Instruction manual

6 Input and Output 93
Rise time: The time taken to go from the Start Amplitude to the Stop Amplitude
# Triangles: Number of Triangles
IR: Time between Triangles
HP: Holding potential
Apply: Applies any changes to the stimulus protocol made through the Stimulator Toolbar.
Clicking Apply while recording will send a stimulus pulse from the output
Note: The Stimulator preferences dialog will draw whatever protocol you specify. Be sure to examine the
output representation carefully before closing the dialog to confirm that this is in fact the output that you
want.
Stimulator
Display
On WPI 214/118/3xx, the stimulator output can be displayed as a channel in the Main window.
Stimulus
Protocols
Built with the
Sequence
Builder
Experiments are often designed to record the response of a cell (or a tissue) to progressively
larger or more frequent stimuli. In these cases, parameters of the stimulus are changed before
each recording of the cell’s response to the next stimulus. The Sequence Builder, a page in the
Preferences dialog window, can be used to automatically change parameters of the stimuli
released from the DAC.
For example, excitable tissues like nerves and muscles are composed of multiple fibers, each
with a different diameter, conduction velocity and threshold. Fibers with higher thresholds
require a larger stimuli to evoke their action potentials. Increasing the amplitude of the stimulus
sent to the excitable tissue will cause more fibers in the tissue to fire. This is known as
recruitment and is measured as an increase in the amplitude of the tissue’s compound action
potential.
In Scope mode, the Sequence Builder and other pages (Channels, Stimulator) in the
Preferences dialog window can be used to record each response of the excitable tissue to a
stimulus and automatically increase the amplitude of the stimulus between each trial.
Channels Page To construct an example of an Sequence designed to control the DAC and to record in Scope
mode, select Preferences from the Edit menu. On the Channel page of the Preferences dialog
window set:
Acquisition Mode Scope: Multiple
Number of Sweeps 10
Delay Between Sweeps 2
Start User
Stop Timed: 0.03 sec
Sampling Speed 20000
Display Time 0.030 sec
Select A1 Raw Channel 1: set Mode to BNC
Deselect A2-A4 i.e. raw channels 2, 3 and 4
Select S1 stim 1: Set Mode to Record.