title: Frequency-modulated steady-state visual evoked potentials: a new stimulation method for brain-computer interfaces.
abstract: BACKGROUND
  Steady-state visual evoked potentials (SSVEPs) are widely used for brain-computer interfaces. However, users experience fatigue due to exposure to flickering stimuli. High-frequency stimulation has been proposed to reduce this problem. We adapt frequency-modulated (FM) stimulation from the auditory domain, where it is commonly used to evoke steady-state responses, and compare the EEG as well as behavioral flicker perceptibility ratings.
  
  
  METHODS
  We evoke SSVEPs with a green light-emitting diode (LED) driven by FM signals.
  
  
  RESULTS
  FM-SSVEPs with different carrier and modulation frequencies can reliably be evoked with spectral peaks at the lower FM sideband. Subjective perceptibility ratings decrease with increasing FM carrier frequencies, while the peak amplitude and signal-to-noise ratio (SNR) remain the same.
  
  
  CONCLUSIONS
  There are neither amplitude nor SNR differences between SSVEPs evoked rectangularly, sinusoidally or via FM. Perceptibility ratings were lower for FM-SSVEPs with carrier frequencies of 20Hz and above than for sinusoidally evoked SSVEPs.
  
  
  CONCLUSIONS
  FM-SSVEPs seem to be beneficial for BCI usage. Reduced flicker perceptibility in FM-SSVEPs suggests reduced fatigue, which leads to an enhanced user experience and performance.
authors.affiliation: Experimental Psychology Lab, Department of Psychology, Center for Excellence 'Hearing4all', European Medical School, University of Oldenburg, 26111 Oldenburg, Germany.
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Dreyer
authors.affiliation: Experimental Psychology Lab, Department of Psychology, Center for Excellence 'Hearing4all', European Medical School, University of Oldenburg, 26111 Oldenburg, Germany; Research Center Neurosensory Science, University of Oldenburg, 26111 Oldenburg, Germany. Electronic address: christoph.herrmann@uni-oldenburg.de.
authors.forename: Christoph S
authors.initials: CS
authors.lastname: Herrmann
mesh_terms: D000328:Adult; D062207:Brain-Computer Interfaces; D004569:Electroencephalography / Q000379:methods*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation / Q000379:methods*; D055815:Young Adult
keywords: Amplitude modulation; Brain–computer interface (BCI); EEG; Frequency modulation; Light-emitting diode (LED); Steady-state visual evoked potential (SSVEP)