someone's studying cephalopod consciousness

Discussion in 'Behavior and Intelligence' started by monty, Jan 13, 2008.

  1. monty

    monty Colossal Squid Staff Member Supporter

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    This seminar announcement for a talk at Caltech sounds interesting:

    http://today.caltech.edu/eas/item?calendar_id=77467&template=cns

    I'll report more after I go listen, but I figured it's interesting that the modern "trendy neuroscience" studies of "consciousness" have started to study cephs. This is particularly interesting since much of the brain parts that describe mammal consciousness don't even exist in cephalopods, so it sounds marvelous from a perspective of understanding convergent evolution, and common characters in diverse brains that serve the same function, etc.
     
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  2. Tintenfisch

    Tintenfisch Architeuthis Staff Member Moderator

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    Cool, looking forward to hearing how it went!
     
  3. scottwolverine1

    scottwolverine1 Pygmy Octopus Registered

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    Convergent evolution to what other animal?
    -Yes,this could be very interesting,please do keep us updated.

    Though,it may be to complicated for me.I'm still wrestling with the idea of Crocodiles having a cerebral cortex and a four chambered heart,unlike every other reptile.
    -Cephalopod intelligence is on another level understanding
     
  4. monty

    monty Colossal Squid Staff Member Supporter

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    I was thinking convergent evolution of cephalopods and vertebrates in general. Arguably, arthropods and worms and snails might have "consciousness" of a sort, but even within the molluscs, cephalopod nervous (and circulatory) systems are much more sophisticated than any other mollusc, and presumably the last common ancestor with vertebrates or arthropods was some flatworm-like thing with a very limited behavioral repertoire, so any sophisticated behavior, consciousness, or intelligence, or even brain anatomy that cephalopods share with vertebrates is convergent evolution... and when the anatomy is extremely different yet the function is the same (learning, deciding, perceiving, communicating, or consciousness) cephalopods are a great, and in many case unique, example of a different nervous system layout providing somewhat similar behaviors and abilities to vertebrates. Most neuroscience talks about cortex, and hippocampus, and sometimes cerebellum and spinal reflexes, all of which are completely absent in cephalopods, and while there might be some very rough correspondence (the visual lobes might play a role sort of like visual cortex, and the vertical lobes seem involved in learning and memory, so maybe they could be considered homologous with the hippocampus) in most ways, cephalopod brains have developed from different roots, although, of course, they've had to compete with vertebrates for quite a while, so they've had pressure to develop systems that can overcome vertebrate (and crustacean) predators and prey.

    And it's always amazing to me how some pre-cambrian proto-metazoan locked in a lot of the body-plan and cell-differentiation types that are used in all eumetazoans (and probably all metazoans, but I don't know that much about sponges) and often single-celled eukaryotes and even bacteria... so one can probably assume that the first primitive mollusc got a whole lot of stuff inherited from far earlier, before the protostome/deuterostome split for sure... that's (presumably) why we can study squid giant axons' ion channels, and squid and fruit fly and sea urchin homeobox genes, and octopus visual pigments, and find that they're identical, or almost identical, to the ones used in vertebrates.
     
  5. scottwolverine1

    scottwolverine1 Pygmy Octopus Registered

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    1)Convergent evolution.
    -Thanks for explaining that,it makes more sense now.

    2)Intelligence at the basic level
    -There was a show called "human version 2.0" that came on the science channel that was interesting.It (kind of) relates some of the finds mentioned involving basic neural networks to neuronal/brain functions of lower order organisms.

    Flat worms?
    -I remember my freshman (anatomy and physiology) professor mentioning that one could grind up "trained" flatworms and feed them to untrained ones and they somehow "remembered" how to transverse the maze better.
    -That was years ago,I never followed up on that one.

    4)You said....."so they've had pressure to develop systems that can overcome vertebrate (and crustacean) predators and prey".
    This is off topic a little,but you might find this interesting.

    From that book {The Ocean World}...Octopus-lobster-moray eel are three couples with built in animosities.Mediterranean fishermen tell stories of traps that they pull back to their boats,sometimes containing an octopus,a lobster,and a moray eel:the three retreat to the three corner of the trap as far from the other as possible,because they know the first one to attack will be immediately killed by the third party.

    I wish I had a deeper understanding of A+P to comment more on your reply.
     
