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[This is the second version of another question: How does consciousness depend on spatiality?]


I admit that the technical details of the following thought experiment sound completely weird but that's what it has in common with many other brain-related thought experiments:

Consider a brain in a vat and that its conscious experiences are determined by the firing patterns of its neurons.

Consider a super-tiny nano-device placed into the gap of a synapse: it absorbes all neurotransmitters emitted from the pre-synaptic neuron and re-emits them after a given period of time such that the post-synaptic neuron just receives and reacts on them with some delay.

Now consider these devices placed into all synapses of the brain in the vat.

If one assumes that the conscious experience of the brain is essentially the same as before, just (indetectably) slowed down, then it makes sense to go one step further. (If not so, one can stop here.)

Replace each nano-device by two devices (an input and an output device) which communicate by a super-thin optical fiber.

Now move all neurons to arbitrary positions such that the lengths of all optical fibers are the same, so the constant speed of light guarantees that the delay at all synapses is the same.

What would the conscious experience of the distorted brain in the vat be, assuming that the neurons exhibit exactly the same firing patterns as before, just (indetectably) slowed down and at different places?

Note that an important assumption has been made: that the communication between neurons is completely governed by neurotransmitters at synapses. Electrical synapses and neuromodulators (which are transmitted differently) are ignored.

Edit: Another caveat is the fact, that changes of synaptic strengths (i.e. learning) that rely on the simultaneous firing of spatially nearby neurons could not take place. So the isomorphism of neural activities (and thus conscious experiences) would break down rather fast, and thus the thought experiment may make sense only for some seconds or minutes (as long as synaptic activies don't deviate too much).

  • Interesting. I think this thought experiment does not theoretically breach any scientific principles that we know now (of course, with current technology, there’s a huge technical obstacle to set up such an experiment). So, the answer to this thought experiment should be physically valid (verifiable to be true or not when the necessary technology comes) and useful for future theoretical development on this matter. But it’s not an easy question, and I’m busy today and can’t formulate the answer right now. So, just want notify you that I’ve seen your question. – user287279 Jan 17 at 0:45
  • To the down-voter and close-voter: What's wrong with the question? (It's by no means obvious to me. Maybe it's considered a "What if ______ happened?" question - as discouraged in the help center - but there are other questions with the thought experiment tag that are quite well perceived. So why do you find it off-topic, please?) – Hans-Peter Stricker Jan 18 at 15:01
  • "changes of synaptic strengths (i.e. learning) that rely on the simultaneous firing of spatially nearby neurons could not take place" Why not? The changes in strengths are just due to the particular neurotransmitters that flow across the synapse between two neurons when they fire at close to the same time, there's no reason you couldn't have an artificial system that would make sure the same neurotransmitter flows happen for neurons that were originally adjacent before they were artificially separated. Neurons don't have some kind of sense that would tell them the neuron is "really" far away. – Hypnosifl Jan 25 at 16:57
  • @Hypnosifil: I thought of the electromagnetic field surrounding each neuron that could be "sensed" by other neurons? – Hans-Peter Stricker Jan 25 at 17:02
  • A more relevant concept here would be "retrograde signaling" (see Wikipedia on Long-term potentiation") – Hans-Peter Stricker Jan 26 at 9:11
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I haven’t found any literature that discusses matter similar to your thought experiment, so the followings will be just my interpretation of some existing theories as I understand them.

First, let’s be clear what it means for something to be the same when it has been altered (like being distorted in your thought experiment). IMO, that thing will functionally remain the same if its functional relation to other things remains the same. To be more specific, its cause-effect relationships with other things have to remain the same.

Now, as far as I understand, according to current understanding of neural signaling, when neural circuit A sends information I1 via its signaling pattern S1 to neural circuit B, neural circuit B, after reading and processing the information, will have signals circulating in its circuit in some particular pattern – let’s call this P1 (which is the newly processed information in neural circuit B). So, I1 and S1 will result in P1. Similarly, I2 and S2 will result in some pattern P2, and I3 and S3 will result in P3, and so on.

Next, suppose neural circuit A is altered in the way described in your thought experiment. If the firing patterns and all other synaptic transmission characteristics at all synapses that neural circuit A makes with other neural circuits remain the same (let’s call this Condition C), then the signal-transmission effects at all synapses should remain the same and I1 and S1 should still result in P1, and similarly for I2/S2, I3/S3, and all other information that neural process A sends to other neural circuits. Thus, so long as its signal-transmission effects on other neural circuits remain the same (Condition C is fulfilled), no matter how you alter neural circuit A, all its information that it sends to other neural circuits will has the same effects (or means the same) to other neural circuits as before. So, if conscious experiences is determined by the firing patterns as you hypothesized, the conscious experience of the so-distorted brain, like other information that is transmitted by signaling patterns at synapses, should remain the same as well (if Condition C is satisfied).

Do existing theories about consciousness give this prediction?

