Neural excitability and sensory input determine intensity perception with opposing directions in initial cortical responses

Elife. 2021 Oct 5:10:e67838. doi: 10.7554/eLife.67838.

Abstract

Perception of sensory information is determined by stimulus features (e.g., intensity) and instantaneous neural states (e.g., excitability). Commonly, it is assumed that both are reflected similarly in evoked brain potentials, that is, larger amplitudes are associated with a stronger percept of a stimulus. We tested this assumption in a somatosensory discrimination task in humans, simultaneously assessing (i) single-trial excitatory post-synaptic currents inferred from short-latency somatosensory evoked potentials (SEPs), (ii) pre-stimulus alpha oscillations (8-13 Hz), and (iii) peripheral nerve measures. Fluctuations of neural excitability shaped the perceived stimulus intensity already during the very first cortical response (at ~20 ms) yet demonstrating opposite neural signatures as compared to the effect of presented stimulus intensity. We reconcile this discrepancy via a common framework based on the modulation of electro-chemical membrane gradients linking neural states and responses, which calls for reconsidering conventional interpretations of brain potential magnitudes in stimulus intensity encoding.

Keywords: EEG; alpha; excitability; human; intensity perception; neuroscience; oscillations; somatosensory.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Electric Stimulation*
  • Electroencephalography
  • Evoked Potentials, Somatosensory / physiology
  • Humans
  • Male
  • Motor Cortex / physiology*
  • Perception
  • Peripheral Nerves / physiology*
  • Somatosensory Cortex / physiology*
  • Young Adult

Grants and funding

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.