern analysis (MVPA) which evaluates how activity patterns across a population of voxels (like 3D pixels in a brain image) change over time. This analysis provides a more nuanced investigation of activity changes in a particular brain region because it considers patterns of activation at each voxel, rather than for a region as a whole, capturing information that could be lost with conventional fMRI analysis.
What did they find?
The authors found that participants were able to accurately learn and perform sequence patterns and could consistently report errors during observational training, suggesting that they paid close attention to the instruction videos. Brain areas activated by observational training closely resembled those activated by physical practice, including the premotor cortex which is responsible for planning motor movements. As expected due to the observational nature of the training, the primary motor cortex – responsible for executing motor movements – was not specifically activated. The authors observed activation of frontoparietal networks in the brain that have also been found previously to activate during observed practice studies. Some regions of the frontoparietal cortex showed decreased activity after training, suggesting an increase in neural efficiency. Using multi-voxel pattern analysis, the authors found that frontoparietal regions exhibited less overall activity after training and showed unique activity patterns for different key-press sequences. These activity patterns generalized to similar key-press sequences regardless of whether or not the participant had been trained on those sequences.
What's the impact?
These findings suggest that observed actions are encoded in the brain by distinct patterns of activity in the frontoparietal cortex. This study is the first to demonstrate on the neural level that observing an action or physically practicing it produce similar changes in brain activity patterns. Specifically, planning and association areas of the brain such as the premotor and parietal cortices encode distinct representations of actions learned by observation. These findings help us understand how the brain stores observed actions and connects them with our own motor movements when we are learning something new.
Apšvalka et al. Observing action sequences elicits sequence-specific neural representations in frontoparietal brain regions. The Journal of Neuroscience (2018). Access the original scientific publication here.