  6. Tintenfisch

    Tintenfisch Architeuthis Staff Member Moderator

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    :yuck:
     
  7. monty

    monty Colossal Squid Staff Member Supporter

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    Well, whenever I grind up the people my assistant Igor brings me and try eating them, I just get the villagers chasing me out with those wooden pitchfork things, and the occasional case of kuru.

    Actually, I'm pretty much kidding on that, but I heard about the "grind up planarians to pass knowledge" thing in High School, but I don't remember learning about it in neurobiology or comparative nervous systems classes I took in college.

    This page has some suggestions that the experiment may have been flawed in a number of ways, but also mentions some followup results. I'm pretty dubious, since RNA hasn't been implicated in memory in any way I'm aware of in "real neuroscience" and I'm not clear on the proposed mechanism... I'm not too knowledgeable on the digestive systems of flatworms, but in vertebrates or cephalopods, I wouldn't expect neural tissue or RNA to survive the digestive processes intact enough to convey any information.

    p.s. the lobster/eel/octopus thing is pretty interesting... kinda "rock-paper-scissors" or "the good, the bad, and the ugly" final gunfight. With no shelter in a closed space, I'd have to lay odds on the eel, the octopus, and the lobster in that order, as much as I'd be cheering for the octopus...
     
  8. Taollan

    Taollan Vampyroteuthis Supporter

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    Interesting, I am very in hearing how this goes. With the wide variety of non-human explorations of consciousness he is refering to, I wonder if the cephalopod consciousness work is his own or if he is citing the work of Dr. Jennifer Mather. I attended a lecture by her a couple years ago entitled "To bodly go where no mollusk has gone before: personalities, play and consciousness in cephalopods", which was very interesting. This year she published in Consciousness and Cognition and article entitled "Cephalopod consciousness: Behavioural evidence." (abstract can be found at http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&uid=17240163&cmd=showdetailview&indexed=google)

    Oh, and:
    Thanks monty for giving a nod to the circulo-respiratory physiology side of cephs. Its' incredible features are often is lost in all the talk about their behavior, which I must admit, it a much more sexy area of their biology.
     
  9. monty

    monty Colossal Squid Staff Member Supporter

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    Hmm, where to start... this was a very fascinating talk. The part related to cephalopods did not have too much new detail I was unaware of, but was a fantastic introduction to the capabilities and style of the ceph nervous system, and why it these are great animals to study to as a comparative consciousness study, and it seemed to get the attention of a lot of the neuroscientists who attended. I spoke briefly with the speaker, David Edelman, afterwards, but since he had a lot of real neuroscientists waiting to talk to him, I said I'd follow up with him later by email. He was well aware of TONMO, and gave some high praise, and I encouraged him to stop by and participate. (That being said, I'm all nervous about trying to do his wonderful talk justice in this summary-- I tried to take good notes, but some of the slides went by pretty fast... I saw hallucigenia there, who can perhaps correct any gaffs or omissions, hint hint.)

    The talk covered a number of interesting areas, starting with a brief discussion of "what is consciousness" (a popular topic around Caltech, since it's a favorite topic of Christof Koch) and the history of that question. Behaviorists like Skinner have guided neuroethology and the like away from asking questions about things like "mind" and "consciousness," so for a lot of the 20th century it was more studied by philosophers than neuroscientists. There also have been serious technical hurdles on the subject, since it's hard to measure, describe, monitor, and so forth. Much of what modern studies of consciousness have been based on in humans is their own reports of what they're subjectively experiencing about their state of mind ("metacognition"), which, of course, can't be done with most non-human animals (with the possible exception of great apes like Koko and the late Alex the parrot.)

    He had a slide of a long list of things related to consciousness that I didn't fully copy, but they range from purely subjective to very physiological but rather primate-oriented (the reference is Seth et. al. 2005 Consciousness & Cognition 14:119-139, where Edelman is part of et.al., I'm going to see if I can download that one shortly.) We understand some of the parts of the brain, like cortex and thalamus, that seem to be involved in human consciousness, but we see what appears to be consciousness in animals that don't have those brain parts at all.

