Using Stimuli

The Stimuli window comprises up to four vertically stacked sections, each used to configure pulses and pulse trains to be sent to one analog or digital output. When you click “Run”, all the configured pulse trains are sent to their respective outputs, with synchronization between channels. At the end of the longest train, the run automatically ends, unless you have checked “Repeat”, in which case output continues indefinitely.

Hardware

Use the “Hardware” button to choose which DAQ board will be used and the sample rate of the generated signals.

Channels

Use the “Channels” button to configure which outputs are used. If your output is connected to a device like an AxoClamp, you may like to set scale factors here. That way, the graphs and configuration buttons on the main screen will display physical units.

Configuring pulses

Four pulse types are currently supported: “Monophasic”, “Biphasic”, “Ramp”, and “Sine”.

A “Monophasic” pulse is defined simply by its amplitude and duration.

A “Biphasic” pulse is defined by the amplitudes and durations of its first and second phase, which may be different.

For a “Ramp” pulse, the “Amplitude” defines the starting voltage of the ramp (which may usefully be set to zero), whereas the “2nd amp.” defines the final voltage.

For a “Sine” pulse, the “Amplitude” is measured center-to-peak, the “Duration” is the full period of the wave. The “2nd amp.” is used as an offset (which may usefully be set to zero), whereas the “2nd. dur.” is used as a phase shift.

In all cases, the graph above the settings automatically updates to reflect a preview of the pulse you are about to send out.

Configuring trains

The right half of the configuration panel is used to define pulse trains. A full stimulus may comprise any number of trains, each consisting of any number of pulses. The “Pulse period” and “Train period” are always measured start-to-start. The “Delay” is mainly useful when multiple channels are in use. Unless your stimulus comprises only a single pulse in a single train, the graph above the train settings reflects the full stimulus.

If there are are multiple pulses in your train(s), the main pulse parameters define the first pulse within each train, and the “Chg./pulse” column may be used to modify the subsequent pulses. For instance, you could create a train in which each subsequent pulse is a little stronger than the previous by setting the “Chg./pulse” for “Amplitude” to a positive number. The waveform display is updated to show all of the pulses, using a lighter shade of blue for all but the first.

Likewise, if there are multiple trains, the “Chg./train” column may be used to modify the second and later trains. You can even change the number of pulses between trains. The waveform display is updated to show all of the pulses, with pulses from all but the first train plotted in gray.

Loading and saving configurations

The “Load” and “Save” buttons may be used to save configured pulses for later use.