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songbird36
29 Apr 2006, 12:21 AM
I've been reading an interesting book which describes the different neurochemistry of Introverts (25% of population) and Extraverts (75%), and explains many of the different traits and needs exhibited by both.

It;'s been shown on PET scans that Is use different neural pathways to Es when engaged in almost any type of activity (including relaxation). During one study a group of identified Es and Is were asked to lie down and relax, and a PET scan was used to measure blood flow to the brain and the pathways it followed.

The Is had *more* bloodflow to the brain during relaxation than Es, indicating more internal stimulation. Also, the Is and Es' blood travelled along different pathways - the I pathway was found to be more complex, and flowed to areas of the brain associated with remembering, problem solving and planning.
The Es blood flowed on a more direct route to areas of the brain where sensory processing occurs. This confirmed the researchers' suspicion that the Es in the study were focused on what was happening around them in the lab, and were engaged in sensory processing.

The pathway used by Extraverts is activated by the chemical Dopamine. Dopamine is a powerful neurotransmitter, most closely associated with movement, attention, alert states, and learning. Too much dopamine in the brain causes hallucinations and paranoia, and too little causes depression, lethargy and misery. Having the right amount of Dopamine is critical to everyone.

It has been found that Extraverts have a low sensitivity to Dopamine (require more to get the desired effect). They require Adrenaline, which is released from the sympathetic nervous system, and makes more Dopamine in the brain. This explains why Es need more stimulation/thrill/activity, to feel good, and why they seek variety.

Introverts are highly sensitive to Dopamine - too much of it and they can feel overstimulated. Is rely on a different neurotransmitter, acetylcholine, on their dominant neural pathway. Acetylcholine affects attention and learning, influences the ability to sustain a calm, alert feeling and to utilise long term memory stores, and stimulates a good feeling when thinking or feeling emotion. Introverts require a lower level of Dopamine, and a good level of acetylcholine, to leave them calm and free of depression or anxiety. Too much activity/stimulation can leave Is in Dopamine "overload", and give them a feeling of exhaustion.

SHORTER EXTRAVERT NEURAL PATHWAY

Stimulation ascends the spinal cord and enter reticular activating system in brain stem - data enters the Hypothalamus (thirst/temperature/appetite) - this switches on the "Full Throttle" system in Extraverts - Stimulii are sent to POSTERIOR THALAMUS (a relay station which amplifies the stimuli and sends them to amygdala) - Amygdala is the emotional centre (associated with the actions in the motor area, in extraverts) - Stimuli transferred to Temporal and moror area (movement connects to short term memory access, and to the center for learning and processing sensory and emotional stimuli).

LONGER INTROVERT NEURAL PATHWAY

Stimuli enter Reticular activating system above brain stem - this system is less active in Introverts - transferred to Hypothalmus where the data is interpreted and the brain placed on "Throttle down" in Introverts - Data sent to ANTERIOR THALAMUS (relay station which turns sensory signals down in Introverts) - Data sent to Broca's Area (speech area where internal monologue is activated) - Data sent to Frontal lobe (thinking, planning, learning) - Data sent to Hippocampus (relayed to long term memory including environmental awareness) - Data sent to Amygdala (emotional centre where feelings are attached to thoughts, in Introverts).

ptGatsby
29 Apr 2006, 12:31 AM
If I vs E is based on MBTI, I believe the number of E:I is roughly 50:50, normally considered a maximum of 55:45.

Otherwise, very interesting!

Neppy
29 Apr 2006, 12:52 AM
Very nice post! It's a good explanation.

songbird36
29 Apr 2006, 12:55 AM
Another interesting point to ponder is that Extraverts can apparently access short-term memory areas of the brain more readily than Introverts, because of their faster and less complicated pathway. This could explain why an Introvert will often "grope" for a word in conversation or in a group discussion, or may have to think on an issue for longer before responding in appropriate language.

charred_heart
29 Apr 2006, 03:20 AM
very interesting

rivercrow
29 Apr 2006, 02:38 PM
What are you reading?

joft
29 Apr 2006, 03:42 PM
i read pretty much the same thing in "the introvert advantage", some dopey book written by an introverted psychologist

abathur
29 Apr 2006, 09:59 PM
If I vs E is based on MBTI, I believe the number of E:I is roughly 50:50, normally considered a maximum of 55:45.

Otherwise, very interesting!

Depends on what stats you're quoting. The Kiersy-Bates study in 64 established a 75:25 preference for E:I as well as S:N.

I don't know the methods for all of these but it wouldn't surprise me if the results weren't very statistically valid and don't generalize well. For example, the study (98 I think?) citing the 50% numbers is pulling its 3000 person sample randomly from 16000 taken tests, yet, a correlation has been shown between type and interest in even taking the test, so any study that relies on randomly selecting test results is going to have this statistical bias, inherently.

Various studies are all over the place so I'm not inclined to give them a lot of credit until we're really working with more than one study actually using statistically random population samples with high response rates and coming up with something pretty similar.

songbird36
1 May 2006, 11:01 AM
i read pretty much the same thing in "the introvert advantage", some dopey book written by an introverted psychologist

That is the book. Some parts are dopey yeah, but the neurochemistry stuff is intriguing.

