
Practical Facts about the Human Brain - LeonW
https://leowid.com/brain-facts/
======
Isamu
I wish people would be more skeptical about their recall of memories.

In particular I wish people would stop thinking their memories are especially
accurate if they were especially "vivid".

[https://en.wikipedia.org/wiki/Flashbulb_memory](https://en.wikipedia.org/wiki/Flashbulb_memory)

~~~
DanielFlower
I agree. Memory biases may either enhance or impair the recall of memory, or
they may alter the content of what we report remembering.

There are many memory biases including the humor effect, positivity effect and
the generation effect.

The humor effect states that humorous items are more easily remembered than
non-humorous ones.

Positivity effects states that older adults favor positive over negative
information in their memories.

Generation effect states that self-generated information is remembered best.

~~~
zdragnar
How universal are these biases? Anecdotally, I feel as though i have a
stronger recall of negative experiences than equivalently good ones. If that
is a thing, i wonder if it might be due to, or perhaps a cause of, depression.

~~~
lr4444lr
I think the better question to ask is, what _kind_ of memory? Research I
cannot conveniently find at the moment shows that raw declarative memory is
improved under trauma. For example, most people who were old enough,
nationwide, can recall where they were and what they were doing on 9/11\.
Other kinds of memory, like skill automating (e.g. playing the chords
effortlessly on a guitar or mastering the core grammar of a language) are much
harder to do when you're under stress.

~~~
AndreasM
Interestingly, though, it often turns out that recalling "where they were and
what they were doing on 9/11" is very often wrong. And that when you're wrong,
you're more certain you're right.

Malcolm Gladwell did a very interesting podcast episode on that:
[http://revisionisthistory.com/episodes/24-free-brian-
william...](http://revisionisthistory.com/episodes/24-free-brian-williams)

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LeonW
Hi everyone, Leo here. I feel grateful for the HN community's response to this
post. I only emerged recently to the "real world" again and feel still some
hesitation and fear around showing a much more vulnerable part of myself with
the work I do now. (Building marketing software was fun too!) So yeah, just
want to say thanks and would love to discuss anything this sparks.

~~~
joe_the_user
1) "80% of your body’s signals are sent to the brain from the body and only
20% the other way around."

This is pretty interesting. The idea of not attempt to "command" the body but
work with the body and unconscious process is common in a wide variety of
martial arts and healing art modalities (Alexander Technique, Qigong,
hypnosis, etc).

2) "When your amygdala is active, you can’t have empathy for others"

Unfortunately, this statement seems to suffer from the weakness of popular
psychology expositions - a series of fairly pat cause-and-effect statement
when the causes of virtually all behavior is more complex and much less
certain.

The human brain is fantastically complex thing. Neurologists and psychologists
have done many experiments on it. The "replication crisis" is a good indicator
how difficult is to go from experiments on a few particulars to a general
understanding of how the brain works. I think the criticism of "functional
areas" that Luria made in The Working Brain should be read carefully.

The thing about this is: neurological research is great to add if what you're
looking for is " _what might be_ ", using methods that _possibly_ have
scientific and seem effective. But if you operate in terms of " _how things
absolutely are_ ", then one risks going into the realm of pseudo-science. And
there's a lot of supposedly neurologically based new age quackery out there -
much of it based things that "the latest findings" whenever said quack
happened to get their start.

~~~
Balgair
Thank you.

There is _some_ stuff in post that is somewhat useful, but the conviction of
the statements is a bit much. Nothing in the brain is simple, and most of
neuroscience is in it's infancy today. Dandy-Walker syndrome is an especially
extreme, but illustrative, case of how strange the brain can be on the inside,
yet present as normal on the outside[0].

[0]
[https://en.wikipedia.org/wiki/Dandy%E2%80%93Walker_syndrome](https://en.wikipedia.org/wiki/Dandy%E2%80%93Walker_syndrome)

~~~
solipsism
_In the majority of individuals with Dandy–Walker malformation, signs and
symptoms caused by abnormal brain development are present at birth or develop
within the first year of life_

Doesn't seem like "normal" presentation to me.

