Stimulus Protocols > Voltage Stimulus Stimulus Waveforms
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Rectangular voltage pulse of fixed size This is a simple pulse, which does not vary in amplitude and duration between records. It has 3 parameters. Initial Delay: the delay period before the pulse begins. Amplitude: the pulse amplitude (mV). Duration: the duration of the pulse. This element can be used to provide series of stimuli of fixed size or, in combination with other elements, to provide fixed pre-conditioning pulses. |
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Family of rectangular pulses varying in amplitude This is a rectangular voltage pulse whose amplitude is automatically incremented between recording sweeps. It has 5 parameters. Initial delay: the delay period before the pulse begins. Start at Amplitude: the amplitude of the first pulse in the protocol sequence. Increment by: the increment to be added to the pulse amplitude between records. Number of increments: the number of steps in the sequence. Pulse duration: the duration of the pulse. This element is typically used to explore the voltage-sensitivity of ionic conductances, by generating records containing the whole-cell membrane currents evoked in response to a series of voltage steps to different membrane potentials. |
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Family of rectangular voltage pulses varying in duration This is a rectangular voltage pulse whose duration can be automatically incremented between recording sweeps. It has 5 parameters. Initial delay: the delay period before the pulse begins. Amplitude: the amplitude of the pulse. Pulse duration: the duration of the pulse. Increment by: the increment to be added to the pulse duration between records. Number of increments: the number of steps in the sequence. This element is most commonly used as a variable duration preconditioning pulse in 2 or 3 step protocols for investigating inactivation kinetics of Hodgkin-Huxley type conductances. |
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Train of rectangular voltage pulses This is a train of rectangular voltage pulses of fixed size. It is defined by 5 parameters: Initial delay: the delay period before the series of pulses begin. Amplitude: the amplitude of each pulse in the series. Duration: the duration of each pulse. Pulse interval: (within train) determines the time interval between pulses. Number of pulses: defines the number of pulses in the train. This element can be used to produce a series of stimuli to observe the effect of repeated application of a stimulus at a high rate. It can also be used to produce a train of pre-conditioning stimuli for a subsequent test waveform. |
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Voltage ramp This element produces a linear voltage ramp between two voltage levels. It is defined by 4 parameters Initial delay: the delay period before the series of pulses begin. Start at amplitude: the voltage level at the start of the ramp. End at amplitude: the voltage level at the end of the ramp. Ramp duration: the time taken for the voltage to slew between the start and end amplitudes. Voltage ramps provide a means of rapidly generating the steady state current-voltage relationship for an ionic conductance. (Note that, the ramp generated by the computer is not truly linear, but consists of a staircase of fine steps. These steps can be smoothed out, by low-pass filtering the voltage stimulus signal before it is fed into the patch clamp.) |
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Digitised analogue waveform Digitised analogue waveforms which have been previously acquired by WinFluor (or synthesised by another program) can be used as a waveform element. To insert a digitised waveform into the protocol: Select the source of the waveform and copy it to the Windows clipboard. Waveforms may be copied from a WinWCP signal record (using the Edit/Copy Data menu option) or from a spreadsheet or similar program. Drag a digitised analogue waveform icon from the toolbox and drop it into the protocol list. Insert the waveform into the protocol by clicking the The parameters table consists of: Initial delay defines the delay period before the series of pulses begin. A list of data points for the analogue waveform. The waveform can be altered by modifying this list. There are a number of limitations when using the digitised waveform element. Only one digitised waveform element is permitted per protocol. Digitised waveforms must consist of less than 1000 data points. The sampling interval of the digitised waveform must be greater than 0.1 msec. If digitised waveforms are created with a spreadsheet, the data points must be formatted as a pair of columns containing time (msecs) in the first and amplitude (mV) in the second. E.g.
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