According to Chalmers [1.2] in his principle of organizational invariance: any two systems with the same fine-grained functional organization will have qualitatively identical experiences. If the causal patterns of neural organization were duplicated in silicon, for example, with a silicon chip for every neuron and the same patterns of interaction, then the same experiences would arise. According to this principle, what matters for the emergence of experience is not the specific physical makeup of a system but the abstract pattern of causal interaction between its components. Thus, it seems to me that, if the brain is distorted as you described but still has the same fine-grain functional organization or the same causal patterns of neural organization (like Condition C in the previous paragraph), then Chalmers would predict that the conscious experience will be the same. On the contrary, if Condition C is not met, I think Chalmers would predict that the conscious experience will not be the same.

According to The Integrated Information Theory (ITT) [3-6], a conscious experience is a maximally irreducible conceptual structure (MICS), which corresponds to a local maximum of integrated conceptual information (or a local maximum of Φ or Φmax) at that point. It also provides mathematical formulations to calculate Φ [see ref 4,5]. But the mathematics is not easy and beyond my capability. However, something can be garnered from its plain language explanation of its concept: The ITT says that one should analyze the real physical components – identify elements (e.g., transistors), define their cause–effect repertoires, find concepts, complexes, and determine the spatio-temporal scale at which Φ reaches a maximum [6]. So, if Condition C above is not met, it’s very likely that the conscious experience will change (at least from the change of cause-effect repertoires). However, when Condition C is satisfied, I cannot tell in which way the ITT will predict the change of the conscious experience because other physical components that it lists might be changed.

Similarly, according to The Basic Theory of the Mind [7], a conscious experience is information in some specific form, i.e. a reentrant signaling state in some specific form, that means phenomenal consciousness in the neural process language, and according to The Adaptive Resonance Theory [8,9], a conscious experience is a neural process in a resonant state. Because, if Condition C is met, the signal-transmission effects of a neural circuit on other neural circuits remain un-altered, those reentrant signaling states or resonant states should remain the same. Thus, it seems to me that these two theories will predict that a conscious experience will remain un-altered too. On the contrary, if Condition C is not met, I think that these two theories will predict that a conscious experience will change.

In conclusion, I believe in the concept like the principle of organizational invariance, it’s the function that matters, not the anatomy.

Caution. “Thought experiment” is just a fanciful word for “what if …” scenario that we and other ordinary people form to make decisions every day. It is not physically carried out. So, unlike the results of physical experiments, the results of thought experiment reached by anyone can never be taken to be evidence for or against any concept or theory. They are just conclusions reached by individual’s arguments.

References.

  1. Chalmers DJ. Facing up to the problem of consciousness. J Conscious Stud. 1995;2(3):200-219.

  2. Chalmers DJ. Moving forward on the problem of consciousness. J Conscious Stud. 1997;4(1):3-46.

  3. Tononi G. An information integration theory of consciousness. BMC Neurosci 2004,5:42. DOI: 10.1186/1471-2202-5-42.

  4. Tononi G. Integrated information theory of consciousness: An updated account. Arch Ital Biol. 2012 Jun-Sep;150(2-3):56-90. DOI: 10.4449/aib.v149i5.1388.

  5. Oizumi M, Albantakis L, Tononi G. From the phenomenology to the mechanisms of consciousness: Integrated Information Theory 3.0. PLoS Comput Biol. 2014 May;10(5):e1003588. DOI: 10.1371/journal.pcbi.1003588.

  6. Tononi G, Koch C. Consciousness: Here, there and everywhere? Philos Trans R Soc Lond B Biol Sci. 2015 May 19;370(1668):20140167. DOI: 10.1098/rstb.2014.0167.

  7. Ukachoke C. The Basic Theory of the Mind. 1st ed. Bangkok, Thailand; Charansanitwong Printing Co. 2018.

  8. Grossberg S. Adaptive Resonance Theory: How a brain learns to consciously attend, learn, and recognize a changing world. Neural Netw. 2013 Jan;37:1-47. DOI: 10.1016/j.neunet.2012.09.017.

  9. Grossberg S. Towards solving the hard problem of consciousness: The varieties of brain resonances and the conscious experiences that they support. Neural Netw. 2017 Mar;87:38-95. DOI: 10.1016/j.neunet.2016.11.003.

