Introduction to QtracW
QtracW is a flexible, stimulus response data acquisition program with averaging and threshold tracking facilities, for studies of human nerves in vivo and animal in vivo/in vitro preparations. It is best suited to situations when the excitability or response varies slowly with time, either due to changes in the stimulus parameters or to an externally initiated treatment, and the data of primary interest are the changes in selected parameters (threshold, amplitude, latency, etc.) of the response with time.
Response waveforms can also be recorded, enabling the time course of additional response parameters to be calculated after the recording is finished. QtracW comprises separate stimulation and plotting programs, QtracS and QtracP. QtracW is a multi-channel program, in which the ‘channels’ (up to 16) may be associated with different physical inputs and outputs, or with different stimulation parameters or different operations on the response waveform. Flexibility comes from the ability to associate any combination of physical or operational parameters with any channel.
The Digitimer DS5 Bipolar Constant Current Stimulator was specifically designed to work with QtracW software for human studies of nerve excitability. The major components of a human nerve excitability setup include a PC running QtracW software, a nerve stimulator (e.g. Digitimer DS5), an isolated EMG amplifier (e.g. Digitimer D440-2) and a compatible DAQ interface.
Compatible DAQ Hardware
National Instruments DAQ interfaces are recommended for use with QtracW software. Please consult the QtracW users manual for further details on specific models.
The most recent version of QtracW software can be freely downloaded from the QtracW FTP site (login details available from Digitimer upon request). After 50 days evaluation QtracW will only function through use of a USB hardware dongle/key which is provided once a licence has been purchased from Digitimer. All new licences are activated for 3 years.
All the necessary files and installation instructions are available from the QtracW FTP site.
A series of highly successful nerve excitability workshops have been held between 2009 and 2016. Further workshops may be organised in the future if there is adequate demand. Please click here for more details and contact us if you are interested in attending a workshop.
New QtracW users need to purchase a 3 year licence pack from Digitimer, with academic and clinical users receiving a 50% discount from the full price. This initial pack consists of one QtracSP dongle (stimulation and analysis/plotting) and two QtracP (analysis/plotting only) dongles. Once a user becomes a registered QtracW licencee, further dongles can be purchased individually with variable lifetimes (one to five years) and capabilities (either QtracP or QtracSP). It is also possible to extend the lifetime of a dongle by paying the appropriate licence fee. Existing QtracW users can also transfer remaining licence time from a a password on their computer to up to three USB dongles (only one QtracS) using “DongleExtend” software. Please contact Digitimer for further details.
A JoVE video article is also available which illustrates use of the DS5 and QtracW:-
We have put together an application note that illustrates the typical hardware requirements for a QtracW setup. Note that for non-human (rodent) studies, the DS5 can be replaced with our DS4 Biphasic Stimulator and the D440-2 with any non-isolated, but low noise extracellular amplifier (e.g our NeuroLog System).