THE IMPLICATIONS OF BINDING FOR MODELS OF COGNITIVE BRAIN FUNCTION

摘要

In the brain, knowledge must be represented in separate maps, such as location, identity, rank order, and procedures. Solutions to the binding problem based on 'conjunctive nodes' and specific temporal codes are reviewed in the light of mechanisms of self-organization. A conceptual network will be discussed in which memory traces are carried by cell-assemblies with a critical threshold: when sufficient neurons are externally activated the overall activation level in the cell-assembly rises to its maximum by itself. Propagation of oscillatory excitation loops can take place above the critical threshold - the corresponding memory traces are then said to be in short-term memory - or below the critical threshold - the involved memory traces are then in a state of priming. The bindings between the various maps at the neural level are assumed to exist in the form of temporary resonances between excitation patterns in cell-assemblies or in a spatial map. Two patterns are bound because they are active simultaneously and because they are activated from a common subnetwork that represents the momentary context in which the network is functioning. Different forms of binding are discussed, illustrating the binding of location and identity and that of rank order and identity. A computer simulation and an experiment in relation with the former is described.