In neurology and neuroscience research, steady state visually evoked potentials (SSVEP) are signals that are natural responses to visual stimulation at specific frequencies. This technique is used widely with electroencephalographic research regarding vision and attention.
What is BCI Ssvep?
Brain-computer interfaces (BCI) are communication systems that allow people to send messages or commands without movement. BCIs rely on different types of signals in the electroencephalogram (EEG), typically P300s, steady-state visually evoked potentials (SSVEP), or event-related desynchronization.
What is P300 BCI?
A P300 brain-computer interface (BCI) is a paradigm, where text characters are decoded from event-related potentials (ERPs). In a popular implementation, called P300 speller, a subject looks at a display where characters are flashing and selects one character by attending to it.
Why is Ssvep called steady state?
SSVEPs have long been considered a steady-state response resulting from purely oscillatory components phase locked with the stimulation source, matching the stimulation frequency and its harmonics.
What is an event related brain potential?
Event-related potentials (ERPs) are very small voltages generated in the brain structures in response to specific events or stimuli (Blackwood and Muir, 1990). Event-related potentials can be elicited by a wide variety of sensory, cognitive or motor events.
How does the P300 work?
The P300 wave is an event-related brain potential measured using electroencephalography (EEG). P300 refers to a spike in activity approximately 300ms following presentation of the target stimulus, which is alternated with standard stimuli to create an ‘oddball’ paradigm, which is most commonly auditory.
How does a P300 speller work?
P300 speller is a communication tool with which one can input texts or commands to a computer by thought. The amplitude of the P300 evoked potential is inversely proportional to the probability of infrequent or task-related stimulus.
Is Ssvep an ERP?
The major difference between the ERP and SSVEP is that ERPs are responses to individual stimuli, whereas SSVEPs are responses to the whole stimulation period. Because of this characteristic, the SSVEP approach has often been used in recent studies on face processing10,11,12,16.
What are P300 waves?
The P300 wave is a positive deflection in the human event-related potential. It is most commonly elicited in an “oddball” paradigm when a subject detects an occasional “target” stimulus in a regular train of standard stimuli.
What do event-related potentials tell us?
Event-Related Potentials (ERPs) An ERP measures voltage changes in the brain that follow (or precede) the onset of specific visual, auditory, or other sensory stimuli, as well as cues signaling motor preparation, motor execution, or covert mental operations (e.g., imagery).
Why are event-related potentials important?
Relative to behavioral measures Compared with behavioral procedures, ERPs provide a continuous measure of processing between a stimulus and a response, making it possible to determine which stage(s) are being affected by a specific experimental manipulation.
What does SSVEP stand for?
Among them, steady state visual evoked potentials (SSVEPs) are particularly attractive due to high signal to noise ratio (SNR) [ 6] and robustness [ 7 ].
How does SSVEP work in OpenViBE?
In OpenViBE, we use the computer screen as the flickering device. Thus, a flickering object (or “target”) is represented by a shape which changes color at a constant frequency. In order for the SSVEP to work, this change of color must occur at precise intervals. It is thus necessary to redraw the targets in a synchronized way with the screen.
Where to place the electrodes in SSVEP scenarios?
The SSVEP scenarios use Common Spatial Pattern (CSP) spatial filter to select the best characteristics automatically. This means that you can place the electrodes on any part of the scalp in the occipital area. Good results were measured with electrodes Oz, O1, O2, CPz, POz and Iz.
What is steady-state visual-evoked potential (VEP)?
NB: Document concerns OpenViBE >= 0.18.0. Steady-State Visual-Evoked Potential is a brain response induced by a visual stimulus, flickering at a constant frequency between approximatively 6 and 100Hz. The response manifests itself as an increase in amplitude of the stimulated frequency.
