How the brain increases blood flow on demand | Hacker News Reader

How the brain increases blood flow on demand

hms.harvard.edu

163 pointsgmays84 comments

Recently I started taking an angiotensin II receptor blocker as a medication to lower my blood pressure. The first week was difficult because my body couldn't significantly raise blood pressure during periods of sustained effort, like exercise and yardwork. I believe I'm over this now. Fortunately, the medication seems to be effective and I haven't experienced any negative side effects yet. Some people who take this medication have reported bad side effects, including "brain fog" while using it. I wonder if/how this medication might interact with the blood pressure control mechanisms observed in this research.

I also take an angiotensin II receptor blocker and my experience has been similar. Additionally, I experience a perceived effect on stress levels as my pulse and blood pressure do not rise in stressful situations.

On the negative side, I definitely have a harder time reaching my maximum pulse when working out.

BP meds are dumb. Lose weight

You assume that everyone has enough fat to shed to arrive at a desirable blood pressure. This is not the case.

Worse, once you start it is very very hard to leave them

Always fascinating to me how we are brains, trying to understand how we work. Cool research!

why did it name itself brain or whatever linguistic origin that brain is ultimately derived from. perhaps it was Brian and some brain out there made a typo and here we are today

He's not the seat of consciousness — he's a very naughty boy!

"I used to think that the brain was the most wonderful organ in my body. Then I realized who was telling me this." - Emo Philips

Along this same line of thought, I've always found it particularly fascinating that the universe is exploring the universe through molecules arranged into humans. Is the Universe the conscious one here?

What I never got is, why do we experience anything? Why can't the universe exist as a simulation where people do people things without having to consciously experience it all? Why can't I just shut off my experience and let my body do whatever it would do without having to put in effort, the same way everyone else's body does whatever it'll do without me having to experience everything they do?

There might be one like that out there but no one will know about it.

Friend, let me introduce you to the topics of philosophy, theology, and cosmology!

David Chalmers coined the phrase "the hard problem" of consciousness.

https://en.wikipedia.org/wiki/Hard_problem_of_consciousness

The two big problems: 1) Why is anything? and 2) Why am I here and you're over there?

The Hindu School of Philosophy named Samkhya/Sankhya gives you the appropriate Worldview in which your questions are answered - https://en.wikipedia.org/wiki/Samkhya

There is an "Objective Reality" (mutable, evolves into many forms and includes both material/non-material concepts) and a "Witness-Consciousness" (immutable and attributeless). The latter is embodied in one form of the former which we call Sentient Living Beings. But we forget the distinction between the two and experience reality through its own subjective evolutes within the embodied being i.e. Sensory Mind, Intelligence and Ego. Various techniques/practices have been prescribed in Samkhya/Yoga/etc. to break out of this illusion and realize that one is simply pure awareness/consciousness beyond any experience. This is what is called as Kaivalya/Moksa/Nirvana i.e. a state of mind in which there is total freedom from everything to do with objective reality.

See also the paper A landscape of consciousness: Toward a taxonomy of explanations and implications and previous discussion on it here - https://news.ycombinator.com/item?id=40844824

I have been reading the yoga sutras recently and it strikes me how applicable it is. The weird stuff about attaining magical powers is... cool, but samyama and the nature of the reflective consciousness have a lot of explanatory power imo.

Samkhya gives you the Worldview/Model and Patanjala Ashtanga Yoga gives you a practical framework/discipline to implement it. Here is a older comment of mine which you might find useful - https://news.ycombinator.com/item?id=41538322

Also see the classic Yoga and Western Psychology: A Comparison by Geraldine Coster - https://archive.org/details/in.ernet.dli.2015.189086/page/n1...

> why do we experience anything?

Because the Essence that is the arrangement of molecules replicates onto other molecules, and it is more effective at replicating when it dedicates some of it's molecules to perceive and model it's own existence, in order to run experiments on it. That way it's more likely to find a behavior for the rest of the molecules to successfully replicate. So the molecules experience themselves, and the experience becomes more intense the more advanced the experiments are that can be run on the model.

What is the Essence? In my head I picture movement or electrical fields propagating from some sort of proto cell like structure, but the more I try to “zoom” in, the more I try to find the finger that caused the ripple on the pond surface, so to speak

Just the arrangement, the structure, of the simpler things a system is made of, which allows a system to a) sustain and b) replicate.

My adopted working hypothesis is that we have to simulate what others observe/think in order to predict their behaviour and then adjust our own expectations and plans. It's a lo-fi model, because we don't have access to their internal workings - and yet it's a powerful model because it needs to predict the behaviour of very complex agents. If we then turn that powerful machinery onto ourselves, we can add all the extra information we didn't have of others. So it's a much richer, more detailed description of what's going on.

It's not true that we have to be conscious - we can do things on autopilot too. The same way we can be thoughtless in treating others - we can turn the machinery off.

This autopilot works very well with a car and a very well known road ( like a daily commute).

Recently I was thinking of a very hard problem and I cannot absolutelly recollect approx 30 minutes of the drive home. Apparently my body and some part of the brain took over the driving, while my cortex was busy with the problem reserving the short term memory completly. I snapped out of the situation when apparently a stronger break was needed, and this intrerupted my flow and popped my attention to the road. Fascinating!

