Method of evaluating the synaptic influx to the single neurone of the mid-brain

The mathematical model of the generation of impulses by a neurone receiving synaptic influx from a multiplicity of other neurones [1] satisfactorily describes the impulse activity of five of the seven extracellularly investigated neurones in the tegment of the mid-brain of the mesencephalic cat and its changes due to the electrophoretic micro-application of glutamate. For the neurones satisfying the model, evaluations are obtained of the mean frequency of the total synaptic influx, the threshold depolarization and the time constant of the drop in the e.p.s.p. For the different neurones the values of these parameters were 4-100 kc/s, 100-800 mean unit e.p.s.p. and 4-30 msec respectively. The steady value of the mean ongoing potential of all five neurones was heavily shifted from the resting potential to the threshold of generation of an impulse. By applying glutamate it was possible in all these neurones to shift the steady value of the mean ongoing potential so much that it exceeded the threshold of the generation of an impulse.