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| ▲ | vercaemert 2 days ago | parent | next [-] | | I worked on the Human Connectome Project. If they freeze the vesicles that deliver transmitters and make them analyzable, you've got all the information you need. In terms of a modern ANN, it's the connections (axons) and the weights (transmitters/receptors in tandem). That said, this article doesn't get to the point in the free section. How are they collecting the information? Slicing is inherently destructive. Someone's got to manufacture an entirely novel imaging modality. Perhaps they could scan millimeters ahead of the slice at a resolution high enough to image receptors. Not possible currently. | | |
| ▲ | roarcher 2 days ago | parent | next [-] | | > If they freeze the vesicles that deliver transmitters and make them analyzable, you've got all the information you need. How can we possibly know that the non-connectome details of the brain don't influence computation or conscious experience? It seems we ignore these only because they don't fit neatly into our piles of linear algebra that we call ANNs. | | |
| ▲ | vercaemert 2 days ago | parent [-] | | Take a gander at the OpenWorm project. It's a great example of how simple neuronal activity is (given details like the connections, number of receptors, and transmitter infrastructure). SOTA models of neuronal activity are simple enough for problem sets in undergraduate biomedical engineering programs. Sure, to your point, we don't know. But the worm above (nematode) swims and seeks food when dropped into a physics engine. My main point is that the scale of the human brain is well beyond the capabilities of modern imaging modalities, and it will likely remain so indefinitely. Fascicles we can image, individual axons we cannot. I guess, theoretically, we'll eventually be able to (but it's not relevant to us or any of our remote descendants). | | |
| ▲ | roarcher a day ago | parent | next [-] | | > But the worm above (nematode) swims and seeks food when dropped into a physics engine. Nematode worms have an oxytocin analogue called nematocin that is known to influence learning and social behaviors like mating. As far as I can find, the project doesn't account for this, or only minimally, but aims to in the future. It's not surprising that immediate short-term behaviors like movement depend mostly on the faster signaling of the connectome. But since we know of other mechanisms that most definitely influence the connectome's behavior, and we know we don't account for those at the moment, it is not accurate to say that the connectome is "all the information you need". I agree that mapping the connectome of the human brain is impractical to the point of impossibility. But even if we could, the resulting "circuit diagram" would not capture all the details needed to fully replicate human cognition. Aspects of it, sure. Maybe even enough to make it do useful tasks for EvilCorp LLC while being prodded with virtual sticks and carrots. But it would be incomplete. | |
| ▲ | DoctorOetker a day ago | parent | prev | next [-] | | Why would axons be unimageable? There's research on the translation process where cells are basically flash-frozen (to avoid water crystals), then imaged with cryoelectronmicroscopy / AFM etc. where they image the translation process (RNA to protein) in order to get snapshots and get a better understanding of how the folding proceeds and is aided. If we can image sub-cellular features, what makes you believe we can't trace all the axons, dendrites and the synapses? It seems more like a question of how to do it cost effectively at scale, not so much a question of "can we or not?". | |
| ▲ | bitwize 2 days ago | parent | prev [-] | | I saw a putative 3D animation of a fly whose brain had been digitized and then run in a simulation. It buzzed around, sipped food it had found on the ground, even rubbed its forelegs together as flies do. A true Dixie Flyline. We live in strange times... |
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| ▲ | cjbgkagh 2 days ago | parent | prev | next [-] | | > If they freeze the vesicles that deliver transmitters and make them analyzable, you've got all the information you need. In terms of a modern ANN, it's the connections (axons) and the weights (transmitters/receptors in tandem). This is exactly what I’m doubting, how can you be so sure? | | |
| ▲ | vercaemert 2 days ago | parent [-] | | Same question answered under other comment. | | |
| ▲ | cjbgkagh a day ago | parent [-] | | Yeah but it wasn’t though. I found your answer unconvincing. I suppose “we don’t know” is an answer but that is nothing like “we have all the information we need” |
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| ▲ | caditinpiscinam a day ago | parent | prev | next [-] | | Am I right in thinking that even if you had all of the connections and weights mapped out for a brain, the specifics of synaptic plasticity are still pretty poorly understood? | |
| ▲ | smj-edison a day ago | parent | prev | next [-] | | What is the state of the art in regards to how neurons learn over time? Do existing neuron models account for that? Being trapped, unable to learn anything, sounds terrible. | |
| ▲ | kingkawn a day ago | parent | prev [-] | | All the information to replicate the structure we have delineated. But what else? |
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| ▲ | adrianN 2 days ago | parent | prev [-] | | It is my understanding that for the animals where we have a simulation of the full connectome the behavior you see approximates the real behavior reasonably well, so maybe the jury is still out as to whether it is sufficient or not. |
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