    Consciousness seems to involve the ability to integrate multiple modalities of sensory input with memory, learning, and behavior, and the sorts of things that he thinks we should be looking for as general mechanisms for consciousness include this cross-modal sensory input, feed forward signaling across the cortex (or the equivalent part) and "reentrant signaling." It also seems that consciousness often involves regional long-term potentiation as a form of memory, and widespread, fast, low-amplitude electrical activity in the brain, which is sort of a fancy way of saying "thinking and memory of what was thought" if I understand it correctly. In any case, he believes we should be looking for analogs of the mammal thalamocortical system in other animals, such as birds and cephalopods.

    He also touched on some ecological aspects that I'll mention since I can look clever for mentioning some in my post before the talk :roll: -- a heterogeneous ecology, predator/prey arms races, and hierarchical social ecologies all seem to be ecological pressures to develop consciousness. He also noted that octopuses are interesting in that last one, in that they are generally solitary and don't communicate so much with others of their own species.

    The next part of the talk discussed various animals that have been studied: vocal learning has been shown in marine mammals (both cetaceans and pinnipeds), birds, and bats, and manual learning (like sign language) has been shown in primates. There was then a history of trained primates, like Koko the signing gorilla and Alex the parrot, which I'll skip the details of.

    Then he mentioned that animals with "simpler" nervous systems show quite sophisticated behaviors, mentioning fruit flies, bees, jumping spiders, and octos-- I'm sure Roy would encourage him to add stomatopods to the list, too. He also discussed some robots that could do things like play soccer or navigate mazes with thousands of neurons and millions of connections, which sounds like a lot but is far less than are present in all but the simplest animals... in particular, the maze-solving "Darwin Machine" robot has its nervous system connectivity modeled roughly on the hippocampus.

    The next section was about birds, with some emphasis on ravens, which show some rather sophisticate behavior like solving puzzles involving pulleys and ropes to get their food, and keeping track of which other ravens may have seen where they stashed their food and which ones haven't, which they use to decide how to defend their hidden snacks ("I can't let that guy get close; he knows where I hid my lunch!") which is surprising in that it suggests the raven has an idea of what the other raven is thinking.
    (The reference for the Raven stuff is Scientific American, 2007, Heinrich & Bugnyar preview here and a book by Heinrich.)

    To me, although the bird part was interesting, one of the observations made it less so than for cephs: although bird brains look anatomically somewhat different than mammal brains, when one studies the homeotic gene expression in their development, it suggests that there are a lot of homologies between parts of bird brains and parts of mammal brains that seem to have the same function, suggesting that their original form, including primitive consciousness, were probably common in a shared ancestor.

    There was a bit of discussion of Alex the parrot, too.

    Then, finally, on to the cephalopods!

    He mentioned a number of the "classic" results, including J.Z. Young, Wells, and such, and discussed the recent work on the shoulders of those giants by Fiorito & Chichery and Hochner. He has been working with Fiorito in particular, it would appear, and he also had quite a number of excellent videos from Hanlon, several of which I hadn't seen before. There's also a video from Fiorito I'd love to track down of an octo doing the classic "crab in a plexiglass box" trick but with the twist that there are 3 lids it could unscrew, but only one opens (and one with no crab, where the octo decides to open it and check anyway, not trusting its eyesight, cause the researcher wouldn't be so mean is to give the box without a crab, would they?)

    Several of the interesting studies mentioned, some of which we've discussed before around TONMO, include Hochner's studies of arm behavior (including amputated arms :sad:) and using the bend of an "elbow" to "reel in" prey captured at the tip (I didn't know that the bend is generally at the same place even in a severed arm, suggesting the decision is made in the arm's nervous system more than the brain.)

    Also, Fiorito has now apparently developed a technique for neural recording from an electrode in the brain of a free-swimming octopus, and has found some interesting results there: a brain region that may be a hippocampus analog (I think it was in or next to the vertical lobe, but I need to look it up) and that there are single sites in the brain that respond to multiple tactile sites for stimulating the octo's body (like poking it), and that electrically stimulating brain regions can elicit a lot of behaviors-- primitive stuff compared to mammal electrophysiology, but starting to get on the right track of reproducing what's been done in fish and mammals. So far, there's no evidence that octos have a somatoropic map the way that mammal motor and somatosensory coretex works, but that might be more because we don't know what we're looking at than because it's not there (in fact, it's hard to imagine how a cuttlefish could map its visual world onto its chromatophores without a map from the optic lobes a somatotropic map on the cromatophore lobes.)

