If the cortex is the sign of consciousness, then it suggests that all vertebrates with cortex have at least some kind of consciousness.
The cortex is the “organ of mind,” both conscious and unconscious aspects.
That phrase “organ of mind” was written by Wilder Penfield based on some 1,200 “open brain epileptic surgeries” conducted between 1920 and 1950. Essentially all of Penfield’s empirical claims have been confirmed in the long wave of high tech neuroscopes of the last 20 years.
If the cortex is the sign of consciousness, then it suggests that all vertebrates with cortex have at least some kind of consciousness. The most ancient kinds of consciousness are plausibly sensory, beginning with the olfactory and taste senses and emerging in mammals with vision, hearing, body touch. These conscious senses constantly interact with corresponding motor systems so that we can talk about sensory motor consciousness, which leads to voluntary control of waking actions.
This well established chain of inference strongly suggests that consciousness is not rare, it is not confined to human beings, and its evolutionary history and phyletic breadth across numerous animals is very great indeed. Neurobiologists have been telling us this, somewhat quietly, but very clearly. (See below.) This realization will certainly disturb some people, but the evidence is simply not questioned in biology and similar sciences.
Empirical studies of conscious brains has already had stunning medical and biological and psychological implications. For example, Steven Laureys on coma and paralytic pseudo-coma (with waking patients). Also the issue of animal consciousness, which is now wide open, at least for animals with cortex, which includes mammals, amnionts, probably fish (lampreys and perhaps zebrafish), but also creatures with a so-called “pallium,” which does not look like cortex in gross anatomy, but it is wired up like cortex histologically. So Ann Butler, Harvey Carton and others have published a consensus article proposing that the word “pallium” should be dropped for birds and reptiles, and “cortex” should be used instead.
Consider the perspectives of Gerald Edelman, Walter Freeman, and before that, E.R. John, and a little bit of Karl Pribram and Ann Butler:
1. There are no simple animals. The reason is that you get “Neural Darwinism” at all levels of organization, from genes to epigenetics to momentary cortical organization, which we experience subjectively as conscious.
2. The color cones of the human/macaque fovea are important for color detection, but they do not determine conscious color. That is now believed to be done in area V3/V4, according to a recent finding by Li et al (2017).
3. Conscious visual input has a different course of processing compared to identical unconscious input in the visual brain — as demonstrated by literally decades of research by the Dehaene and Changeux team at CNRS, and by the Max-Planck-Campus Tübingen team by Logothetis and Panagiotaropoulos on the macaque visual system, which is strikingly similar to the human visual cortex.
4. The ability to distinguish clearly between conscious vs. unconscious visual input, as in binocular rivalry — with identical physical foveal and retinal input in both ideas, that ability has been crucial in the last 20-30 years of research. Dehaene uses the attentional blink, but there are a dozen settled ways of comparing conscious-to-unconscious sensory input. You can do it with distraction, and one of the early studies by Rosen et al did it by comparing painful ischemia to silent ischemia.
5. We know with considerable certainty what the brain differences are (some of them) — between experimentally matched conscious and unconscious conditions in vision, in external body touch, in interoception (anterior insula), in audition, and now, in Feelings of Knowing, as in the subjective feelings of effort that have been studied since Wilhelm Wundt in the 19th century.
This phenomenon of subjective effort has been studied especially well by John Duncan and Adrian Owen in the UK. Beautiful work that converges well with the Five Factors of personality, where “conscientiousness” has to do with sustained feelings of effort in PfC, both medially and laterally.
6. The idea that we know nothing about consciousness is therefore a myth, a leftover from behavioristic denial.
If we have a choice between ignoring it and studying it, I would think scientists would study it. But residual behaviorism continues today — perhaps because the ethical implications are too mind-boggling. Scientists are human.
7. There is strong, convergent evidence from global states of vigilance in the cortex (both neo and paleo). This was already observed by Wilder Penfield early in the 20th century, based on 1,200 major epileptic surgeries with waking patients who talked to their surgeons during exploratory surgery, which was needed at that time to identify areas to avoid harming, and areas of cortex that were essentially dead and needed to be removed to stop major seizures.
