title: Recording human cortical population spikes non-invasively--An EEG tutorial.
abstract: BACKGROUND
  Non-invasively recorded somatosensory high-frequency oscillations (sHFOs) evoked by electric nerve stimulation are markers of human cortical population spikes. Previously, their analysis was based on massive averaging of EEG responses. Advanced neurotechnology and optimized off-line analysis can enhance the signal-to-noise ratio of sHFOs, eventually enabling single-trial analysis.
  
  
  METHODS
  The rationale for developing dedicated low-noise EEG technology for sHFOs is unfolded. Detailed recording procedures and tailored analysis principles are explained step-by-step. Source codes in Matlab and Python are provided as supplementary material online.
  
  
  RESULTS
  Combining synergistic hardware and analysis improvements, evoked sHFOs at around 600 Hz ('σ-bursts') can be studied in single-trials. Additionally, optimized spatial filters increase the signal-to-noise ratio of components at about 1 kHz ('κ-bursts') enabling their detection in non-invasive surface EEG.
  
  
  CONCLUSIONS
  sHFOs offer a unique possibility to record evoked human cortical population spikes non-invasively. The experimental approaches and algorithms presented here enable also non-specialized EEG laboratories to combine measurements of conventional low-frequency EEG with the analysis of concomitant cortical population spike responses.
authors.affiliation: Neurophysics Group, Department of Neurology, Campus Benjamin Franklin, Charite - University Medicine Berlin, Hindenburgdamm 30, 12203 Berlin, Germany; Bernstein Focus: Neurotechnology Berlin, Germany. Electronic address: gunnar.waterstraat@charite.de.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Waterstraat
authors.affiliation: Neurophysics Group, Department of Neurology, Campus Benjamin Franklin, Charite - University Medicine Berlin, Hindenburgdamm 30, 12203 Berlin, Germany; Bernstein Focus: Neurotechnology Berlin, Germany; Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany. Electronic address: c1tommaso.fedele@charite.de.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Fedele
authors.affiliation: Bernstein Focus: Neurotechnology Berlin, Germany; Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany. Electronic address: cmartin.burghoff@ptb.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Burghoff
authors.affiliation: Bernstein Focus: Neurotechnology Berlin, Germany; Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany.
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Scheer
authors.affiliation: Neurophysics Group, Department of Neurology, Campus Benjamin Franklin, Charite - University Medicine Berlin, Hindenburgdamm 30, 12203 Berlin, Germany; Bernstein Focus: Neurotechnology Berlin, Germany; Bernstein Center for Computational Neuroscience Berlin, Germany. Electronic address: dgabriel.curio@charite.de.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Curio
mesh_terms: D000328:Adult; D016477:Artifacts; D004569:Electroencephalography / Q000295:instrumentation* / Q000379:methods*; D005073:Evoked Potentials, Somatosensory; D006801:Humans; D008297:Male; D010812:Physical Stimulation / Q000379:methods; D012815:Signal Processing, Computer-Assisted; D059629:Signal-To-Noise Ratio; D012984:Software; D013003:Somatosensory Cortex / Q000502:physiology*
keywords: Evoked potentials; High-frequency oscillations; Single-trial analysis; Somatosensory system; Spatial filtering