    Apparently, there is also a laminar (layered) organization to the vertical lobes that might be similar to that in mammal cortex in some ways, and the connectivity around there is similar to the thalamus and cortex (and maybe hippocampus?) in mammals in some ways. Also, Fiorito has found long-term potentiation, an important building block of memory and learning in mammals, in the vertical lobes of octopus in vitro, in prepared slices. There is some evidence that this is convergent evolution rather than something present in the shared ancestor, since it's physiologically similar, but biochemically isn't NMDA-dependent as it is in vertebrates (essentially, it's doing the same thing but with different chemicals.)
    (cont)
     
  10. monty

    monty Colossal Squid Staff Member Supporter

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    talk description continued

    (continued from above-- it was too long)


    He then moved on to the chromatophore system, where he appears to have been talking with Dr. Hanlon a bit... I learned that the chromatophore system involves Glutamate and 5HT (Serotonin) as neurotransmitters, both of which are found in the nervous systems of all (or almost all) animals that have nervous systems. He proposed a challenge of cephalopod psychophysics to look for hallmarks of consciousness like feedforward signaling across the cortex analog and reentrant thalamocortical circuits (no, I'm not completely sure what either of those means, either) and I either got to suggest that I'm clever or pretentious by pointing out that his proposed experimental setup had a bit of a bug: he's like to have LCD monitors show a picture of a squid to another squid, and try to get some communication going, and watch the results, but I suggested that may be more difficult than one might think, because it's known in octos and cuttles that they include polarization in their communication, and LCDs are all polarized in the same direction, while CRTs are randomly polarized, so a simulated animal may look similar to us but completely wrong to another ceph that can see the incorrect polarization. Of course, it's still an interesting question whether the ceph could learn to communicate with intensity and ignore polarization, just as we can learn to interact with not-really-believable fake-humans in video games....

    I was (of course) sad that he moved on to the conclusions at that point, summing up that he thinks that it's possible and useful to study consciousness in diverse animals, and adding notes that we should look for systems analogous to human cortex and other brain parts that seem to control our consciousness, that the behavior in the lab may be different from what's seen in the wild (so we should look at both) and we should study as wide a range of animals as we can find that show signs of "consciousness" in order to get a broad understanding of what that really means.

    In case it's not obvious, I really enjoyed this talk, and I'm quite enthusiastic. I also encourage Hallucigenia to mention anything I've forgotten, and hope Dr. Edelman himself might stop by to comment.

    Some things that didn't fit into the above description but might be of interest: I mentioned Robyn's work with nautilus, since he was mentioning that coleoids are more interesting in this regard than nautilus, but it sounds like Robyn's proven that nautiluses shouldn't be held in low regard in this area either. Also, he gets points for mentioning that firefly squids have 3 photopigments. I also suspect that he might want to augment some of the videos he showed from Hanlon's lab with some from Roy and Chrissy, since I think the walking-coconut-aculeatus would have fit in quite well, and Roy's recent videos of chromatophores on octopus hatchlings would have helped explain how chromatophore anatomy worked to those in the audience unfamiliar with that.
     
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  11. sorseress

    sorseress Colossal Squid Supporter

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    Wow Monty, did you have your laptop to take notes on? It really sounds fascinating. Thanks for going (had to really twist your arm, I bet) for your copious notetaking, and your (ahem) massive wall of text!
     
  12. monty

    monty Colossal Squid Staff Member Supporter

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    My pleasure (duh!) to provide the patented "wall o' text." I am actually a Luddite and still take notes on a pad of paper on a clipboard... I know it's very 20th-century of me.

    I should probably apologize a bit for tossing out some intimidating vocabulary, but I'm not quite up to making a glossary for the post, so people who haven't had university-level neuroscience classes might need to do a bit of wikipedia reading for the terminology, or should feel free to ask "what the heck does homeotic gene expression mean?" or whatever... but having reverted from "enthusiastic writer" to "lazy git" I'll wait 'till people ask, and maybe until some of the real biologists step in with better answers than I would have given anyway :grin: But I hope it's thought-provoking reading, at least...
     
  13. cuttlegirl

    cuttlegirl Colossal Squid Supporter Registered

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    Interesting stuff, I am going to have to reread your "wall o' text" but it is nice to see scientists using cephalopods to explain some vertebrate-centric systems.
     
  14. Tintenfisch

    Tintenfisch Architeuthis Staff Member Moderator

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    Yes, thanks heaps for your detailed transcription. Most fascinating!
     
