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posterior superior parietal lobe - Dissociatives

Ham-milton

Ham-milton

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I've read that damage to the "posterior superior parietal lobe" results in the inability to distinguish where the self ends and the world begins, thus bumping and falling into things with high frequency.

It's also been observed that blood flow to this region is decreased with meditation, and that this may result in the feelings of "oneness" associated with deep meditation.

Has anyone looked into the effect of dissociatives or high dose psychedelics on this region?
 
You're idea of functional significance is pretty close. Search using the posterior/caudal superior parietal LOBULE (using the word lobe instead will cut your matches down to that one hippied out article, as anatomists are sticklers like grammar freaks).

the SPL receives information from the somatosensory association cortex (mixes a bunch of the info from touch modalities mainly with visual sensory... not including the spinothalamic temp/pain/wide-range nociceptive senses). This obviously well explains the effects of lesioning on distinguishing one's boundaries. It's role in recognition and interpretation is usually studied like in:

http://www.pnas.org/content/92/24/11180.abstract (refers to 'body-in-space')
http://jn.physiology.org/cgi/content/abstract/76/3/2042 (refers to mental transformations)

I would however say the best place to start forming a hypothesis to your question is to find some whole-brain fMRI imaging (and any other high-res realtime imaging... MEG would be fantastic) studies of the drugs the phenomena reminds you of. Look at SPL, afferent and efferent areas :P. If you post the studies here I can help you with the extrapolation.

If you cannot find imaging studies, then I would just start with finding out the relative density of the important receptors for the drugs to see whether it's feasible for them to cause a pronounced change/effect in the SPL (or even the source and destination of signal).

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ps - While we're jumping to conclusions based on experiences... Simultagnosia (inability to perceive more than one object at a time, even is co-located) is associated with lesions in our area. It almost seems like the 'focus on the candle' (and other one object) approaches to entering meditation might be a means of mimicking hypofunction in this area, and as a result playing with the SPL's effects on internal state awareness...
 
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certainly an interesting area an oddly these altered states I assume have no evolutionary function (just the end result of the 'narrowing' of functional pathways) even though they can be seen to now be exploited to pro-actively enhance our 'experience' and even translate to functional exploit for some i suppose
 
I disagree. I know people who have claimed to have 'psychic' experiences off lysergamides, dont know about dmt/ibogaine tho. I never paid much mind to these claims but I have and I have friends who have undoubtably had these experiences off dissociatives. I believe(and have no neuro/pharmacology knowledge to back this up) that when these drugs shut down our glutamergic pathways they can possibly(indirectly) open up others that dont normally use. Perhaps it maybe a 'de'evolutionary thing like how many animals have abilities to communicate that we dont understand-an almost psychic ability of knowledge/understanding that is more intuned to the world around them. Some claim that following Near Death Experiences they have developed psychic abilities. While some may be crazy, it has clearly worked for others. During a NDE the brain releases it's own NMDA antagonists aswell as DMT. This conjunction is medically proven to be very protective/beneficial to the brain
 
I know people who have claimed to have 'psychic' experiences off lysergamides
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I think that it's more likely that it's due to things likr sensory lags or other descrpancies in processing sensory information (which both psychedelics & dissociatives play havoc with). Well in my mind that fits with the increased incidence of things like deja vu inder the influence of such drugs
 
During a NDE the brain releases it's own NMDA antagonists aswell as DMT. This conjunction is medically proven to be very protective/beneficial to the brain
Click to expand...

That's entirely conjecture. There is no evidence for this. Strassman hypothesis repeatedly ad infinitum until it was accepted as truth.
 
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