A neuronal mechanism for the processing of random-dot motion in areas 17 and 18.

<p>(A) The illustration of how single-neuron behavior accounts for differential population responses. Diagrams of the stimuli (0°–180°) used for generating differential direction responses are shown at the top. The patterns of the differential response images are similar across different speeds, but not the differential response strengths. The solid circles indicate regions that prefer rightward motion (0°), while areas in dotted circles prefer leftward motion (180°). The length of the arrows in the solid/dotted circles represents the response strength of the underlying direction-selective neurons to different directions. The corresponding direction tuning curves under different speeds for neurons preferring a 0° direction are shown as an example at the bottom. (B) Summary of the behavior of orientation- and direction-selective neurons with orthogonal preferences in the processing of the rightward motion at different speeds. The colored circles represent for orientation- and direction-selective neurons with vigorous responses, while those gray circles indicate less active or silent neurons in the processing of the rightward motion below and above the transition speeds. Markers inside these circles indicate stimulus features encoded by the neurons: bar for orientation, dotted line for motion axis, and arrow for direction. Note that direction-selective neurons in area 18 maintain some responses to rightward direction at high speed.