Photostimulation

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Under photostimulation is understood in neurology , especially in the Epileptology a provocation method . During an EEG recording, the test person is “stimulated” with a flickering light with a rising and falling frequency from 4 to 20 Hz. In the case of sensitive people, it can be observed in the brain waveform that the electrical surface activity of the brain is increasingly synchronized (so-called “ photoparoxysmal reaction ”). This is shown in waves with ever higher amplitudes and shorter and shorter wavelengths, so-called "steep waves", also called "hypersynchronous activity" or "epilepsy-typical potentials" by other authors.

methodology

If only raw data is not stored digitally anyway, the EEG is derived in bipolar longitudinal rows in the darkened EEG room. The flash frequency is increased from 4 to 20 Hz over 30 s and reduced again to 4 Hz over the next 30 s. This is followed by stimulation for 30 s at 5, 10, 12, 15 and 20 Hz. Finally, irregular flashes (average frequency> 10 Hz) are used for 80 s. If a photoparoxysmal reaction occurs, the provocation should be stopped immediately, because otherwise such photostimulation can even trigger a seizure.

literature