Giant neuron found wrapped around entire mouse brain | Hacker News Reader

Giant neuron found wrapped around entire mouse brain

nature.com

83 pointsmcbits37 comments

This is very cool, and very hard! The observation has its own significance of course, but I think even the method they used is important in its own right.

Also shows how little we still understand of biological fine structure and detail. $deity is in the details!

Though, given my limited understanding of neuro, I still fail to see why having a single neuron that circumnavigates the brain should lead to consciousness.

  I still fail to see why having a single 
  neuron that circumnavigates the brain should 
  lead to consciousness.

Me too, but what an experiment it could lead to, and the questions it would answer.

Reasons it makes sense include the singular perception of self. No longer does that sense of being in one place, and perceiving one experience seem mysterious. If there's one container, and one self, the idea that the core of our living self ultimately resolves down to a single-celled animal depending on a collective of subordinate cellular tissues wraps up so many other details in an easily understood package.

Of course it raises the question of what mechanism drives such king-making? Is the sheer size of the neuron a factor? Is status determined as a zygote? Does status last from cradle to grave? If there's one master neuron at a time, does the master neuron's identity get exchanged or relayed to other neurons throughout life? How would hand-off work? What if there are conflicts? I'm sure there's no simple answer in any of these ideas, and the reality of such details will remain as complex as ever, if this is even the right track to follow...

But if it were true, maybe it opens the door to mastering one's entity of self, such that a person, or any similar organism might be capable of existing temporarily in a petri dish, lunching on agar, while the body goes in for a tune-up.

You're asking a great deal of a single neuron (or even a small set of brain-spanning neurons) if you expect it/them to be you. Functionally speaking, a neuron is a bag of sodium and potassium ions that fills and empties itself via various molecular valves, perturbing other little valve bags in the process. That billions of these can instantiate a human personality is fantastic enough in and of itself; the claim that personal identity can be reduced down to some particular little valve bag is utter nonsense.

But fun nonsense. Imagine if it really were so. Neurons die all the time, in the thousands every day. So one day that particular neuron dies, and you are gone. But nobody else can tell, because the other 100 billion neurons are still doing their thing. They now control an automaton without consciousness which, nevertheless, will emphatically claim to be conscious, should anybody ask. Because we all are, right? :)

Philosophical zombies are definitely interesting subjects for thought experiments.

For incorrect thought experiments. You cannot conceive p-zombie from first point of view, because there's no first point of view for p-zombie. If you conceive p-zombie from third point of view, you cannot be sure that it IS p-zombie, because you aren't God and p-zombie is identical to not-p-zombie from third point of view.

Well, the parents concept was that of a living consciousness becoming a p-zombie, which seems valid to me.

If there's no changes in behavior we usually associate with consciousness, then why we decided that those neurons were responsible for consciousness in the first place?

therein lies the problem - we can't detect consciousness from the outside.

The problem off course how we define consciousness, Koch wants it to be a few neurons that define it so his view of it would be different from someone using other methods.

Yes. It seems to me that they found the front side bus equivalent rather than the 'seat of consciousness'.

I imagine that there is more than one neuron and they just imaged one.

Presumably consciousness requires a model of the self, so a neuron that can sample from all parts of the brain would be well placed to build such a model. That's my theory at least.

>　I still fail to see why having a single neuron that circumnavigates the brain should lead to consciousness.

The number of neurons you can trace is limited by the methods: traditionally you can only stain a couple of neurons at most, otherwise the mangling axons and dendrites just make it impossible to differentiate between the neurons. Although now there are better methods (e.g. "brainbow" for barcoding neurons, "CLARITY" for whole-brain imaging).

In this case although it's just a couple sample neurons from claustrum, but given that same type of neurons in the brain tend to cluster together (which is how we differentiate brain regions anyway), it is likely that there are many, many more neurons like this in claustrum.

Claustrum has long been hypothesized to play a role in conciousness, however we know so little about this region (it was only a couple years ago people first recorded neural activity from that region!). This provides support about it because consciousness contains information about just all sensor/motor/cognition, therefore a neuron that computes consciousness should have access to a large amount of brain regions. So finding this neuron which basically connects the whole brain is supportive to this hypothesis. What's more supportive is the fact we have never seen neurons like this anywhere else: so even if it's just a couple of neurons in the claustrum, the potential bayes factor favouring their role in consciousness can be quite high.

