SESSION 1 PAPER CONDITIONAL PROBABILITY COMPUTING IN A NERVOUS SYSTEM

Dr. Uttley took an Honours degree in Mathematics at King's College, London where he also took a degree in Psychology and did post-graduate research in Visual Perception. At the Royal Radar establishment he designed and built analogue and digital computers. For the last five years Dr. Uttley has been working on theories of computing in the nervous system. ABSTRACT IN two previous papers it has been suggested that two particular mathematical principles may underlie the organization of nervous systems; the first is that of classification (Uttley, 1954, ref.. 13) and the second is that of. The suggestion is based on the similarity of behaviour of these formal systems and or animals. The design of classification computers is discussed in the first paper; the design of conditional probability computers Is discussed in a third paper (Uttley, 1958, ref. 15); in both papers working models are described. FUrther reference to these papers will be by date only. It is the aim of the present paper to consider whether the two principles might operate in nervous systems. Mere are four requirements for the principle of classification to operate in an area of a nervous system. Firstly, In that area, signalling must be binary; this would be the case if, for example, the impulse frequency were at either a very low rate or at a maximal rate, or if signalling were In terms of standard volleys; in general, if the fibre activity were in one of only two states. The second requirement Is that the fibres which form the input to the area be connected to neurons In as many different ways as possible; there are many areas in which this condition is met. The third requirement Is that more than one synapse of a neuron must become active for it to fire; this appears to be met. The fourth requirement is that there shall be some way of delaying signals for periods of the order of seconds. A block of isolated cortex does remain active for such periods when stimulated briefly so in this way the requirement might be met. If these conditions are all met each neuron will indicate, by firing, the occurrerze of a particular spatio-temporal pattern of activity in the input to the system.