The study results in the field of non-invasive brain stimulation are very heterogeneous and the replication crisis has hit the field (quite/very/unsurprisingly) hard. Over the next few posts, I will elaborate on some of the contributing factors and will provide some insights into the steps we have taken / are taking at Pulvinar to help researchers increase the quality of their work and thereby lift up the field. Today, I am writing about quality control and traceability. Quality control is a basic principle were actions are not only planned and performed but also their outcomes assessed to improve the underlying processes. Simple? Yes! Important? Yes! Does your tDCS/tACS device help with this? You tell me and I will tell you about XCSITE 100 ;-)
Typically, stimulation is performed by pressing some buttons on a device (or in a program). Once the stimulation is over, there is no way to verify if the person has received the correct stimulation (waveform). User mistakes can and will happen, especially in the high-stress environment of stimulation patients in clinical trials and if the personnel administering stimulation are not engineers, who are usually more comfortable with operating sophisticated devices. The lack of accountability and the lack of evidence for correct stimulation is fully and simply inconsistent with any kind of quality control you would hope and should implement in such studies.
To address this gap, we designed XCSITE 100. The device records both the stimulation current and voltage and sends the signal via bluetooth to the app that controls the stimulator. The resulting files are encrypted to ensure integrity of the study blind. But if there are any questions about what stimulation a given participant received, it is straightforward to trace back to the specific stimulation applied (including the quality of the electrode attachment which can be determined from the calculated resistance, remember Ohm's law...). We provide a decryption app which can be used on a desktop computer to unlock the files. We know of customers who assign a person not involved in the study (who is unblinded) to look at the recorded file after every single study visit to ensure that 100% of all stimulation were correct. With the tools provided with XCSITE 100, you will find this process very easy. If you want to go fancy and record the current and voltage trace with your own data acquisition system (perhaps at a high sampling rate or together with your EEG signals), we now have the PLUS module for you!
Just imagine being able to write in your method section "Stimulation current and voltage waveforms were independently verified for each stimulation session using the log files provided by the XCSITE 100 stimulator (Pulvinar Neuro, Chapel Hill, NC)."
Please reach out to us if you have any questions/comments (also please leave comments below!).
Next time, I will write about my thoughts on choosing the right study design for tDCS/tACS studies.
CSO Pulvinar Neuro