Non-invasive single-trial detection of variable population spike responses in human somatosensory evoked potentials

Clin Neurophysiol. 2016 Mar;127(3):1872-8. doi: 10.1016/j.clinph.2015.12.005. Epub 2015 Dec 15.

Abstract

Objective: Somatosensory evoked potentials (SEPs) around 600 Hz ('σ-bursts') are correlates of cortical population spikes. Recently, single-trial σ-bursts were detected in human scalp EEG using 29-channel low-noise recordings in an electromagnetically shielded room. To achieve clinical applicability, this study aimed to establish a protocol using only 8 EEG channels in an unshielded environment and to quantify the variability of σ-bursts.

Methods: Median nerve SEPs were recorded in 10 healthy subjects using a custom-built low-noise EEG amplifier. A detection algorithm for single-trial σ-bursts was trained as combination of spatio-temporal filters and a non-linear classifier. The single-trial responses were probed for the presence of significant increases of amplitude and variability.

Results: Single-trial σ-burst detection succeeded with Detection Rates and Positive Predictive Values above 80% in subjects with high SNR. A significant inter-trial variability in the amplitudes of early low-frequency SEPs and σ-bursts could be demonstrated.

Conclusions: Single-trial σ-bursts can be detected on scalp-EEG using only 8 EEG channels in an electromagnetically disturbed environment. The combination of dedicated hardware and detection algorithms allows quantifying and describing their variability.

Significance: The variability of population spikes in the human somatosensory cortex can be traced non-invasively in a clinical setting.

Keywords: Evoked potentials; Excitability; High-frequency oscillations; Single-trial detection; Somatosensory system; Variability.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology*
  • Adult
  • Electric Stimulation / methods
  • Electroencephalography / methods*
  • Evoked Potentials, Somatosensory / physiology*
  • Female
  • Humans
  • Male
  • Median Nerve / physiology
  • Middle Aged
  • Somatosensory Cortex / physiology*
  • Young Adult