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> also anyone know how is lymph pumped? I don't think the heart pump lymph so is it stagnant?

I have a close friend who is working on getting certified as a massage therapist. Skeletal, muscular, and vascular anatomy make up a big part of the required knowledge for the certification.

Two interesting things I learned from them:

1. The lymphatic system is massive and runs alongside our vascular system. For example, there are many lymphatic veins that run through the head and face that empty out just near our clavicle, where they’re the picked up by large vascular veins to the heart, and then on to the liver for filtration.

2. The lymph system is not attached to our heat, and movement of fluid in those veins is purely driven by mechanical motion of our bodies. This is often why paraplegics or folks with other forms of paralysis end up with swollen feet—lymphatic fluid gets trapped in the extremities and collects whoever gravity dictates.

Fascinating stuff. Gave me a much greater appreciation for the level of knowledge and skill to be a massage therapist.

Wow I wonder how much power does gravity has over lymph repartition in the body? I mean wether I lay down or stand still probably impact the "coverage" of our body by the immune system. There might be correlates between time to recovery and human position and movements then.

BTW bugs do not have vascularisation their body is one single flask of stagnant fluid. And their brain is distributed..

Fun fact: one of the red flag symptoms of a headache or migraine is if it is significantly less severe sitting up vs lying down. Or if it gets worse when you sneeze. I am NOT a doctor, but IIRC this can be a signal of serious issues they could be causing such a headache, as it means the blood pressure caused by lying down or sneezing is potentially stressing vascular structure in your head.

See: https://youtu.be/d2vW_CHWqo4

A thing I find interesting is that autopsies are finding that folks with tattoos end up with stained lymph nodes as the tattoo ink gets spread through the lymphatic system.

As tattoos have become hugely popular in the last couple decades I wonder if we’ll start seeing more health problems associated with the chemicals used in inks.

Ink is known to be found in the blood for a bit of time after the tattoo (people can’t even donate for a year after where I live?).

So it is not that surprising to find it in lymph nodes whose very purpose is to accumulate foreign things in the body and possibly make them “meet” with immune cells. Also, tattoos are not completely static structures, they are tiny ink droplets that do get collected by our body — we are just unable to handle a certain size of them. Tatto removal works exactly by breaking up the ink to smaller pieces which our cells can handle.

It used to be 12 months in the UK for giving blood after getting a tattoo too, but they changed it fairly recently to be after 4 months.

Do they talk about enforcing good cardiovascular health and PE as a way to maintain lymphathic drain too ?

No idea, but from what I’ve head it’s commonly understood that people who regularly move and exercise will generally have better lymph circulation for that reason.

Yeah it makes sense but it's folk level logic so I was curious if it was mentioned in classes too.

Personally, even wounds heal faster now that I took biking again. Digestion too.. we're really made to move on a regular basis.

Fun fact: the brain also has a lymphatic system, which wasn't described until about ten years ago. It's called the glymphatic system, and apparently it was rather difficult to spot.

I have a vested interest in very precise understanding of brain structures (qualia too but less pressing matter).

In particular:

- visual perception of self - visual perception of others

and the somatosensory aspect of those points, how do i represent your emotions and body in my head, my own body / image / emotions too; and how do they relate.

if that means anything to anybody, comment down.

Thanks in advance

The brain's lymphatic system was confirmed to exist only recently, in 2017.

https://www.theatlantic.com/health/archive/2017/10/scientist...

https://www.sciencedaily.com/releases/2019/07/190724133649.h...

this is a terrible list of 'brain facts'. they're not interesting or constructive to a larger understanding, and analogizing the cerebellum to a GPU is naive and misleading to the point of being insulting. working neuroscientist don't think about consciousness, we look at neurobiology, develop experimental techniques to allow imaging of ever larger numbers of neurons, try to understand how the brain computes.

I don't see how one could boil down the staggering complexity of the field in the one-bite popsci factoids that leave a layperson with any useful model of the brain. People certainly try though (ahem, Andrew Huberman...).

Here are some facts though: you have some neurons, they do things sometimes. we have some vague ideas about what different bits of brain do in very specific context. we have absolutely no idea how it all fits together, and are decades away from such an understanding. the fruit fly visual cortex, which is several orders of magnitude smaller than mammalian cortex, has been exhaustively studied for 40+ years, and we are only recently starting to build a circuit level model of the computation in the first layers. Here is your fact: brains are the most complex objects in the known universe

What an absurd dismissal. > they're not interesting

You have a failure of appreciation, yet those facts are potent and surprising.