  15. Daremo

    Daremo Cuttlefish Registered

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    Wow, thanks Monty. I read a lot of Edelman's work while working on my undergraduate degree, and as I recollect, "feedforward signaling" simply refers to the initial transmission of a signal to a given area (as opposed to feedback coming from the area), and "reentrant thalamocortical circuits" refer to the loops between areas of the thalamus and the cortex along which information is passed back and forth in a sort of ping-pong way, and is modified with each pass.
    I note there is no mention of the common distinction between "primary conciousness" (a basic awareness of one's surroundings, generally thought to be shared with many, if not most, other animals and "higher order conciousness," which is often thought (anthropocentrically) to be the province of Homo sapiens alone; so I presume that he focused on primary conciousness.
    I also recall reading (I think in some of Hanlon's work) about an octopus that apparently learned how to open a jar by watching an octopus in an adjacent tank learning that task, and then did it on the first try when presented with the jar itself. This sort of learning implies quite sophisticated mental processes, and would be very exciting to follow up on!
    Thanks again for sharing that!
     
  16. OB

    OB Colossal Squid Staff Member Moderator

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    Logic based problem solving, often thought of as a part of higher order consciousness, is certainly not restricted to Great apes (i.e. Homo sapiens); birds of the Corvidae family often show remarkable skills to said extent. Kat, Steve and other (honorary) kiwi's will be pleased to hear that especially New Caledonian Crows (Corvus moneduloides) show remarkable skills and innovations in tool use etc.

    Edit: Monty, you already mentioned this in "The Wall"
     
  17. monty

    monty Colossal Squid Staff Member Supporter

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    You guys are doing great at nailing me for missing parts of the talk in my summary....

    Dr. Edelman did, indeed, cover primary vs. higher order consciousness, and mentioned that the talk was, er, primarily about the primary type. Also, I guess I was vague that the pulleys and ropes were an example of ravens using context-dependent logic to pull up food: pull upward when it's at the end of a dangling rope, but pull downward when the rope goes up, over a pulley, and then down to the food.

    I think you're right on the general terminology, of the "feedforward" vs. "reentrant," but I think there's some subtleties in the way the terms were being used (but I may be wrong.) Interestingly, around 1987-1990, I ran into this sort of thing a lot in artificial neural networks (Hopfield's feedback nets vs feedforward nets like Minskey's "perceptrons") but not so much in my neurobiology classes... but it sounds like some of the usage of "reentrant" in particular is a particular type of feedback that is superimposed on the feedforward style that's common in sensory cortex, for example (I'm probably too rusty on thalamus and hippocampus to have an opinion.) David Edelman did mention that some of the terminology originated with Gerald Edelman, who's his father, and is at least mentioned in Topobiology-- in that context, it seems to be specifically proposed as the mechanism by which intelligent organisms can make associations between different sensory modes (like visual and tactile) and that there must be an underlying feedback system that allows correlation with those, both in real time, and via memory of having encountered the thing that's being observed before. I'm still rather vague on the details of the link there from functional to neural connectivity, but it sounds like there's been at least some discovery of the underlying mechanisms of that in vertebrates, and that looking for similar connection patterns in the very-anatomically-different cephalopods that can perform the same tasks would be interesting. I'm pretty sure that it's more specific than just "some sort of feedback mixed into the feedforward sensory system," perhaps more "a feedback system that seems to connect the same stages of perception to an integrator for memory and cross-modal correlation" or something like that :bonk: perhaps (hint, hint) Dr. Edelman will clarify this if he stops by...
     
  18. OB

    OB Colossal Squid Staff Member Moderator

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    This is truly good stuff, Monty.
     
