How to make calibration less painful -- a proposition of an automatic,
reliable and time-efficient procedure.
Abstract
In behavioural and neurophysiological pain studies, multiple types of
calibration methods are used to quantify the individual pain stimuli.
Often studies lack calibration procedure implementation, have a vague
protocol description, do not provide quality quantification, and omit
required control for gender pain differences, hampering study repetition
and interexperimental comparisons. Moreover, typical calibration
procedures require a high number of stimulations which may cause
participants’ discomfort and stimuli habituation. To overcome those
shortcomings, we present an automatic calibration procedure with a novel
stimuli estimation method for intra epidermal stimulation adjusted to
the magnetoencephalography environment. We provide an in-depth data
analysis of the collected self-reports from seventy healthy volunteers
(37 males) and propose a method based on a dynamic truncated linear
regression model (tLRM). We compare its estimates for the sensation (t),
and pain (T) thresholds, as well as for the mid-pain stimulation (MP),
with those calculated using a traditional estimation method and standard
linear regression models. Compared to the other methods, tLRM exhibits
higher R2 and requires 36% fewer stimuli application and has
significantly higher t and lower T and MP intensities. Regarding sex
differences, t and T were found to be lower for females compared to
males, regardless of the estimation method. The proposed tLRM method
quantifies the calibration procedure quality, minimizes its duration and
invasiveness, as well as provides validation of linearity between
stimuli intensity and subjective scores, making it an enabling technique
for further studies. Moreover, our results highlight the importance of
control for gender in pain studies