Quantization of motor activity into primitives and time-frequency atoms using independent component analysis and matching pursuit algorithms

It has been proposed that the segmental spinal nervous system may organize movement using a collection of force-field primitives. The temporal organization of primitives has not been examined in detail. Recent data examining muscle activity underlying corrections of motor patterns suggested that primitives might be recruited into motor programs as waveforms with a constant duration. Here we test the idea that each primitive or premotor drive comprising part of the motor patterns might be expressed as the combination of a small number of time-frequency atoms from some orthonormal basis. We analyze the temporal organization of pre-motor drives extracted from the motor pattern by the Bell-Sejnowski algorithm for independent component analysis. We then use matching pursuit cosine packet analysis to examine the time series of the activation waveforms of each of the independent components. The analysis confirms that the motor pattern can be described as a combination of a small number of time-frequency atoms. These atoms combine to generate the temporal structure and activation of the individual components or premotor drives that generate individual muscle activity.