Synchrony Unbound A Critical Evaluation of the Temporal Binding Hypothesis

Singer, 1994). The basis for this argument is that it is necessary to " tag " each visual neuron to signify the object to which its activity relates. Each neuron therefore has to carry two distinct signals, one that indicates how effective a stimulus is falling on its receptive field, and a second that tags it as a member of a particular cell assembly. To make these signals distinct, von der Mals-Center for Neural Science New York University burg (1981) proposed that the " effectiveness " signal would be carried by a conventional rate code, while the New York, New York 10003 " tag " signal would be created by synchronizing the spike activity of the neuron with spikes from other neurons in Introduction the same assembly. This novel idea has led to a great deal of experimental work and to several further elabora-In the early stages of visual processing, objects and scenes are represented by neurons with small visual tions of the original theory. In this paper, we will articulate our doubts and con-receptive fields. Each neuron provides information about local features of a scene, but to describe a scene in cerns about this theory and its experimental support. We consider first whether the theory is an a priori reasonable terms of objects requires that these features be combined. Objects can cover wide areas of visual space and approach to solving the binding problem, and conclude that it is at best incomplete. We then ask whether spike be partially occluded by other objects, so the problem of binding the separate representations of parts into synchrony can plausibly be used as an informational code, and conclude that there are significant practical coherent wholes is not a simple one. This " binding problem " has received considerable attention. Gestalt and theoretical obstacles both to encoding and to decoding information in this way. We then examine the psychologists articulated a number of principles for grouping and organizing scene elements (Kö hler, 1930; experimental evidence usually adduced to support the synchrony hypothesis, and conclude that the evidence Koffka, 1935; Kanisza, 1979), and more recently the related problem of image segmentation has received a is largely indirect and has no proven relevance to the issue of binding per se. We will finish by asking whether good deal of attention in computer vision (see, for example , Pal and Pal, 1993, for a review). The …