title: Chirp-modulated visual evoked potential as a generalization of steady state visual evoked potential.
abstract: Visual evoked potentials (VEPs) are of great concern in cognitive and clinical neuroscience as well as in the recent research field of brain-computer interfaces (BCIs). In this study, a chirp-modulated stimulation was employed to serve as a novel type of visual stimulus. Based on our empirical study, the chirp stimuli visual evoked potential (Chirp-VEP) preserved frequency features of the chirp stimulus analogous to the steady state evoked potential (SSVEP), and therefore it can be regarded as a generalization of SSVEP. Specifically, we first investigated the characteristics of the Chirp-VEP in the time-frequency domain and the fractional domain via fractional Fourier transform. We also proposed a group delay technique to derive the apparent latency from Chirp-VEP. Results on EEG data showed that our approach outperformed the traditional SSVEP-based method in efficiency and ease of apparent latency estimation. For the recruited six subjects, the average apparent latencies ranged from 100 to 130 ms. Finally, we implemented a BCI system with six targets to validate the feasibility of Chirp-VEP as a potential candidate in the field of BCIs.
authors.affiliation: Department of Biomedical Engineering, Tsinghua University, Beijing, People's Republic of China.
authors.forename: Tao
authors.initials: T
authors.lastname: Tu
authors.forename: Yi
authors.initials: Y
authors.lastname: Xin
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Gao
authors.forename: Shangkai
authors.initials: S
authors.lastname: Gao
mesh_terms: D000328:Adult; D004569:Electroencephalography / Q000379:methods*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D006801:Humans; D008297:Male; D010775:Photic Stimulation / Q000379:methods*; D011930:Reaction Time / Q000502:physiology*; D014584:User-Computer Interface; D014793:Visual Cortex / Q000502:physiology*