Flashing dreams and epilepsy = bad combination?
October 7, 2005 9:00 AM Subscribe
If you have epilepsy, do you have an attack if you dream about flashing lights? If not, why not?
I do not know of any scientifically valid way to ascertain the content of a person's dreams, so I cannot even imagine that this question could be answered in any kind of meaningful way.
In fact, I am not sure that experiences that are had in dreaming are similar to experiences that are had in waking. In waking, a patient might have a strobe light placed in front of him. Then, I walk over to the machine and press the 'start' button. The strobe light starts to pulse. The patient experiences time passing; as it does so, the light flashes on and off. Eventually the patient might feel an aura or may go into a seizure. Later, he might have a memory of this event. He might say, "I remember that I was seated and a strobe light was flashing."
However, I am not convinced that a patient in REM sleep, who wakes up and reports a dream that he was strobed by his neurologist, was having a serial experience over time like the one I described above. I think it's just as likely that whatever process happened in REM sleep created the memory or meme that he accessed as the memory of a dream, but did so in a non-serial way, possibly all at once. Whether you agree with me or not, you cannot prove that I am wrong; this is a non-falsifiable hypothesis until someone develops a 'dreamoscope' or some other way to objectively measure things like memories and dream contents.
That said: do epileptic seizures arise from REM sleep? Yes, they can.
posted by ikkyu2 at 12:46 PM on October 7, 2005
In fact, I am not sure that experiences that are had in dreaming are similar to experiences that are had in waking. In waking, a patient might have a strobe light placed in front of him. Then, I walk over to the machine and press the 'start' button. The strobe light starts to pulse. The patient experiences time passing; as it does so, the light flashes on and off. Eventually the patient might feel an aura or may go into a seizure. Later, he might have a memory of this event. He might say, "I remember that I was seated and a strobe light was flashing."
However, I am not convinced that a patient in REM sleep, who wakes up and reports a dream that he was strobed by his neurologist, was having a serial experience over time like the one I described above. I think it's just as likely that whatever process happened in REM sleep created the memory or meme that he accessed as the memory of a dream, but did so in a non-serial way, possibly all at once. Whether you agree with me or not, you cannot prove that I am wrong; this is a non-falsifiable hypothesis until someone develops a 'dreamoscope' or some other way to objectively measure things like memories and dream contents.
That said: do epileptic seizures arise from REM sleep? Yes, they can.
posted by ikkyu2 at 12:46 PM on October 7, 2005
Thoughts in general aren't really the same as perceptions are they? If I imagine someone's face I will get a jumble of impressions and feelings, not a photo.
posted by lunkfish at 2:57 PM on October 7, 2005
posted by lunkfish at 2:57 PM on October 7, 2005
Lunkfish, I do not know, but I don't think so.
We think that these photosensitive epilepsy folks, having perhaps an abnormality already in their level of GABA-ergic cortical inhibition, are susceptible to photic driving in the pyramidal cells of their occipital calcarine cortex (Brodmann area 17, easily distinguished on gross section by the white stripe of Gennari, representing the heavy myelination of the thalamocortical inputs to cortical layer IV of this particular bit of cortex.)
Basically, these cells either are processing first-order visual information or are idling; they tend already to synchronize when idling, first demonstrated by Hans Berger in the 1920s when he recorded a 10 Hz occipital dominant rhythm with his primitive electroencephalograph. When the strobe light produces input that synchronizes with their inherent rhythms, and given a deficit of cortical inhibition, their idle rhythm becomes prominent and increases in amplitude (photic driving) and can spread to other cortical areas, producing loss of consciousness and the typical findings of a generalized seizure.
In some studies, 1 to 1.5% of healthy persons can be susceptible to photic driving; the fraction who will seize with this stimulus is much lower.
During REM sleep, the eyes move around behind the closed lids, and an occipital dominant rhythm is also seen, but it tends to be less well organized than the waking occipital dominant rhythm, and it is almost always 1-2 Hz slower.
These things are very interesting to me and I wish I had a better answer to these sort of questions.
posted by ikkyu2 at 12:03 AM on October 8, 2005
We think that these photosensitive epilepsy folks, having perhaps an abnormality already in their level of GABA-ergic cortical inhibition, are susceptible to photic driving in the pyramidal cells of their occipital calcarine cortex (Brodmann area 17, easily distinguished on gross section by the white stripe of Gennari, representing the heavy myelination of the thalamocortical inputs to cortical layer IV of this particular bit of cortex.)
Basically, these cells either are processing first-order visual information or are idling; they tend already to synchronize when idling, first demonstrated by Hans Berger in the 1920s when he recorded a 10 Hz occipital dominant rhythm with his primitive electroencephalograph. When the strobe light produces input that synchronizes with their inherent rhythms, and given a deficit of cortical inhibition, their idle rhythm becomes prominent and increases in amplitude (photic driving) and can spread to other cortical areas, producing loss of consciousness and the typical findings of a generalized seizure.
In some studies, 1 to 1.5% of healthy persons can be susceptible to photic driving; the fraction who will seize with this stimulus is much lower.
During REM sleep, the eyes move around behind the closed lids, and an occipital dominant rhythm is also seen, but it tends to be less well organized than the waking occipital dominant rhythm, and it is almost always 1-2 Hz slower.
These things are very interesting to me and I wish I had a better answer to these sort of questions.
posted by ikkyu2 at 12:03 AM on October 8, 2005
Well,
As a physician, let me say this --
Definitely seizures have been induced by flashing lights, strobes and more during wakefulness.
However, it would seem exceedingly unlikely that in REM sleep cannot cause a seizure because of the cortical inhibition via locus ceroleus of the body's motor function. Said another way, a grand mal seizure by definition is likely not to occur during REM. However, it is possible for a petit mal/absence seizure -- but this does not case the phsyical "damage" associated with seizures as there is no associated motor/muscle movements.
Therefore, don't sweat it chap!
posted by bhenry at 7:48 AM on October 8, 2005
As a physician, let me say this --
Definitely seizures have been induced by flashing lights, strobes and more during wakefulness.
However, it would seem exceedingly unlikely that in REM sleep cannot cause a seizure because of the cortical inhibition via locus ceroleus of the body's motor function. Said another way, a grand mal seizure by definition is likely not to occur during REM. However, it is possible for a petit mal/absence seizure -- but this does not case the phsyical "damage" associated with seizures as there is no associated motor/muscle movements.
Therefore, don't sweat it chap!
posted by bhenry at 7:48 AM on October 8, 2005
The above comment's completely wrong, or at least it would be if it could be parsed.
The subcortical inhibition of normal motor activity during REM sleep has no effect on epileptic brain activity. Also, by the time a seizure generalizes, the findings of REM sleep (including the reduced muscle tone) will no longer be present.
I have recordings of seizures arising out of REM sleep. It's not usual, but it can happen.
posted by ikkyu2 at 8:25 AM on October 8, 2005
The subcortical inhibition of normal motor activity during REM sleep has no effect on epileptic brain activity. Also, by the time a seizure generalizes, the findings of REM sleep (including the reduced muscle tone) will no longer be present.
I have recordings of seizures arising out of REM sleep. It's not usual, but it can happen.
posted by ikkyu2 at 8:25 AM on October 8, 2005
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posted by gramcracker at 9:22 AM on October 7, 2005