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  • One of the questions for algorithm/structural theories of mind is -- one can transform any structure into another structure, with the appropriate transform function. why is consciousness associated with the structure plus transform in a brain, and not the structure plus transform of the drops on a window? and why not the structure of molecules in a room full of gas, or a set of stars scattered across the universe? The coupling to a particular co-located mass, and the lack of flexibility of transforms, are not explained by the algorithm/structure hypothesis. – Dcleve Jan 25 at 8:41
  • @Dcleve I think the answer is, according to Chalmers, what matters for the emergence of experience is not the specific physical makeup of a system but the abstract pattern of causal interaction between its components. Correct transformation of the brain, not of other things, can theoretically preserve this "abstract pattern of ..." that creates consciousness. So, theoretically, if the transformation does preserve this "abstract patten of...", it will preserve the energence of experience, the consciosness. – user287279 Jan 25 at 13:18
  • the question for your model is how "a pattern of causal interaction" creates consciousness, as wella s what a "pattern of casual interaction is", By Popperian falsification tests -- a "pattern of causal interaction" is just state sequences in an interacting collection, and all neural sequences, plus all patterns of gas molecule locations in a room, are "patterns of causal interaction". Yet almost none of these are associated with consciousness, rather than ALL of them! Algorithmic Identity Theory is -- refuted by test. Whenever it is specified well enough to test. – Dcleve Jan 26 at 7:57
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    @Dcleve No, I represent his view as I understand it, and I’ve tried to be clear about it. Please note the words I used in the answer above “Thus, it seems to me that, if the brain is distorted as you described, …. then Chalmers would predict that the conscious experience will be the same. On the contrary, if Condition C is not met, I think Chalmers would predict that ...”. I may not understand him correctly, but I didn’t assert that Chalmers predicted anything I posted or that these are his views. They are what it seems to me and what I think. – user287279 Jan 26 at 8:57
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    And why do you think that all patterns of gas molecule locations in a room are part of "patterns of causal interaction" that is associated with consciousness? One can pump out all the air in the room without affecting consciousness of a person in a room (at least for a second). Or the person can dive into the water and have no air surrounding him without his consciousness changed. This proves that all patterns of gas molecule locations in the room or of other things, except the brain, are not part of "patterns of causal interaction" that is associated with consciousness. – user287279 Jan 26 at 9:02
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This question, or at least one very like it, was one of the discussion chapters in The Minds I, by Dennett and Hofstadter. https://www.amazon.com/Minds-Fantasies-Reflections-Self-Soul/dp/0465030912 That book took a very playful approach to philosophy of mind, and I expect that you would enjoy it immensely.

Often the point of such what-if questions in philosophy is to show where other's unidentified assumptions are not really valid. The assumption here is reductive neural identity theory, and the challenge is that there is no obvious route using that assumption to get to either the correlation nor wholism we see in consciousness, and when you spread the neurons out, a reductive materialist who is glossing that failing over -- is more likely to realize these two shortfalls to their assumptions.

The two authors went in somewhat different directions -- Hofstadter jumped from neuronal to algorithmic identity theory https://www.amazon.com/Am-Strange-Loop-Douglas-Hofstadter/dp/0465030793/ref=pd_sbs_14_1/134-5020656-5151509?_encoding=UTF8&pd_rd_i=0465030793&pd_rd_r=278902e9-e094-44b1-ba2f-9e564189f36f&pd_rd_w=IvU0z&pd_rd_wg=KOl0Q&pf_rd_p=bdd201df-734f-454e-883c-73b0d8ccd4c3&pf_rd_r=4C1HW5HG2TK81WSP8DBX&psc=1&refRID=4C1HW5HG2TK81WSP8DBX , and Dennett went even further, as he thinks algorithmic identity doesn't work either, but he was unwilling to give up on materialism, so he denies we are conscious https://www.amazon.com/Consciousness-Explained-Daniel-C-Dennett/dp/0316180661/ref=sr_1_1?crid=2S1ZZ4HGERNUE&keywords=consciousness+explained+by+daniel+dennett&qid=1579933580&s=books&sprefix=consciousness+explained%2Cstripbooks%2C179&sr=1-1

There are, of course, NON-materialist theories of mind, and some of those can solve the problem your teleportation machine identified -- that of identity. Algorithmically or materially, we change radically over time, so ascribing identity to ourselves does not make sense materially. However, if one takes a dualist view, then one can postulate a spiritual essence to self, which gives self "thisness", and gives extremely effective meaning to continuity in time. For a reference, see: https://www.amazon.com/gp/customer-reviews/R18J8OJA7QPLKX?ref=pf_vv_at_pdctrvw_srp

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  • To be honest: I found Zuboff's tale somehow confused and too many thought experiments in one. And can you guess how the author's would have answered my question? – Hans-Peter Stricker Jan 26 at 8:05
  • I am sorry, who is Zuboff? Was that the existential comic? – Dcleve Jan 26 at 8:20
  • It has been too many decades, I don't recall how H and D answered their own thought problem on the dispersed neurons. the book was structured with philosophical short stories, then their responses. And their thought story DID note that the uniqueness of the separated neuron was -- suspect. As was the collective experience associated with now-separated neurons. – Dcleve Jan 26 at 8:27
  • MY answer is interactive spiritual dualism and evolution have tuned brains to interact with minds -- and we have no idea how well that process would hold up if we start dissasembling those brains. But one can reasonably infer that at some point the interactive coupling will break down catastrophically. – Dcleve Jan 26 at 8:27
  • Sorry, Zuboff was the author of the "tale of a brain" in The Mind's I -I guess the one you referred to. – Hans-Peter Stricker Jan 26 at 8:35

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