>constructive to a larger understanding

Yes they are not, who cares? Teaching neuroscience is of course a non-goal of my comment, what an irrelevant thing to say..

>analogizing the cerebellum to a GPU is naive and misleading to the point of being insulting.

Exactly, but if you had allocated a few neurons while reading my comment you would have seen I said "a poor simplist-ification" akin to only transmitting the idea that it is the place in the brain with the most compute power/parallelism.

>working neuroscientist don't think about consciousness, we look at neurobiology,

Such a useless thing to say. It is a truism that scientists mostly focus on what can be studied by the means of metrology/empiricism and indeed for now, qualias are low-studiable. Saying this has no more value than saying water is wet.

Your shallow dismissal is just a pretext to your layman explanation of what is the brain. Explanation with btw zero level of detail. I have read over 1000 papers in neuropharmacology and there are in facts a lot of things we understand about brains. But, the C.elegans ~150-300 neurons, which is much simpler than the fruit flies, is as of now unexplained in terms of neural code, despite having an almost complete connectome of its neuroreceptors. But no the C.elgans is not one of the most complex thing in the universe. This is a fallacy that make seems progress seems impossible. The truth is, C.elgans has a relatively reasonable complexity, however we lack real-time datasets and we lack accurate instruments to observe and retroengineer the while system.

> we lack real-time datasets and we lack accurate instruments to observe and retroengineer the while system.

wrong again. whole brain 2p imaging is routinely performed in c elegans ( and drosophila for that matter) for a number of years now. in fact whole brain ephys in c elegans is feasible, although it would be an experimental tour de force. c elegans does not have '~150-300 neurons', it has precisely 302, and the complexity therein cannot be underestimated. it wasn't a layman explanation for I am not a layman, and you are missing my point, which is that reductive facts about such staggeringly complex things are neither interesting or useful. it's the feynman magnet explanation, but grumpier

Come on, who do you think you are talking with? I have read many papers about C.elegans and my claims are backed up: "the inability to reliably identify all neurons within whole-brain recordings has precluded a full picture with circuit-level details."

"we expect our work to aid in these endeavors (Bargmann and Marder, 2013; Brennan and Proekt, 2019; Kaplan et al., 2020; Kato et al., 2015). A richer set of network responses, even for simple chemosensory inputs, has broad relevance in understanding sensorimotor processing"

"The application of NeuroPAL to whole-nervous-system activity recording is mainly limited by nuclear localization of the GCaMP activity sensor, as this may fail to capture highly localized events in axodendritic compartments. This limitation, combined with potentially incomplete or variable anatomical synaptic annotations, may have contributed to the lack of correlation we observed between functional activity and synaptic connectivity."

Neuropal is an extremely recent advance (2021) https://www.cell.com/cell/fulltext/S0092-8674(20)31682-2?_re... it is the first to allow a complete mapping of GABA receptors (except mitochondria GABA translocator) however complete maps for other receptors, such as mGLURs, NMDA, kainate, ampa, etc are LACKING, as I said. Let alone realtime data that take into account the individual variances over multiple worms. (they should study genetic clones btw) real time data are rare, nowhere near big-data https://www.youtube.com/watch?app=desktop&v=B4gNamS8Ars and when they exist, they lack the complete information (receptor locations, precise neurostransmitter density per axon, etc) C.elegans might be trivial to understand, without a complete map of axons and recpetors, it would still appear generally un-studiable.

As for the 150-300 neurons it is a matter of debate. IIRC the paper I linked refer to ~150 neurons in the head, the rest would be the PNS, not the CNS. But I'm not sure of the exact CNS/PNS ratio besides this paper.

i really couldn't care less how many papers you've read. whole brain calcium imaging is routine, no one expects it to be the whole picture. it's useful though.

and no it is not a matter of debate, there are precisely 302 neurons

it's useful and yet understanding how brain works precisely require better instruments and datasets hence the understanding of the brain is not bottlenecked on infinite complexity but before anything, on good old metrology. Q.E.D

oh yeah well done completely avoiding the PNS question, so according to you neurons in the tail are relevant to worm cognition? spoiler except for tail local stimulus (e.g. tactile, heat) I doubt it

QED is something you write after proofs not incomprehensible sentences. there is a compelling argument to be made that what neuroscience is missing is theory, not data. there is quite a lot of data.

i am dissappointed, although not surprised that someone who relies on appeals to authority when arguing a point is of the mindset that in an organism so finely optimized that it uses biomechanical feedback in gait generation where larger organisms use central pattern generations involving larger number of neurons that some neurons are more important than others. neurons are expensive.

guess you had better read some more papers.

