Analysing Single-channel Currents > Detecting Channel Transitions > Transition Detection
While analysis of current amplitude provides information concerning the number and size of channel conductance states it provides no information about channel kinetics. In order to do this it necessary to measure the time the channel spends in each state. Since ion channels fluctuate randomly between open and closed states the duration of a single opening or closure provides little information. It is necessary to measure the durations of hundreds or thousands of openings and closures and to analyse the distribution of dwell times spent in each state.
The Detect Transitions page provides tools for the detection of channel open/close transitions and the determination of the sequence of channel dwell times spent in each state.
The simplest approach to the classification of the single channel current signal into open and closed states is to place a transition threshold at the mid-point between the zero and single-channel current levels. If the signal lies above the threshold the channel is deemed to be open, if it lies below the channel is deemed to be closed. An 'idealised' sequence of channel open and closed periods is thus obtained by scanning through the digitised recording point by point, counting the time between threshold crossings.