system
Given the following post, respond as if you're commenting on Reddit:
human
Why do rapidly flashing lights / rapidly changing images cause epileptic seizures?

Nothing really to add here, just the question in the post.
gpt
First off, most people with epilepsy are not photosensitive.
   
Some types of epilepsy can be triggered by stimuli at a specific frequency. So in some cases, a person might be sensitive to lights flashing at a particular frequency. Another person might be sensitive to loud, rhythmic sounds at a particular frequency. 
  
**Short Answer :**
  
The same way any form of over-stimulation causes seizures.
  
The flashing lights cause the brain send out too many brainwaves at once. This results in a seizure.
  
This type of epilepsy is known as photosensitive epilepsy.
  
**Long Answer :** 
  
Photosensitive epilepsy results when a neural circuit somewhere in the brain resonates with a sensory input, and the brain fails to keep that resonance under control.
  
 Flashing lights tend be a very powerful pattern of stimulation as they can activate both on and off retinal ganglion cells (cells in the retina that respond to changes int the state of light). Scientists who study the visual cortex will often use a drifting grating of black and white bars to elicit a strong reliable response. The reason why some epileptics might respond to this stimuli probably has to do with how those signals are handled beyond the retina, in the thalamus or cortex. What happens at that level is hard to answer. Broadly speaking these areas are wired or have properties that make them poor handlers of highly synchronous stimuli. One possibility being recurrent excitation coupled to low inhibition could cause an epileptic like state in the brain.