MULTIPLE DEVELOPMENTAL PATHWAYS FOR MOTION PROCESSING

Purpose. Image flow across the retina can be classified into several t ypes of motion specifying information about spatial layout and self-mo vement. Adults process these types of motion via different functional pathways, This article investigates the development of these functiona l pathways. Methods. The development of sensitivity to several classes of motion is reviewed and correlated with the neural development of t he visual system, Results. Different types of motion processing develo p at different rates, The dearest example is that sensitivity to direc tion of translation shows an earlier onset and a different development al trajectory than sensitivity to shearing motion, In addition, the on set of sensitivity to translation direction and shearing motion coinci des with the development of striate laminae 5/6 and 4B, respectively. This earlier development of the deeper striate laminae is also consist ent with reports of neonatal direction discrimination in displays unde rgoing optical expansion and rotation, Conclusions, Sensitivity to at least two types of motion, translation and shearing, develop in differ ent ways and continue to be processed differently in adulthood. The di fferential development of sensitivity to these motion types coincides with the laminar development of striate cortex. It thus follows that t he nonuniform development of the motion-processing system must be reco gnized to assess infant motion sensitivity correctly.