  Previous work in the area of gesture production, has made the assumption that
machines can replicate "human-like" gestures by connecting a bounded set of
salient points in the motion trajectory. Those inflection points were
hypothesized to also display cognitive saliency. The purpose of this paper is
to validate that claim using electroencephalography (EEG). That is, this paper
attempts to find neural signatures of gestures (also referred as placeholders)
in human cognition, which facilitate the understanding, learning and repetition
of gestures. Further, it is discussed whether there is a direct mapping between
the placeholders and kinematic salient points in the gesture trajectories.
These are expressed as relationships between inflection points in the gestures'
trajectories with oscillatory mu rhythms (8-12 Hz) in the EEG. This is achieved
by correlating fluctuations in mu power during gesture observation with salient
motion points found for each gesture. Peaks in the EEG signal at central
electrodes (motor cortex) and occipital electrodes (visual cortex) were used to
isolate the salient events within each gesture. We found that a linear model
predicting mu peaks from motion inflections fits the data well. Increases in
EEG power were detected 380 and 500ms after inflection points at occipital and
central electrodes, respectively. These results suggest that coordinated
activity in visual and motor cortices is sensitive to motion trajectories
during gesture observation, and it is consistent with the proposal that
inflection points operate as placeholders in gesture recognition.