While you are not incorrect in that consciousness stems, in part, from the interaction of various lobes/regions of the encephalon, consciousness as we perceive it subjectively (I realize this is a bit tenuous logically, but I am being both as accurate and precise as I can be) is a mixture of the world without and the world within our physical bodies.

I realize this is a little metaphysical, but the truth of consciousness is one that Penrose and many others refer to in a sense of entanglement, the sense that we are connected beings and that connection drives consciousness inasmuch as what we perceive, how we perceive it, and the reactions to that perception are all part of what Feynman describes extraordinarily well in his work regarding Q.E.D.

That is to say, and I'll try to use the most layman-esque terms I can while maintaining scientific integrity: what you know, what you perceive with your mind, is known because of how it is and how you are. The mental connection between those two things is very real. Here's a nice little "thought" experiment for you.

Take a walk somewhere. If you can, note what you are thinking in relationship to your memory of the things that you are observing (with all of your senses) in terms of their metaphorical juxtaposition and/or relationship. That metacognition is a good example of the entanglement that comprises our consciousness.

Therefore, the Claustrum (and I love that name, Santa Claus-esque, very apropos) is merely (ha) the network hub if the senses, but it does not direct consciousness. The interaction of the senses, the external (autonomous as it is and therefore unregulated by the Claustrum) world, and all of your memories, imagination, theorizing, etc, are what comprise your consciousness. Inordinately complex, yes, but nonetheless a definite phenomena that we can seek further to define, understand, and recognize as something we can model and learn more from as we meander our way to enlightenment.

If this seems a bit dense, or a bit abstract, it's because the knowledge is incredibly knew and has less grounding than even something as nascent as Dark Matter, Quantum Computing, or whether global temperatures are steadily on the rise.......

You can look at it like this: you carry around in your brain a computational model of the world, and the model includes yourself, because you are part of the world. The apparatus for receiving and making sense of input from our external senses, and input from the rest of the brain itself, is the same.

Consciousness is the brain perceiving and modeling itself. If that sounds totally recursive, it's not, because there is much more to the brain than consciousness.

For example consider recent research showing that emotions are essential to making decisions. We don't consciously choose which emotions to experience. But take away emotions, and people find it very difficult to make decisions. They can evaluate the options, but can't choose which one to take action towards.

Our conscious minds spend most of their time reacting. After all most people don't think to themselves "I consciously choose to like chocolate ice cream better than vanilla." But they might think "I consciously choose to not eat ice cream tonight."

The bayes factor favoring their role as part of nonspecific overall brain activity regulation is high too.

From the image it looks like they're visualizing dendrites rather than a big ass bifurcating axon. That neuron is really huge if true.

I don't follow the jump from well-connected neuron to consciousness at all. Why does consciousness have to be based in the physical brain? That doesn't even begin to explain collective consciousness, or the fact that observation/awareness affects observed objects.

Observation (as used in quantum mechanics) has nothing to do with consciousness. Consciousness is not a prerequisite to measure an observable.... That's a total non sequitur...

We're just going to have to agree to disagree on that one. The effects of observation is all about consciousness, and has nothing to do with measuring.

You are incorrect.

Very constructive, now you can go back to observing and measuring unconsciously :)

Well obviously you never dealt with automation in the lab. You don't have to have consciousness to observe or measure but you damn need it to draw meaningful conclusions.

If you want constructive responses you need to make non idiotic comments.

Humans can't observe without a conscious because humans have a conscious. That is related to the nature of being human and has nothing to do with any thing fundamental to observation.

http://www.bbc.com/earth/story/20170215-the-strange-link-bet...

I'm far from the only one who disagrees with you. And I'll just note that calling people idiots is the opposite of constructive.

If it's not physical, it's probably not observable, and science deals with things that can actually be observed. If it is not physical but observable... by what means does it affect actual matter? Neurons have to be coaxed to fire somehow, and if there's a nonphysical spirit poking them then that breaks physics.

Resorting to a nonphysical explanation doesn't explain anything or help you predict anything, so scientists aren't interested. Once they've have ruled out all possible physical explanations then maybe they can give up on them, but it's a long way to go.

Reply on news.ycombinator.com