Two behavioral paradigms for study of rapid changes in functional grouping of neurons

Recent progress in extracellular recording technology and in analytic methodology for the resulting spike trains are making practical the simultaneous registration of twenty or more neurons. This begins to make possible the direct experimental observation of functional neuronal assemblies, particularly as they dynamically change in membership or properties during a behavioral task. Behavioral paradigms appropriate for such experiments have very stringent requirements in order, with high likelihood, to produce changes in neuronal assembly structure during the time that stable recording can be maintained. We describe two motor system paradigms that seem to be appropriate, the first with crayfish claw, the second with monkey paw. The crayfish task involves a rapid learning of claw position. The monkey task involves a preset state which determines the responses to a subsequent somatosensory discrimination.