Dissociable neural correlates of stimulation intensity and detection in somatosensation

Neuroimage. 2020 Aug 15:217:116908. doi: 10.1016/j.neuroimage.2020.116908. Epub 2020 May 6.

Abstract

Somatosensory stimulation intensity and behavioral detection are positively related, and both correlate with neural responses. However, it is still controversial as to what extent stimulus intensity and early somatosensory evoked potentials (SEP) predict detection and how these parameters interact with pre-stimulus brain oscillatory states, which also influence sensory processing. Here we investigated how early SEP components encode stimulation intensity, how pre-stimulus alpha- and beta-band amplitudes interact with SEPs, and which neural markers predict stimulus detection. To this end, we randomly presented electrical finger nerve stimulation with various intensities distributed along the individual psychometric response function (including catch trials) while recording the EEG. Participants reported stimulus presence on a trial-by-trial basis (one-alternative-forced-choice). For the lowest (imperceptible) intensities, participants showed zero (behavioral) sensitivity despite measurable early cortical processing reflected by the P50 component. The P50 amplitude scaled with increasing stimulation intensities but was not predictive of stimulus detection. Instead, detection was associated with the later negative N150 component, as well as with pre-stimulus lowered somatosensory alpha- and increased frontal beta-band amplitudes. Our results give evidence for a serial representation of stimulus intensity and detection, as reflected by the P50 and N150 amplitude, respectively. Furthermore, stimulus detection seems to depend on the current brain state, rendering upcoming stimulation being reportable or not.

Keywords: Baysian null-hypotheses testing; Event-related potentials; Pre-stimulus rolandic oscillations; Regularized logistic regression; Somatosensory detection; Subthreshold electrical stimulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Alpha Rhythm
  • Beta Rhythm
  • Electric Stimulation*
  • Electroencephalography
  • Evoked Potentials, Somatosensory / physiology*
  • Female
  • Fingers / innervation
  • Fingers / physiology
  • Humans
  • Male
  • Psychometrics
  • Psychomotor Performance
  • Reaction Time / physiology
  • Sensory Thresholds
  • Somatosensory Cortex / physiology
  • Young Adult