Synchrony in the Eye of the Beholder: An Analysis of the role of Neural Synchronization in Cognitive Processes

We discuss the role of synchrony of activation in higher-level cognitive processes. In particular, we analyze the question of whether synchrony of activation provides a mechanism for compositional representation in neural systems. We will argue that synchrony of activation does not provide a mechanism for compositional representation in neural systems. At face value, one can identify a level of compositional representation in the models that introduce synchrony of activation for this purpose. But behavior in these models is always produced by means conjunctive representations in the form of coincidence detectors. Therefore, models that rely on synchrony of activation lack the systematicity and productivity of true compositional systems. As a result, they cannot distinguish between type and token representations, which results in misrepresentations of spatial relations and propositions. Furthermore, higher-level cognitive processes will likely integrate information from widely distributed areas in the brain, which puts severe restrictions on the underlying neural dynamics if synchrony of activation is to play a role in these processes. We will briefly discuss these restrictions in the case of feature binding in visual cognition.