Publication Summary and Abstract
Redgrave, P., Prescott, T.J., & Gurney, K. (1997), The basal ganglia: a neural architecture for conflict resolution, Soc Neurosci Abstr, 23:192.
The problem of conflict resolution arises whenever multiple command systems are in competition for a limited set of effectors. At any time only one directing system can be allowed control of a given set of motor outputs. A model is presented in which selection processes in the BG (basal ganglia) (described by Mink, 1996) are seen as the vertebrate solution to the conflict problem. Connectivity in the model is inspired by relevant neuroanatomical electrophysiological data. Multiple, independent cortical and subcortical systems which can direct movement (action generators) have colateralised excitatory connections with cortical/brainstem movement generators and the striatum. The movement generators are restrained by tonic inhibitory input from the BG. Dynamic 'winner-take-all' computations (Wickens 199?) in the BG withdraw inhibition from movement effectors accessed by 'winning' action generators and increase it on effectors contacted by 'losers'. The Heavy collateralisation of BG output-one branch completes the cortico-BG-thalamocortical loop while others contact one or more movement generators-suggests that selection in the BG may be at the level of 'actions' (e.g. feeding) rather than 'action components' (e.g. sequential hand, head and mouth movements). Positive feedback provided by the return thalamocortical loop can sustain activity in the selected action generator relative to non-selected channels. Within this system the short latency dopamine response (Shultz 199?) can be viewed as a 'global interrupt' which briefly suppresses activity in selected channels thereby initiating re-prioritisation. Other signals related to positive and negative outcome adjust the probabilities of context-specific selections between competing channels. This model is under active investigation using computer simulation, and ensures the effective resolution of conflict between multiple systems competing for access to the final common motor path.