Information on the modalities of transmitter release at the cyto-neural junction was derived from the analysis of the EPSP discharge, intra-axonaily recorded from the posterior nerve either at rest or during sinusoidal canal rotation. The high EPSP emission rate (often >100 s-1 ) results in temporal summation and overlapping of the individual events. A noise analysis procedure, using higher moments of fluctuations in membrane potential, was developed to evaluate EPSP amplitude and frequency. EPSP response was quantified in terms of maximum and minimum peak rates as well as of total numbers of EPSPs normalized to the spontaneous activity. With respect to the resting level, the increase in EPSP rate produced by the excitatory phase of stimulation was more conspicuous than the decrease in EPSP frequency observed during the corresponding inhibitory phase of rotation. Both maximum and minimum EPSP rates were linearly related either with peak acceleration or with its logarithm. A consistent adaptation characterizes excitation. The results suggest that response asymmetry, adaptation and intensity function are intrinsic features of the synaptic transmission mechanism being then mirrored in the spike discharge pattern.
FUNCTIONAL PROPERTIES OF THE POSTERIOR CANAL AFFERENT SYNAPSE IN THE ISOLATED FROG LABYRINTH
ROSSI, Marialisa;MARTINI, Marta;BONIFAZZI, Claudio;
1989
Abstract
Information on the modalities of transmitter release at the cyto-neural junction was derived from the analysis of the EPSP discharge, intra-axonaily recorded from the posterior nerve either at rest or during sinusoidal canal rotation. The high EPSP emission rate (often >100 s-1 ) results in temporal summation and overlapping of the individual events. A noise analysis procedure, using higher moments of fluctuations in membrane potential, was developed to evaluate EPSP amplitude and frequency. EPSP response was quantified in terms of maximum and minimum peak rates as well as of total numbers of EPSPs normalized to the spontaneous activity. With respect to the resting level, the increase in EPSP rate produced by the excitatory phase of stimulation was more conspicuous than the decrease in EPSP frequency observed during the corresponding inhibitory phase of rotation. Both maximum and minimum EPSP rates were linearly related either with peak acceleration or with its logarithm. A consistent adaptation characterizes excitation. The results suggest that response asymmetry, adaptation and intensity function are intrinsic features of the synaptic transmission mechanism being then mirrored in the spike discharge pattern.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
