TIMING OF NEURAL COMMANDS - A MODEL STUDY WITH NEURONAL NETWORKS

Networks constructed of biologically realistic model neurons (neuroids ) were used to study how in a neural assembly using pulse (interval)-c oded information slow rhythmical oscillations with possible mode trans itions might occur and how the efferent commands might be structured a nd their phase-shifts created. The simulations show that slow oscillat ions (in the hertz range) can be derived from reverberatory spiking in relatively short closed loops (fewer than ten neuroids) with the inpu ts protected against disturbing afferent signals and the outputs coupl ed by convergence on a common neuroid. Slow oscillations can be modifi ed by a tonic activity entering the network; this activity changes the transmission time in the coupled loops involved. The structuring of t he regulatory commands (in the millisecond range) was achieved by simu lation of sequential activity propagation in a non-ring neuronal assem bly supervised by a tonic activity in a set of inputs. The tonic activ ity acted as an instructive signal influencing the pattern of the func tional connectivity in such a way that a particular efferent command w as generated by the instructed network.