  19. Daremo

    Daremo Cuttlefish Registered

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    Alas, then come the disputes about whether logic based problem solving actually requires the "awareness of self" of higher-order conciousness, or is simply the result of analyzing the environment, without that further "layer." Personally I have little patience with such nit-picking, unless there is evidence to support it, but it is all-too prevalent in the psychological literature. Behavioral Biologists are generally more sensible about such distinctions, which is a relief.
    Sorry, Monty, I didn't intend to "nail" anything; I really enjoyed you write-up. A lot of the terminolgy from the artificial neural networks is being introduced to attempt to describe what natural neural networks are doing, and I suspect that sometimes it is less appropriate than we think. I suspect that current ideas would say the reentrant mechanisms are more "overlying" than "underlying," based on their penchant for equating more generalised and wider-reaching association areas with "higher" levels of functioning (secondary and even tertiary processing centers), but I share your general sense of what they are proposing. It seems likely that the "some sort of feedback mixed into the feedforward sensory system" to which you refer is the multiple pathways which loop through and link various processing centers (one of my profs called it "loops within loops within loops"). I would love to see how those loops compare to the processing in the cephalopod CNS, which, as you say, is so very differently organized. I, too, hope Dr. Edelman will have more to say on this subject. Thanks again.
     
  20. Dave Edelman

    Dave Edelman Pygmy Octopus Registered

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    Hello, Monty and all other members of Tonmo. First of all, I want to thank Monty for the great review--and excellent summary--of the talk I gave at Caltech a couple of weeks ago. I think I enjoyed giving the talk as much as Monty enjoyed attending it!

    Monty's synopsis of the major points I made was dead-on, but I'll reiterate the most central ones to keep potential extensions of this thread on point:

    1) Owing to the influence of the American Behaviorist school (initially more theoretical; later, more methodological), as founded by John Watson and B.F. Skinner, the scientific study of consciousness was largely off the radar for much of the twentieth century. It's only been within the last 15 or 20 years that researchers have begun to revisit the field.

    2) Based on findings from the study of conscious humans (both healthy and brain-damaged), it seems clear that certain anatomical regions (e.g., cortex and thalamus) and electrophysiological signatures (widespread, low-amplitude electrical activity in cortex) are important in the generation/maintenance of mammalian conscious states.

    3) Contrary to traditional--and largely obsolete--nomenclature, bird brains contain "higher" structures that are homologous to those found in mammals (i.e., the avian hyperpallium corresponds to mammalian neocortex). Moreover, the genetics of avian brain development resembles that of mammalian brain development. Finally, many birds seem to be capable of quite complex behaviors (tool manufacture and use, logic-based problem solving, etc.) involving planning and even formulating predictive schema based on a "theory of mind"--that is, what the other guy could/might do. Given all of this, it wouldn't be a stretch to argue that birds are probably conscious; at the very least, the prospect and/or nature of avian consciousness is well worth investigating.

    4) The principles underlying the generation of consciousness may not be confined to vertebrate groups. Clearly, specific evolutionarily conserved vertebrate structures and their electrophysiological interactions are at the core of conscious states. But it is possible that certain key vertebrate electrical properties and functional neural circuitry have analogs within the nervous systems of some invertebrates. Although mammalian and avian brains share deep genetic, anatomical, and physiological homologies, such homologies--at least at the level of gross observable structure--may not be required for consciousness. Rather, it may be that functional analogy is important here. For example, while one wouldn't find cortex or thalamus in jumping spiders, octopus, cuttlefish, or squid, it is possible that functional equivalents of such structures exist in these vertebrates. And, following from this, if such functional analogs exist, one might find evidence of interactions between them, in the form of signature electrical properties, that resemble those recorded from mammalian brains during conscious experience.

    5) Given the overwhelming evidence for the behavioral complexity of many cephalopods (which, of course, I need not go into in detail for this group!), as well as recent evidence for the presence of something in the octopus vertical lobe that looks very much like long term potentiation (thought by many to be a fundamental physiological basis for learning in vertebrates), I believe that this group of animals bears further scrutiny by consciousness researchers.

    6) Perhaps the most critical point I tried to make in my talk is the idea that consciousness could have arisen convergently within at least a few--quite disparate--animal radiations. Certain principles of gross inter-areal wiring (thalamocortical analogs), activity across circuits (e.g., widespread, low amplitude electrical activity, the functional mappings discussed by Gerald Edelman (yeah, my dad) in the books Neural Darwinism, Topobiology, and The Remembered Present, etc.), and finally, the manner in which variable and rapidly changing input from convergently evolved complex sensory structures such as eyes (particularly eyes!) gets processed and integrated may in fact be universal among [sufficiently] complex nervous systems. In sum, given enough time and a sufficient elaboration of complex ecologies in which sensory and motor adaptations (i.e., speedy detection, speedy movement) among predators and prey are under intense selection pressure, I think it's a fair bet that consciousness emerged in diverse animal forms on more than a few occasions.

