QTMS screenshot

QTMS Extension to QtracW Software

Automated Control of TMS Stimulators for Solo Operators

QTMS LogoQtracW is a flexible, stimulus-response data acquisition program with averaging, threshold-tracking and latency-tracking facilities, originally written for studies of human nerves in vivo.  For those unfamiliar with the application of QtracW software in studies of nerve excitability, we recommend the recent article by Prof. Matthew Kiernan and colleagues (Kiernan et al. 2020), which provides guidelines for the measurement of axonal excitability and provides a state of the art review of axonal excitability research. Here we introduce an extension for QtracW which facilitates solo measurements of cortical excitability using TMS.

New Applications for Threshold Tracking

QtracW is increasingly being used for microneurography, muscle excitability testing and cortical excitability testing with transcranial magnetic stimulation.  Although control of magnetic stimulators has been possible for several years under standard QtracS protocols, Prof. Hugh Bostock and his colleagues at QTMS Science Ltd. have recently launched a new QTMSG recording suite specifically aimed at TMS users, allowing a solo operator to run QtracW TMS protocols and obtain standardized recordings automatically.

In addition to resting motor threshold (RMT), stimulus response function (SRF) and cortical silent period (CSP), this QTMSG suite comprises short interval intracortical inhibition and facilitation (SICI, SICF), long interval cortical inhibition (LICI), and short latency afferent inhibition (SAI).  In each case, conventional tests can be compared directly with two corresponding threshold-tracking versions, serial and parallel.  In the serial tracking versions, as in the TRONDNF nerve excitability protocols, test-alone stimuli on one channel are compared with conditioning+test stimuli on another, and the interstimulus interval (ISI)changed in steps.

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Responses are typically displayed as a combination of raw data and plots, illustrating changes in parameters of interest.


Enhanced QTMS Functions

Although serial tracking has been kept on from earlier versions of QTMS.QRP, and a serial SICI protocol has been proposed as a diagnostic tool for ALS, it is no longer recommended, as it has been found that rather different SICI results are obtained if the ISIs are changed in reverse order. Instead the developers recommend conventional amplitude measurements or the parallel tracking versions, in which conditioning+test stimuli at each ISI are tracked in parallel on separate channels1.  An optional gating facility is incorporated, so that spontaneous activity or temporary failure to relax causes responses to be ignored.  Moreover, monophasic paired TMS pulses can now be delivered with DuoMag (DuoMag MP Dual), and NeuroSoft (Neuro-MS Paired Monophasic stimulator) as well as MagStim (BiStim2) hardware, with stimulation rates up to once every 1.5 seconds (DuoMag).

QtracW may be configured to communicate and control devices including the Digitimer DS5 stimulator, D440 amplfier and a range of magnetic stimulators.


Each Magnetic Stimulator has Different Hardware Connection Requirements

These TMS devices are all designed to deliver paired monophasic magnetic stimuli through a single coil, although they all achieve this result in slightly different ways. Thus the BiStim requires one serial connection and two TTL trigger inputs, the DuoMag requires two USB connections and two trigger inputs, while the NeuroSoft requires just one USB connection and one trigger input.  It is recommended that QtracW is used in conjunction with a compatible National Instruments data acquisition interface which is used to trigger the TMS device(s) and to collect the EMG responses.  Full details of the new recording software, and also the new analysis and plotting facilities in QtracP.EXE, will be found in the new QtracW & TMS manual and the use of this software to compare 3 methods of SICI recording is described by Tankisi et al. (2021).

QTMS researchers equipment and screenshot
Dr Liane Phung (University of Toronto) and Dr Kelvin Jones (University of Alberta) conducting cortical excitability testing with the Magstim Bistim and QTMS protocols.

The QTMSG series of TMS software protocols can be used only with the QtracS.EXE program.  The intellectual property rights of this software, which belong to QTMS Science Ltd., are protected by encryption as a QRPZ (encrypted QRP) file, for use only in conjunction with a particular QtracSP dongle.

Three types of QTMSG QRPZ file can be issued on request:

  1. A free trial version, for use only during a QtracW 50-day free trial period.
  2. A 50-day free trial version, for use with a specific QtracSP dongle.
  3. A regular version, for use with a specific QtracSP dongle, and available for a whole number of months, between 12 and the last month of validity of the dongle.

Requests for quotations should be directed to Digitimer, as we are acting as agents for QTMS Science Ltd.  All QTMSG licence or free trial requests must be accompanied by the code of the relevant QtracSP dongle (which can be obtained from the dongle by running the Qtrac utility DongleRead.EXE or DongleCheck.EXE).  Free trial versions may only be obtained from Professor Hugh Bostock (H.Bostock@ucl.ac.uk).



Kiernan, M. C., Bostock, H., Park, S. B., Kaji, R., Krarup, C., Krishnan, A. V., … Burke, D. (2020). Measurement of axonal excitability: Consensus guidelines. Clinical Neurophysiology, 131(1), 308–323.

Tankisi, H., Cengiz, B., Howells, J., Samusyte, G., Koltzenburg, M., & Bostock, H. (2021). Brain Stimulation Short-interval intracortical inhibition as a function of inter-stimulus interval : Three methods compared. Brain Stimulation, 14(1), 22–32. https://doi.org/10.1016/j.brs.2020.11.002