Authors: Jason Satel, Ross Story, Raymond M. Klein
Steady-state visual evoked potentials (SSVEPs) are scalp recorded oscillatory brain potentials associated with visual stimuli flickering at specific frequencies. These electrophysiological responses originate in primary visual cortex and have a sinusoidal waveform with the same temporal frequency as the stimuli. Previous work has shown that the amplitude of the SSVEP signal associated with a flickering stimulus is substantially increased when the stimulus is being attended. The dynamics of attentional mechanisms can thus be investigated by analyzing the SSVEP signals associated with flickering stimuli presented at different locations on a computer screen in attentional cueing paradigms. To extract the signal, processing of short samples of noisy signal to extract the power at the frequencies of interest is essential. In a clinical context, SSVEPs have proved useful as a diagnostic tool for disorders such as Parkinson’s, epilepsy, and schizophrenia. Furthermore, the attentional modulation of SSVEP signals can be exploited in order to control brain-computer interfaces in various clinical (e.g., to provide ‘locked-in’ patients with amyotrophic lateral sclerosis [ALS] a means of controlling aspects of their environment without muscle movements) and industrial (e.g., remote control of robotics) domains. Here, we have conducted two pilot experiments to investigate the association of SSVEP signals with mechanisms of inhibitory cueing. We propose that this novel technique could be used to examine the temporal dynamics of such inhibitory mechanisms in a manner that is not possible with traditional event-related potential (ERP) techniques and present further experimental designs that continue to investigate this issue.
Keywords: steady-state visual evoked potentials; attentional modulation; inhibition of return; brain-computer interfaces.