Simultaneous Assessment of Spinal and Supraspinal Activity during Experienced Pain: An Alternative Approach using Information Theory

The nociceptive withdrawal reflex (NWR) and the somatosensory evoked potentials (SEPs) are two physiological responses that reflect spinal and supraspinal sensory processing, respectively. Although they can be elicited synchronously, its concurrent use in pain research is limited. Still, its assessment has mainly focused on the averaged signals across trials. Yet, an increasing body of work suggests that across-trial variability should be considered as a functional property of the nervous system that could index modulatory and clinical conditions.
In this Ph.D. project the aims were to study the viability of using single-trial (ST) features from both NWR and SEPs and to introduce Information Theory (IT) as a viable approach to integrate ST data and to characterize signal variability of these two signals to provide more insight about pain processing mechanisms.
Results emphasized the impact of selecting different ST detection methods. Moreover, it was shown that the IT framework can be used to quantify the information carried jointly by NWR and SEPs. Finally, it was found that cognitive modulatory tasks were accompanied by changes in the variability of the NWR and SEPs, and this was reflected in the information content across conditions.
In conclusion, the IT framework is a suitable and promising methodology to quantify the relation between spinal and supraspinal activity in pain research.