Most of those surgeries were medically helpful, but HM (Henri Molaison) shows bi-lateral hippocampal neural cell death, and the decision was therefore made to excise hippocampal tissue on both sides. This left HM impaired, because the hippocampus is the first experiential memory system, and he had to live in the fleeting moment with no ability to use his conscious experiences to learn, solve problems, develop perceptual learning, and more. Dr. Brenda Milner took charge of his life. HM was studied for sixty years by multiple laboratories, and is still our primary human reference case for bilateral hippocampal excision.
This case is still medically controversial.
8. Penfield’s main goal was medical, and in that respect he and his team (from 1920s to 1950s) were successful enough to lead to a modern series of direct cortical surgeries in waking patients who can talk about their experiences with the surgeons. But Penfield also published several short articles which are very important even today. His primary claim is that cortex is the organ of mind.
Penfield was certainly not the only one to believe this, it was a general medical belief voiced by William James in 1890. But with 1200 cases, Penfield had by far the biggest archive of evidence. The Penfield archives at the Montreal Neurological Institute are still closed, to protect patient privacy. All we have therefore is the publications, which tell their conclusions and some illustrative anonymous cases, but not all the details. This may be one reason why Penfield’s work is still disregarded in science, but not in neurosurgery.
In the last few decades, waking neurosurgery has been revived, and we have 200 articles in the literature on various aspects. Yitzhak Fried has been one of the leading neurosurgeons who works with scientists like Christof Koch and many others on this. This material is easy to find on PubMed and Google Scholar.
9. The evident role of both kinds of cortex (neo and paleo) poses rather scary questions, notably the very ancient biological origins of cortex. Neocortex is routinely claimed to arise with early mammals. Paleocortex goes back to vertebrate fish. The leading edge science on these species is now rapidly being studied using the genome of lampreys and zebrafish.
It is believed that amnionts were the first land dwelling vertebrates who gave birth on land and also lived in a marine environment. Some amnionts looked a little bit like salamanders. The scientific ethical implications of these new facts are stunning. Pain perception is a survival function, and is therefore likely to be very ancient.
10. The implications for the ontogeny of conscious pain perception in utero are therefore very real. In utero pain can never be dismissed, and pain in fish can’t either. Sorry about that.
11. The idea that we don’t know anything scientifically about conscious brains is simply false. The evidence can be found via a simple search under “conscious and brain” in PubMed or Google Scholar. You may be surprised at the number of peer-reviewed excellent articles that show up.
12. The ethical consequences cannot be ignored. Scientists are not experts on ethics, but then neither are philosophers. Or anybody else, for that matter, although there are ethical debates on animal pain and killing that go back to hunter-foraging cultures. Hunters are generally aware of the fear and pain experienced by wild prey. Even cows, sheep, lambs, and chickens seem to show fear and alarm, and the brain evidence today shows they have cortex, and pallium in the case of chickens.
Ann Butler and other comparative neurobiologists have published a consensus paper to rename the avian and reptilian pallium “cortex.” The reason is that the microstructure of cortex is ultraconserved among birds and reptiles, and possibly even ancestral species. The gross anatomy of the pallium looks different, but careful histological studies show the strong similarity across large genetic taxa.
12. All of which leaves civilized people with a dilemma. But evidence is evidence is evidence. We can either face it or evade it.
The future of conscious AI
When computers started to populate the laboratories, the traditional rejection of unconscious thought was no longer viable. Contrary to widespread speculation, computers are not provably conscious. Empirically, we only know about conscious brains in the biosphere. That fact might conceivably change, but the burden of proof is always on the proposer. Because the science is still new and uncertain, it is inherently difficult to prove empirically that artificial entities are conscious. Computer programs that seem to act like conscious beings do not provide empirical proof.
The map is not the territory.
[Excerpted from Part I – Major Features of Conscious States and Contents & Consciousness in Philosophy and Science from Bernie Baars’ latest book “On Consciousness: Science & Subjectivity.”
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Global Workspace Theory (GWT) began with this question: “How does a serial, integrated and very limited stream of consciousness emerge from a nervous system that is mostly unconscious, distributed, parallel and of enormous capacity?”
GWT is a widely used framework for the role of conscious and unconscious experiences in the functioning of the brain, as Baars first suggested in 1983.
A set of explicit assumptions that can be tested, as many of them have been. These updated works by Bernie Baars, the recipient of the 2019 Hermann von Helmholtz Life Contribution Award by International Neural Network Society form a coherent effort to organize a large and growing body of scientific evidence about conscious brains.
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