Data from: Progressively shifting patterns of co-modulation among premotor cortex neurons carry dynamically similar signals during action execution and observation

Many neurons in the macaque premotor cortex show firing rate modulation
whether the subject performs an action or observes another individual
performing a similar action. Although such “mirror neurons” have been
thought to have highly congruent discharge during execution and
observation, many if not most actually show non-congruent activity.
Studies of neuronal populations active during both execution and
observation have shown that the most prevalent patterns of
co-modulation—captured as neural trajectories—pass through subspaces which
are shared in part, but in part are visited exclusively during either
execution or observation. These studies focused on reaching movements for
which low-dimensional neural trajectories exhibit comparatively simple
dynamical motifs. But the neural dynamics of hand movements are more
complex. We developed a novel approach to examine prevalent patterns of
co-modulation during execution and observation of a task that involved
reaching, grasping, and manipulation. Rather than following neural
trajectories in subspaces that contain their entire time course, we
identified time series of instantaneous subspaces, calculated principal
angles among them, sampled trajectory segments at the times of selected
behavioral events, and projected those segments into the time series of
instantaneous subspaces. We found that instantaneous neural subspaces most
often remained distinct during execution versus observation. Nevertheless,
latent dynamics during execution and observation could be partially
aligned with canonical correlation, indicating some similarity of the
relationships among neural representations of different movements relative
to one another during execution and observation. We also found that during
action execution, mirror neurons showed consistent patterns of
co-modulation both within and between sessions, but other non-mirror
neurons that were modulated only during action execution and not during
observation showed considerable variability of co-modulation.