> Apparently my body and some part of the brain took over the driving

That part of the brain is the cerebellum (mostly).

> Why can't I just shut off my experience and let my body do whatever it would do without having to put in effort

I do feel like most forms of leisure - watching / playing something, alcohol / drugs, sleeping - are basically this, you lose some of your consciousness and awareness in favor of what you're focusing on, or floating / free associating.

Isn't that what death is? No experience whatsoever. Unless the universe ends up being a closed system and we have this discussion or slight variations infinitely many times.

How would your body react to stimuli without experiencing it?

Doctors use a hammer on the knee. Instinct and reflex is powerful, that’s why it exists down to amoebas and single celled organisms. A body that doesn’t have autonomic reactions isn’t going to reproduce as capably.

If you want to explore the future possibilities of that line of thought, then Greg Egan's Diaspora is good read.

The Minds That Left Reality | Diaspora

https://youtu.be/yYwqy4bzHG4

Such an incredible book! I read it like 8 years ago and think about it often enough that it was on my mind just yesterday :)

I adopt the theory that all consciousness is energy vibrating the strings of the quarks that make up the atoms of the universe that make up humans that study the workings of the universe and thus, ourselves.

A chorus of being.

Are you thus postulating that the rock next to me is as conscious as I am?

That's a weird use of the term. Doesn't match how I would define it, but you do you.

Panpsychism.

https://en.wikipedia.org/wiki/Panpsychism

I think it's a bit kooky, but there are weirder things that are true in this little Universe.

Yes but due to its density, it takes millions of years to form a sentence. If you listen closely to trees, they also speak with one another. Mountains do too. We just have the attention span of a gnat.

I’m sure at some cosmic level there’s cities of marbles like ours just humming away.

Perhaps humans are not the end goal of the arrangement process. We like to think we are, but we're likely just a phase.

How come you are assuming that there is an "end goal"?

Humans believing that they are special is as old as human history goes. Special as a species, but many groups also consider themselves special, and individuals as well. Seems to be an emergent thing from the human psyche. One that has had terrible consquences over the millenia, but I might be overlooking the upsides.

I think you are right. The "I am special" is rampant in today's society as well, and it causes a lot of harm, along with group thinking or mentality, us versus them, and so on.

I am special. My friends say "he's a bit special."

I am special, too, according to many people. Special in the sense of being on the spectrum. :)

Humanity is special. All evidence points to us being the only technological species in the universe. Way too many holes in the theories that aliens are simply hiding. If we aren’t in a zoo, we’re probably alone, and that in and of itself makes us special.

But I should mention this PoV only works from an “all humans are equal” angle.

Yeah, I was referring to people who think they are special and others are not.

Because the process of "arranging" requires an end goal, according to the definition of the word. No assumptions needed.

I was replying to the person who suggested the universe might be consciously exploring itself (goal) via an arrangement of molecules into humans. For fun, maybe the arranging process is at the beginning and the end goal is some kind of cosmic party after which everything resets again, or something.

Are we though? If you look closely at it, there is no evidence that brain causes consciousness, just correlation.

There's a massive amount of evidence that consciousness occurs in the brain. If one were to propose that it's just a correlation then some kind of convincing argument would need to be made about how and why.

True, and there is also plenty of evidence which snows how neuronal degradation in some pathways leads to losing aspects of consciousness.

I read GP comment as "there is no evidence that everything having a brain is conscious (and vice versa)", not as "the place where the individual's consciousness operates is the brain".

The former could be applied to whatever LLM is the hype of the day.

It's interesting though that the only consciousness that I'm sure of exists is my own. Anybody else's is just somehing I'm assuming. You can measure intelligence, but not consciousness.

I believe there is thorough, observable, evidence to suggest that consciousness is manifest exclusively through the brain.

Persons with damaged brains have damaged consciousness. Persons with underdeveloped brains have underdeveloped consciousness. People without functioning brains have no detectable consciousness.

There is a metric ton of observed and collected data on consciousness.

Of course evidence does not equal proof…

I appreciate your point, but be sure to take a look at the current state of the mind-body problem to understand that those evidences you brought up point to the brain as mediator of consciousness, not the cause.

They absolutely point to the brain as the cause. To suggest otherwise is to introduce unscientific/superstitious concepts like souls or whatnot, which violates Occam’s razor. If that’s the road you want to go down, come back when you have independent evidence for that.

> Today a young man on acid realized that all matter is merely energy condensed to a slow vibration, that we are all one consciousness experiencing itself subjectively, there is no such thing as death, life is only a dream, and we are the imagination of ourselves. Heres Tom with the Weather.

-Bill Hicks Don't take this as downplaying at all, because it's a fantastic and uplifting revelation, so long as one doesn't presume they're the first to consider it (it is even better this way imo)

A physicist is just atoms studying other atoms.

So you can get brain hard?

You can get nose hard too! https://wikipedia.org/wiki/Honeymoon_rhinitis

Brain blood perfusion is quite amazing.

I don't understand from their research if

1) The the blood flow is following the computational/metabolic demand (via the endothelial cells communicating via gap junctions)

2) the brain is signaling the endothelial cells directly.

Maybe the paper explains it, or maybe more research required.

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