~~~
Balgair
[https://en.wikipedia.org/wiki/Hydrocephalus#Exceptional_case](https://en.wikipedia.org/wiki/Hydrocephalus#Exceptional_case)

"The person was a married father of two children, and worked as a civil
servant, leading an at least superficially normal life, despite having
enlarged ventricles with a decreased volume of brain tissue. "What I find
amazing to this day is how the brain can deal with something which you think
should not be compatible with life", commented Dr. Max Muenke, a pediatric
brain-defect specialist at the National Human Genome Research Institute. "If
something happens very slowly over quite some time, maybe over decades, the
different parts of the brain take up functions that would normally be done by
the part that is pushed to the side.""

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8ytecoder
“What is my body trying to tell me with that tight stomach, sunken heart,
clenched shoulders?”

I have been reading Radical Acceptance by Tara Brach and this is one of the
themes that keeps repeating in that book and in general in meditation. To
understand one's mind and the root cause of an emotion one need to focus the
attention on how one's body feels and what it's trying to say. While
meditation is now widely accepted as beneficial, I have generally been less
accepting or even dismissive of the surrounding teachings and method. I think
it's time to revisit my views and be more open to it.

~~~
radicaldreamer
I’ve had a similar experience. I think the reason is that there’s a lot of
noise in the field. A ton of low quality thought and half baked ideas or pure
nonsense.

But that really should not close one off to reputable sources like Tara Brach
(highly recommend people start with her guided sessions which are available
free on her site) who have a well of experience honed over the years.

One time in India, some family members took me to an astrologer. I was
extremely skeptical but this person was famous in town and well known
regionally as well. And when I voiced my concerns that the whole field was all
hocus pocus, one of my relatives said that may well be true for many
individual practitioners in the field, but if you think about it as a person
communicating to you using their own finely tuned heuristic for outcomes, it’s
a different story. Maybe the more reputable sources in these fields should be
thought of in that way, where you shouldn’t expect perfect accuracy but you
should use their thoughts and knowledge as a rough guide to a kind of
knowledge we have very few tools to directly explore rather than pure truths.

~~~
keepmesmall
Pure truths one of the most important tools in developing self-knowledge. IMO
going to an astrologer is akin to using a prostitute blindfolded.

You want to understand yourself, spirituality or even the universe? Study the
laws of nature, the 112 names of Shiva, the 72 names of God, 613 Mitzvot of
the Torah, the 4 worlds and 125 degrees of Kabbalah etc. etc. etc.

Heck, study the alphabet and how to write and pronounce it. Ladders abound.
Just pick one that seems like a challenge, and then pick a fun method of
studying it. I like to mix calligraphy and pronunciation practice in.

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marmaduke
I upvoted because I like to see popularizations of results from neuroscience,
but I would also caution against cherry picking papers and placing
interpretations atop them.

~~~
simmanian
> caution against cherry picking papers and placing interpretations atop them

I worry about this every time I read a "practical" article about the brain.
Can anyone tell if the main points in this article is generally accepted in
the scientific community?

~~~
ggggtez
I'd save yourself the trouble and throw it all in the garbage.

>Feeling heart-broken? Feeling angry and frustrated? Feeling sunken and
collapsed? Feeling energized and happy? All of these feelings will have had
their origin as sensations from vagus nerve.

This is a fundamental misunderstanding of everything to do with neurology.
There is simply no way to write a point by point rebuttal of how much is wrong
in this article.

~~~
marmaduke
Wow.. I had read through diagonally and missed this one, otherwise I would’ve
been a bit more negative.

The real shame is that reading about the different systems that do give rise
to these feelings is actually really interesting.

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mettamage
My simplified main takeaway from this post is: chronic stress seems to be at
least as bad as chronic alcoholism [1] and therefore we really _really_ need
to be masters at the art of relaxation.

The two forms of evidence that stood out to me: (1) the effect of an
overactive amygdala and (2) the negative effect of stress on the neocortex.

[1] Alcoholism isn’t mentioned in the post, that’s my own interpretation of
the potential damage it can go. I’m going to do an online search for it to see
whether that comparison has any merit.

~~~
ggggtez
I'd caution against taking anything in this article as truth. This is written
by a self help guru, not a neurologist.

~~~
mettamage
I know, fortunately I know enough neuroscience to know to what extent I should
believe this.

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saagarjha
> Feeling heart-broken? Feeling angry and frustrated? Feeling sunken and
> collapsed? Feeling energized and happy? All of these feelings will have had
> their origin as sensations from vagus nerve.

I thought emotions can from the limbic system?

