Fluorescent tube light evokes flicker responses in visual neurons.

Single neurons in the cat visual system respond distinctly to the temporal information present in light from fluorescent tubes driven by 50 or 60 Hz alternating current. Despite the resulting flicker frequencies of 100 or 120 Hz all retinal and most thalamic neurons show strong phase locking of the neuronal responses to the modulation of fluorescent tube light. Some retinal ganglion cells have not yet reached their critical flicker fusion frequency under such conditions. Though usually beyond perception, the frequency and depth of modulation of artificial light thus might well play a role in biological light effects.