Neuronal Mechanisms In Pupil Dilation (What do Our Eyes Tell us About Our Brain Chemistry & Overall Health)

......The Eye's are the "Window to the Soul"...or the

Seat of the Soul ; which was it?

Well maybe there is some truth to that. You know though, I like factual information. Not casual-definitive re-debunking. So whilst this discussion may seem glamorous - I'm going to save that for a later time  - or for AMx ReBorN to pick up on ...or one of our other Philosopher's. 

.....

OK!

So our brain chemistry relates back to our eyes in many ways. 

Our brain neurotransmitter systems relay messages of iris-sphincter muscle closation/constriction or dilation...and of course, our food intake and level of fatty acids in our diet or blood stream impact this as well. 

However given the amount of drug and heavy metal exposure we have to deal with on the daily - the most RELEVANT aspects of this whole science are the CORE neuronal mechanisms involved in the almighty EYE's appearance.

   ....SEROTONIN AND PUPIL SIZE/DILATION

A Central study suggests., in a affirmative - surefire fashion - that...

5-HT1A serotonin receptor activation (presumably the 'autoreceptors' ; presynaptic) - causes miosis in HUMANS (not primates, not rats or rabbits folks!) - that means CONSTRICTION (pupil becomes smaller by 5-HT1A activation)...essentially; because SYMPATHETIC activity was referenced (a measure of nervous system excitation) - and autoreceptors DECREASE serotonin release; thus lowering overall excitation - the result is pupil constriction. 

In other words; the muscles and veins in other places are almost totally OPPOSITE to the EYE/IRIS - whereas serotonin and adrenaline may tighten/constrict arteries and blood flow elsewhere - in the EYE - serotonin and adrenaline both DILATE.

When your brain's REGULATORY mechanisms to CONTROL excess serotonin are activated (as with the anti-anxiety drug BUSPAR; which decreases serotonin) - the result is, with buspirone and others; pupil constriction...and also lower heart rate and blood pressure....

Thus it could be said - that if your  PUPILS are not overly dilated, or more on the constricted side - that you may have a healthier heart or trending towards LOW-ish blood pressure and CNS Activity!

           ACETYLCHOLINE AND PUPILS; Another Inverse Correlation to DiLation


A Hindawi Publication in the Journal of Ophthalmology observed that  SMOKING causes Pupil CONSTRICTION - now while this may not ALWAYS be the case; it is, in many chronic smokers a consistency and especially in acute smoking BINGES. Nicotine, the MAIN PSYCHOACTIVE substance in Cigarette's SELECTIVELY activates ONLY Nicotinic Acetylcholine Receptors.... under this observation - and along with other studies that ALSO confirm this on a more, molecular basis....brain scans yada Yada; nicotinic acetylcholine receptors are potent HUMAN PUPIL CONSTRICTORS....oh, and so do MUSCARINIC acetylcholine receptors; which are activated by nerve gases and such ...at such a high PERMEATING rate it is the equivalent of the bodybuilders SUPRAPHYSIOLOGICAL AMOUNTS OF STEROID INJECTION....nerve gases are basically ACETYLCHOLINE ON STEROIDS.....and therefore ......acetylcholine ; though it dilates other ARTERIES, though acetylcholine helps to maintain a normal blood pressure and ward off heart disease (in normal amounts) - it does CONSTRICT THUH EYE!~!


This is also in accordance/conformity with drugs like BUSPAR of the AZAPIRONE class ; which decrease serotonin ; thereby enhancing acetylcholine; thus again, coming back to set the STAGE for PUPIL CONSTRICTION...aren't they having fun, our pupils, I mean!?



Thus ultimately, higher cholinergic neurotransmission coupled with lower serotonin and lower adrenaline ultimately leads to more constricted pupils....and so, if you are PARASYMPATHETICALLY dominant; aka, a THINKER; the relaxed; sort of see everything for what it is LOGICAL type; MOST PROBABLY you will have constricted pupils..but if you are the type who is on EDGE in a constant LEE furious, revengeful, adrenaline HASTENED fashion - or who likes to shoot up movie theaters, then perhaps, your LITTLE PUPILS MAY. NOT.BE.SO.LITTLE....

PHYSIOLOGY OF ADRENERGIC RECEPTORS IN HUMANS

Distribution of alpha-1 adrenoceptor subtypes in RNA and protein in rabbit eyes