Fig. 3

Examples of directional tuning in intra-cortical signals. Diagrams showing the directional tuning properties of the neurons in non-human primate M1 from the data in [215, 216]. a Spike raster plots from one of the neurons (Neuron 31). Each plot shows the spike timing of the neuron aligned to the time point (t=0) at which the movement speed of the hand exceeds a pre-defined threshold. Each dot in the plot represents an action potential. Different plots indicates the neuronal activity when the hand is moving in different directions. b The von Mises tuning curve of some of the representative neurons. c The preferred direction of all the neurons. The length of the vector represents the modulation depth of the neuron, here defined as the magnitude of the tuning curve divided by the angle between the maximum and minimum point on the curve