A long closed state of the synaptosomal bursting potassium channel confers a statistical memory

The statistical properties of the bursting potassium channel from fused Torpedo synaptosomes were studied by using patch-clamp recording and time series analysis. Voltage steps produce channel openings; the number of channels opening fluctuates from trial to trial. The maximal current observed in each trial is strongly dependent on the previous history of the membrane patch. Trials with no activity are frequently clumped together and so are trials with intense activity. Autocorrelation analysis reveals a strong interdependence of successive responses, which is voltage dependent. We propose that the strong statistical interdependence of responses to successive depolarizing pulses (the statistical 'memory') is a manifestation of a long lived closed state. We speculate that this statistical memory may be of significance in frequency modulation of transmitter release.