Regulation of division of labour between cognitive systems controlling action

The brain has evolved a division of labour amongst component systems which link different sorts of processing with precise actions. Debate is over centralized versus decentralized control at different processing levels, from cognitive systems to motor-control systems. With simultaneous activation of alternative expert systems which link (a) picture-processing with drawing and (b) reading with writing, decentralized modelling predicted both the averaging of action-production times and additive effects of neural noise. Such modelling has the advantage of being able to measure the cost of regulation both within and between systems, in a common metric of performance variability. That commonality strengthens the trend to regard the brain as a distributed super-system with a great deal of regulation done towards the output end. (C) 2000 Elsevier Science B.V. All rights reserved.