Single-trial variability of simultaneous spinal and supraspinal responses during cognitive tasks assessed using mutual information analysis.

F. G. ARGUISSAIN; J. A. BIURRUN MANRESA; O. K. ANDERSEN; C. D. MØRCH

Vienna

Congreso; 9th Congress of the European Pain Federation EFIC; 2015

European Pain Federation EFIC

Background and aims: Repeated physiological measures are variable, but the source of such variability is notoriously difficult to pin down. Here we aimed to quantify the trial-by-trial variabilities of two biological responses elicited by one intense somatosensory stimulus: the spinal nociceptive withdrawal reflex (NWR) and the brain somatosensory-evoked potential (SEP).Methods: We electrically stimulated the foot sole to elicit both the NWR, measured by EMG on the tibialis anterior muscles, and the SEP, measured by scalp EEG at the vertex. In different stimulation blocks subjects were asked to either focus on the stimuli (?attention? condition) or perform a visual Stroop test (?distraction? condition). The condition effect on both single-trial SEPs and NWR was analyzed using linear mixed model (LMM), for each waveform timepoint. The across-trial variability of SEPs and NWR in each condition was quantified using Mutual Information (MI). Differences in MI between the two conditions were assessed by repeated measures ANOVA.Results: the NWR had smaller amplitude during attention compared to distraction.Conclusions: NWR are larger and less variable during distraction.