Codes, operations, measurements and neural networks

Numerous neural codes and primary neural operations (logical and arithmetic al ones, mappings, transformations) were listed [e.g. Perkel, D., Bullock, T.H., 1968. Neurosci. Res. Program Bull 6, 221-348] during the past decades . None of them is ubiquitous or universal. In reality neural operations tak e place in continuous time and working with unreliable elements, but they s till can be simulated with synchronized discrete time scales and chaotic mo dels. Here, a possible neural mechanism, called 'measure like' code is intr oduced and examined. The neurons are regarded as measuring devices, dealing with 'measures', more or less in mathematical sense. The subadditivity - e minent property of measures - may be implemented with neuronal refractorine ss and such synapses operate like particle counters with dead time. This hy pothetical code is neither ubiquitous, nor universal, e.g. temporal summati on (multiplication) causes just the opposite phenomenon, the supra-additivi ty also with respect to the number of spikes (anti-measures). This is a cau se of more difficult neural implementation of OR gate, than that of the AND . Possibilities for transitional mechanisms (e.g. between traditional logic al gates, etc.) are stressed here. Parameter tuning might change either cod e or operation. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.