~~~
eli_gottlieb
Emotions come from the entire body, as interpreted by the insular cortex
(internal sensation) and cingulate cortex (internal motor planning).

I'd have to check the source, but I'm pretty damn skeptical on _all_
interoceptive information flowing through the vagus nerve. I'm pretty sure my
adviser has told me that's Just Plain Wrong.

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TeMPOraL
I wonder how it is determined which neurons send signals "to" vs. "from"
brain. This 80/20 to/from split is surprising.

The reason I'm asking is because sending electrons up a wire isn't the only
way to signal with electricity. When the output that was high-impedance
suddenly opens up, allowing you to send electricity through, that actually can
be a signal _to_ you, that something on the other end has changed.

~~~
skohan
Neurons can be understood to be fairly directional. There is no direct
electrical connection between neurons: there's actually a small gap between
the upstream neuron and the downstream neuron. When the electrical signal
reaches this gap, the up-stream neuron releases a chemical signal, which is
processed by the down-stream.

So the state of the up-stream neuron depends very little on the down-stream
neuron: if the down-stream neuron is in it's refractory period and can't
process the chemical signal, the up-stream neuron can still fire all day, and
the chemicals it releases will essentially fall on deaf ears.

That is a somewhat simplified view, and there is such a thing as retrograde
signaling (chemical messaging from the post-synaptic neuron to the pre-
synaptic neuron), but it's believed these signals have less to do with the
primary flow of information in the brain, and probably relate to slower
processes like modifying the strength of the chemical signal in the affected
synapse.

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gloriousduke
"When your amygdala is active, you can’t have empathy for others"

This is an excellent example of those aspects of our existence that are
deterministic. No matter your willpower, you may be bound by biology to act a
certain way. Part of being a good person is to recognize these deterministic
effects and plan your life accordingly.

For example, if you get "hangry" often, keep a food item on hand at all times
so that you can address your hunger before you say something mean to your
partner et al.

~~~
agumonkey
bound may be too strict, plasticity allows for reshaping your emotions,
senses, how you process them

~~~
gloriousduke
I suppose that falls under "Part of being a good person is to recognize these
deterministic effects and plan your life accordingly."

The type of "reshaping" you're referring to would go beyond willpower in a
single moment. Probably something like cognitive behavioral therapy?

~~~
agumonkey
Yeah CBT is in that box and it's indeed not a oneshot effort more like a year-
scale (if not decade) process. The ideas aren't that complex, but like music
.. it's subtle and requires life experience.

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soared
> 2.) When your amygdala is active, you can’t have empathy for others

I'm curious is this is a mechanism behind social anxiety. In some social
situations I very clearly lose the ability to think - all thats left is an
empty mind and my body going through the motions. Its completely different
than my regular way of living (from my perspective, maybe not from other
people's perspective) but definitely makes it more difficult to connect with
others and build friendships.

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dahart
> When your amygdala is active, you can’t have empathy for others

Do being late for something and driving in traffic activate the amygdala? I
think I can feel that combination drain my empathy. I'm trying to actively
avoid those two things. Anecdotally, it sure seems to have a similar effect on
quite a few others too.

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happy-go-lucky
> I went to live in buddhist monasteries for a few years. There I was able to
> turn my focus away from outside of myself towards my own body, feelings and
> inner world.

That's from their Main Story.

I'm trying to tell myself that I can think effectively as long as I'm in
focus.

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pknight
Would have been better form to more substantially attribute Stephen Porges'
work here, only a small mention is placed under his chart.

~~~
LeonW
Great point, I feel incredibly indebted to Stephen Porges', both for my own
internal well-being and the lessons I've learned and can share with others.

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dschuetz
So, 2. + 5. + 6. might be the sources of bipolar disorders? Brain chemistry
out of balance means that activation patterns are being modulated differently
than before, and stress causes that in one way or another. Changed modulation
might trigger changing/cycling states of peace or alertness, shrinking or
widening associative activation. But why are some people more susceptible to
stress than others? What is different?

~~~
ggggtez
Bipolar is not related to stress disorders. Please don't try to use this
article as a primary source, because it misinterprets everything and tries to
put a "self-help" spin on it, which is just going to confuse you more.

~~~
dschuetz
Why are you patronizing? And what are "stress disorders"?

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sidcool
Haven't read it completely, but hoping it has something related to guts'
connection with brain