Stoic
1 May 2006, 11:34 AM
All I know is that we have more neural activity in our frontal lobes (I'm pretty sure). But in any case, that's a call for celebration nonetheless.

Jasz
1 May 2006, 01:51 PM
If I vs E is based on MBTI, I believe the number of E:I is roughly 50:50, normally considered a maximum of 55:45.

Otherwise, very interesting!

reveal your sources, i have a hard time believing that E's and I's are so evenly spread

Jasz
1 May 2006, 03:06 PM
The pathway used by Extraverts is activated by the chemical Dopamine. Dopamine is a powerful neurotransmitter, most closely associated with movement, attention, alert states, and learning. Too much dopamine in the brain causes hallucinations and paranoia, and too little causes depression, lethargy and misery. Having the right amount of Dopamine is critical to everyone.

It has been found that Extraverts have a low sensitivity to Dopamine (require more to get the desired effect). They require Adrenaline, which is released from the sympathetic nervous system, and makes more Dopamine in the brain. This explains why Es need more stimulation/thrill/activity, to feel good, and why they seek variety.

Introverts are highly sensitive to Dopamine - too much of it and they can feel overstimulated. Is rely on a different neurotransmitter, acetylcholine, on their dominant neural pathway. Acetylcholine affects attention and learning, influences the ability to sustain a calm, alert feeling and to utilise long term memory stores, and stimulates a good feeling when thinking or feeling emotion. Introverts require a lower level of Dopamine, and a good level of acetylcholine, to leave them calm and free of depression or anxiety. Too much activity/stimulation can leave Is in Dopamine "overload", and give them a feeling of exhaustion.

very interesting

does the book also tell you how to get the right cocktail
of dopamine and acetylcholine to get the best of both worlds?

headfonez
1 May 2006, 04:10 PM
so do the nerual paths make an introvert an introvert, or is it his/her personality?

Can I be an extravert with the nerual pathways of an introvert?

songbird36
2 May 2006, 12:58 AM
so do the nerual paths make an introvert an introvert, or is it his/her personality?

Can I be an extravert with the nerual pathways of an introvert?

No, the point is that E and I brains are configured differently from birth. Is have a longer sensory processing pathway, which explains the "stimulus fatigue" Is often experience after a much lower level of external activity than Es can cope with.

ptGatsby
10 Apr 2007, 06:18 PM
reveal your sources, i have a hard time believing that E's and I's are so evenly spread

*sigh* This will be, roughly, my post #10 on this topic. :banghead:

http://www.capt.org/mbti-assessment/estimated-frequencies.htm

There is no larger database of MBTI results in the world, far as I know.

Jasz
10 Apr 2007, 06:31 PM
*sigh* This will be, roughly, my post #10 on this topic. :banghead:

http://www.capt.org/mbti-assessment/estimated-frequencies.htm

There is no larger database of MBTI results in the world, far as I know.

damn, that is quite different than other stats such as kiersey's. particularly interesting (i.e. different from my expectations) are:

1. E and I rather evenly spread (i thought E's were leading 2:1)
2. J more prevalent than expected (i thought it was rather balanced)

ptGatsby
10 Apr 2007, 06:37 PM
damn, that is quite different than other stats such as kiersey's. particularly interesting (i.e. different from my expectations) are:

1. E and I rather evenly spread (i thought E's were leading 2:1)
2. J more prevalent than expected (i thought it was rather balanced)

I'll offer the same challenge that I offer everyone else; Find the original - the very first claim - that E's were that dominant. It took me weeks to find it, and it wasn't online. (FWIW, it was done a very long time ago. That was before any real methodology had been applied to MBTI research.) I found that search vastly changed the way I viewed my own certainties on the information I depended on.

I have yet to come across a better example of living memory ever. Seriously; search for Extrovert 75% or Introvert 25%. It's everywhere.

Jasz
10 Apr 2007, 07:00 PM
I'll offer the same challenge that I offer everyone else; Find the original - the very first claim - that E's were that dominant. It took me weeks to find it, and it wasn't online. (FWIW, it was done a very long time ago. That was before any real methodology had been applied to MBTI research.) I found that search vastly changed the way I viewed my own certainties on the information I depended on.

I have yet to come across a better example of living memory ever. Seriously; search for Extrovert 75% or Introvert 25%. It's everywhere.

i think it was that heretic keirsey

bluebell
11 Apr 2007, 10:28 AM
Fascinating. I'll add that to my model of human behaviour. And think about it. Slowly of course.


i read pretty much the same thing in "the introvert advantage", some dopey book written by an introverted psychologist

So what's the rest of the book like? I was going to track it down cos the neuroscience stuff sounded really interesting, but if the rest of the book is a bit airy-fairy not sure I can be bothered.

kuranes
29 Jul 2009, 07:30 PM
One recent theory explains the neurochemistry of people who are slow to trust - naturally there are skeptics and its still being studied etc. blah blah
http://www.sciencedaily.com/releases/2008/07/080722090555.htm

http://www.sciencedaily.com/releases/2007/11/071107074321.htm

http://www.scientificamerican.com/blog/60-second-science/post.cfm?id=love-hormone-may-also-help-us-recog-2009-01-07