    Now to a couple of important bits that I didn't really cover:

    First, some important things to consider when thinking about the evolution of nervous systems:

    First, the world is an unlabeled place.

    Second, no two signals are exactly the same across time or space, whether perceived by different nervous systems or by the same nervous system at different times. That is, the qualities of the physical world are constantly shifting, subtly or not so subtly. By their nature, nervous systems parse signals into categories of "same" or "different"; in effect, nervous systems impose meaning on the world, not vice-versa.

    Third, in complex animals (think perhaps beyond the level of, say, C. elegans), no two nervous systems are exactly the same, even those of identical twins (clones). Myriad epigenetic interactions during development assure such individuality. So, for example, neurons never undergo arborization--they never connect up--the same way twice.

    So, now we have a bit of a matching problem. How do highly individual, idiosyncratic, nervous systems interact with a constantly shifting world--a category-free continuum--and successfully do the things they need to do to maintain survival?

    Here, I think, is part of the answer:

    Starting about thirty years ago, my father, Gerald Edelman, suggested that, in brains comprising vast and degenerate repertoires of neurons that are hyper-densely wired together, higher functioning (learning, memory, and even consciousness) emerge via principles akin to Darwinian evolution. Over the years, the Theory of Neuronal Group Selection (TNGS), or "Neural Darwinism" has been elaborated upon, to some degree; more often than not, though, it has been met with vocal, and often caustic, criticism. In any case, here's a "nutshell" precis:
    By birth or shortly thereafter, the nervous system comprises a vast primary repertoire of wiring combinations that has been shaped by epigenetic interactions during development. As an animal interacts with its world--maybe quite randomly at first (think of a flailing baby)--that world selects for particular functional sets of neurons; clusters of neurons that perhaps responded more quickly or efficaciously than others to salient stimuli (To a degree, one might think of "salience" as the one aspect of the system that is hardwired, in the sense of some very basic properties, such as extreme temperatures and eating vs. not eating, having evolutionarily programmed negative or positive salience; so, complex brains might have emerged with specialized salience detectors that regulate synaptic strengths "up" or "down" among/between neurons in "higher" centers like cortex). The synaptic connections between neurons in the selected clusters become strengthened. As a result, the next time a similar stimulus is presented to the animal, the likelihood of the same cluster of neurons firing together is much greater (think, "fire together, wire together"--a phrase most associated with Donald Hebb). At this point, a secondary repertoire emerges consisting of the functional groups that have been selected over the course of the animal's experience.

    The nice aspect of such a system is that its strength is really in its degeneracy. That is, if the wiring of brains was point-to-point and quite specific (like a digital computer), it's hard to see how such brains could deal with the vast amounts of novelty they would encounter continually in the [unlabeled] world. A selection-based nervous system, in which no two neurons are exactly alike and no two circuits are identical, would seem to be able to handle novelty much better than a system in which constituent elements are identical and there is a hyperspecificity of wiring patterns. As is the case among evolving populations of animals, too much specificity--or specialization--is probably a bad thing over time; less specificity--or degeneracy--is ultimately a good thing.

    In all of the foregoing, the notion of "degeneracy" is really critical. This is the idea, again, that there is no exact duplication, either in the phenotypes of individual neurons or in the functional circuitry of whole nervous systems. Think of this as a pool of variation that allows for a rich repertoire of neuronal interactions from which experience can select the "right" combinations of neuronal connectivity. It's very much like Darwin's notion of "species" (e.g., groups of [interbreeding] organisms that, while resembling one another, show a fair degree of variance).

    I won't make the jump from selection-based brains to consciousness today--I've babbled on far too long as it is. But consider this idea as the basis for my optimism that cephalopod brains--though not nearly as complex as mammalian brains--are sufficiently complex to yield the sort of interactions among vast repertoires of functional neuronal groups that is necessary--and sufficient--for the emergence of conscious states.

    Oh, one more bit: Daremo's question about comparing reentrant pathways (i.e., thalamocortical connectivity) in mammals to the anatomy of the cephalopod CNS is a really good one. Honestly, given the difference in CNS organization, it is hard to know where to look for such functional circuitry in cephalopods. But, as they say, "I'm on it like a cheap suit." Hopefully, we'll be able to say something about this in the near future.

    For now, 'nuff said. Thanks for reading my screed!
     

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