In neurology and neuroscience research, steady state visually evoked potentials (SSVEP) are signals that are natural responses to visual
stimulation
Stimulation is the encouragement of development or the cause of activity generally. For example, "The press provides stimulation of political discourse." An interesting or fun activity can be described as "stimulating", regardless of its physica ...
at specific
frequencies
Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...
. When the
retina
The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...
is excited by a visual stimulus ranging from 3.5
Hz to 75 Hz, the brain generates electrical activity at the same (or multiples of) frequency of the visual stimulus.
This technique is used widely with
electroencephalographic
Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neocortex ...
research regarding vision and attention. SSVEPs are useful in research because of the excellent
signal-to-noise ratio
Signal-to-noise ratio (SNR or S/N) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. SNR is defined as the ratio of signal power to the noise power, often expressed in deci ...
and relative immunity to artifacts.
[K. E. Misulis, Spehlmann's Evoked Potential Primer, Butterworth-Heinemann, Boston, Mass, USA, 1994.] SSVEPs also provide a means to characterize preferred frequencies of neocortical dynamic processes. SSVEP is generated by stationary localized sources and distributed sources that exhibit characteristics of wave phenomena.
See also
*
Evoked potential
References
Sources
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* {{cite journal , pmid=28334175 , doi=10.1093/cercor/bhx043 , volume=1-15 , issue=4 , pages=1297–1311 , title=Attenuated Fast Steady-State Visual Evoked Potentials During Human Sleep , year=2017 , journal=Cereb. Cortex , author1=Sharon O , author2=Nir Y, doi-access=free
Perception
Cognitive neuroscience
Evoked potentials
Electroencephalography