I will plainly repeat my citation from the previous c.elegans paper ""the inability to reliably identify all neurons within whole-brain recordings has precluded a full picture with circuit-level details."" and the lack of glutamate receptors mapping.

Those are sufficent to asses we are bottlenecked on data. We lack theories especially because we lack data. Yes of course we have a lot of data, which is useless without a complete picture. try debbugging a complex software with only partial, limited logging, the task become easily intractable. But it seems you are more interested in a clash than in sharing knowledge. My argumentation is sound and valid, which make it cogent, authority is unecessary to come to an agreement.

*Puts mr bucket of water back where they came from*

FWIW that's not how you argue, that's just letting all the air out of the balloon.

As for your arguments, IMHO humans are fundamentally wanderers, and we stumble on discoveries and accidental solutions to problems as much (if not more often) than we intentionally set out to understand or achieve something. Given the expanse of the brain, the theoretical paradox of a scanner trying to scan itself, and the post-discovery nature of how we structure and organize things, I think we'll only make progress once we fully let go a bit.

Not to a stupid extreme, of course - unhinged conspiracy theories are as useless as trying to build load-bearing insights from drug experiences, IMHO - but just scientifically accepting that we'll never truly understand how we tick until we accept the wild nature behind it. We are not nearly there yet.

I liked the GP comment.

Here's an interesting fact about the cerebellum: it has more neurons than the rest of the brain combined, and as far as we know, all it does is help with balance a bit. There have been cases studies of people with a fully ablated cerebellum, and they can still walk, just a bit unsteadily.

> There have been cases studies of people with a fully ablated cerebellum, and they can still walk, just a bit unsteadily. ? I had heard the cerebellum is responsible for predicting the next token in a sentence (reminiscent of language models) but you're saying language is not impaired without a cerebellum?

The axons are just as important as the neurons. While neural networks are not good analogues of the real thing, one can imagine that no matter the neurons, without weights between them it would be utterly useless. The cerebrum is chock full of axons.

> The axons are just as important as the neurons

We don't know about that.

> without weights between them it We don't know where are located the weights but yes probably. We know for sure that individual neurons and axons do not reduce to a single floating point though. They have action potential memory and many dynamic modulators. Basically I believe the idea that neurons are mostly doing linear regression (which is what neural networks are) is very broken. I have read papers about neural coding and neurons are able to encode information in the spike timing frequency and in the strength (weight) but non of those two mechanisms even begin to explain how the system works.

Anyway to answer your comment you have a tentative point but mostly unknown. It is unknown how much percent of human axons are in the cerebrum vs the cerebellum. I would be surprised if the cerebellum would have less since I expect some kind of neuron/axon proportionality. Especially since the main neuron type in the cerebellum are highly branchial.

> The axons are just as important as the neurons.

what. an axon is a component of a neuron

are you referring to glia?

No, I meant to highlight that “most neurons are here” may not be the important question to ask, but their interconnectedness which is achieved through axons, and which gives the most volume of the brainz

indeed the focus of most research is the neuropils

It would be kinda funny if it turns out our brains are all running LISP underneath. duck

Always has been. BTW homoiconicity matters in artificial intelligence research https://en.wikipedia.org/wiki/Homoiconicity

> your neurons are not in your "brain" 90% of your neurons are not in what you generally denote by brain. They are in your cerebellum.

Excuse the dumb question, but what's in the brain then? Or are you meaning to say that the cerebellum has a much higher density of neurons than the brain?

Well clearly it means the "brain" (the cerebrum) contains less than the remaining 10% neurons https://www.cancer.gov/publications/dictionaries/cancer-term... Shared with the midbrain and spinal cord. Of course I am excluding PNS neurons

I don't know where you get the idea brain does not include cerebellum. This is completely false

Re-read my sentence, yes the cerebellum is part of the CNS and so is the spinal cord. Is the spinal cord part of the brain? Why not. What I meant is what people generally denote and imagine when we speak about the brain, is actually the cerebrum https://www.cancer.gov/publications/dictionaries/cancer-term... The cerebellum, pons, etc are distinct extensions.

The brain/spinal coord is commonly divided at the start of the brain stem. By all accounts, the cerebellum is part of the brain.

It is part of the brain but not in the mind of the layman which is what I meant. If you asked to someone wether the vast majority of our neurons are located in the cerebrum (not the cerebellum) they would say "of course".