PERIODIC INHIBITION OF LIVING PACEMAKER NEURONS (II): INFLUENCES OF DRIVER RATES AND TRANSIENTS AND OF NONDRIVEN POSTSYNAPTIC RATES

Abstract

This paper discusses synaptic inhibition of one pacemaker neuron by another, using data from living synapses. Spike discharges were assimilated to point processes. Inhibitory rate scale and behavior form. (i) Forms (p:q locked and others) with similar prevalent spectral components assembled monotonically with p:q. Between different lockings, intermittent, messy and other intermittent forms staggered characteristically; hoppings were interspersed. (ii) Locked, intermittent and messy forms occupied about 1/3 each of the rate scale. Individually, the 1:1, 2:1 and 1:2 locked domains were the widest, and seemed continuous; individual intermittent and messy domains were very narrow. Step-like inhibitory transients induced abrupt postsynaptic changes opposing them, which over- or under-shot and slowly returned in either orderly or complicated (chaotic?) ways to steady states. Input-output relations around inhibitory trains resembled those of first-order lead-lag systems distorted by asymmetric sensitivity to change and saturation. Postsynaptic natural discharges separated into "slow" less variable, and "fast" more variable categories with somewhat different inhibited behaviors. Formal modeling is introduced by summarizing comparable models, the data-assumption discrepancies, and reasonable conjectures as to eventual models.