In terms of and its effects on brain cells, or neurons, there is little evidence to suggest that any of the active ingredients in the marijuana plant administered at doses appropriate for human consumption have neurotoxic effects.
The fact that these receptors are located all over the body is part of the reason why marijuana has been found to be useful for so many different medical conditions.
Marijuana: Effects of Weed on Brain and Body
Specifically in the case of seizures, there is preliminary research which shows that the cannabinoid, cannabidiol or CBD, raises the threshold for seizure activity within the brain , and thus providing hope to many parents of children with intractable seizure disorders. There is also some preliminary research which show that other cannabinoids within the plant . However, much more research needs to be done in order to make definitive claims on the medical benefits.