By Mary Monro
Despite the best efforts of scientists and philosophers over the centuries, no mechanism has been discovered that indicates how consciousness emerges in the brain. Descartes famously thought the soul resided in the pineal gland - but that was mainly because he couldn't think of any other purpose for it (It actually produces melatonin and guides sleeping patterns). But, 400 years on, perhaps we still need to think again about where consciousness might reside.In recent years there has been a surge of interest in the gut brain, with its hundred million neurons and its freight of microbes, that influences every aspect of our being including mood and memory. If the gut might now be considered a possible source of consciousness what about other candidates?
After all, “Primary consciousness arises when cognitive processes are accompanied by perceptual, sensory and emotional experience” as Fritjof Capra and Pier Luigi Luisi put it in their book The Systems View of Life: A Unifying Vision (2014). Reflective or higher-order consciousness includes self-awareness and anticipation.
There is another intelligent, organising, feeling, planning, responsive, communicating organ inside us – a body-wide-web lining our blood vessels. Vascular endothelium cells (VE for short) line every vessel from the heart to the smallest capillary, reaching into every part of the body. Vascular endothelium is the interface between the blood and the tissues, deciding what goes where through a combination of electrical, kinetic, mechanical and chemical signalling.
Laid out, the VE in a human body would be the size of a rugby pitch yet it weighs only one kilogram. Far from being simply wallpaper, recent research has shown it to be a lead actor in the management of the body, including the brain. It is believed that each of the sixty trillion cells of the VE is unique, each one exquisitely adapted to meet the needs of its immediate environment, whether that is in the deeply oxygen deprived depths of the kidney or the highly oxygenated gas exchange surface of the lung. William Aird, in a scholarly paper in 2007, describes vascular endothelium as 'a powerful organising principle in health and disease'.
The blood-brain barrier (usually abbreviated to BBB) protects the brain from molecules and cells in the blood that might damage neural tissue. The vascular endothelium forms the interface but it was previously thought to be a passive sieve, controlled by neurons. The BBB has now been renamed the ‘neuro-vascular unit’ as it has become clear that neural cells, pericytes (that back the endothelial cells) and the vascular endothelial cells all actively take part in managing this critical barrier. It is not known which of them is in charge.
Other researchers have sought to apply the Turing Test to the VE in the brain – the Turing Test being an evaluation of whether an information processing system is capable of intelligent, autonomous thought. Christopher Moore and Rosa Cao, argue that blood is drawn to particular areas of the brain by the VE, in advance of metabolic demand, where it stimulates and modulates neuronal function. So the brain is responder rather than activator. Who is doing the thinking? Is the body-wide-web (including the heart and its assistant the blood) gathering information from the body and the external environment to tell the brain what to do? How does it make decisions? What does this imply for consciousness?
In fact, long ago, Aristotle asserted that the vascular architecture in the embryo functions as a frame or model that shapes the body structure of the growing organism. Recent research bears this out, with the VE instructing and regulating organ differentiation and tissue remodelling, from the embryo to post-natal life. The VE cells form before there is a heart and it is fluid flow that drives endothelial stem cells to trigger the development of the heart tube, vessels and blood cells. There is no brain, only a neural tube, at this stage.
Recent research has shown that blood vessels can direct the development of nerves or vice versa or they can each develop independently. So, embryologically, there is a case for saying that the VE is a decision making executive.
All this recalls a founding principle of osteopathy – which is that ‘the rule of the artery is supreme’. This is a poetic, 19th century way of saying that disturbance to blood flow is at the root of disease. In his autobiography, published in 1908, Andrew Still remarks: ‘in the year 1874 I proclaimed that a disturbed artery marked the beginning to an hour and a minute when disease began to sow its seeds of destruction in the human body’.
Now, almost a century and a half on, we find that ‘endothelial activity is crucial to many if not all disease processes’, as K. S. Ramcharan put it in a recent paper entitled ‘The Endotheliome: A New Concept in Vascular Biology’ (published in Thrombosis Research in 2011). All this illustrates the importance of this seemingly humble tissue, upon whose health our mental and physical wellbeing depends. And if this structure acts consciously, then perhaps we should consider the possibility that all living cells act consciously.
*Mary Monro Bsc (Hons) Ost, MSc Paed Ost, FSCCO is an Osteopath, based in Bath, United Kingdom.
16 comments:
A lot is uniquely attributed here to ‘vascular endothelium cells’ — especially in the framework of where human consciousness hypothetically emerges and resides. Much of great interest to think about, Mary. For me, however, it isn’t demonstrably clear how the roles of VE tissue get the conversation’s conclusion either to the notion that ‘this structure [the VE] acts consciously’ or, more sweepingly, to the notion that ‘all [tens of trillion] living cells act consciously’.
Is the thread between VE tissue and an understanding of the ‘mystery of consciousness’ (per the essay’s title) really that discernible and traceable? There’s no question that, as the essay assures, the VE is crucial to health. But might one make a similar assertion about other complex, physiological apparatuses of the human body that have similarly ‘exquisitely adaptive’ properties — though without the ambitious reach for a tie-in to human consciousness?
As to where consciousness resides, I wonder if the VE in the 21st century is the equivalent of Descartes’s pineal gland in the 17th century. Instead, what of modern-day neuroscience’s capacity — in conjunction with physics, biology, psychology, and philosophy — to lead to some aspect of the neurophysiology of the brain as the epicenter of consciousness? In which case, doesn’t the VE serve at most in an auxiliary role? And isn’t the brain therefore the ‘tissue’ that’s operating in what’s identified, above, as the strategically vital, combined roles of ‘responder’, ‘activator’, and ‘decision-making executive’?
Personally I would think that, for consciousness to exist, a conscious X needs to exist (largely) in isolation from the brain. The next question then is whether that X exists materially or immaterially. Is the proposal here that there is indeed an X which exists materially and (largely) in isolation from the brain? This is a very interesting piece.
Yes, Mary poses an old question for us doesn't she? It's all very well to say that we are conscious, but 'what' exactly is conscious? Is it all my cells... or is it the electrical activity in the brain... or the sum of all the interactions in the nervous system..?
I thought the article introduced a fascinating new aspect.
This is indeed fascinating. In particular "Christopher Moore and Rosa Cao, argue that blood is drawn to particular areas of the brain by the VE, in advance of metabolic demand, where it stimulates and modulates neuronal function."
"In advance of metabolic demand"!! What can I say, I need to read more about this. Thanks for alerting me to your article Martin.
I would speculate that one way to make sense of this is to bring up the microtubules, as described and understood by Stuart Hameroff. More later......
Published online at about the exact same moment:
Social stress induces neurovascular pathology promoting depression. Nature Neuroscience (2017)
doi:10.1038/s41593-017-0010-3
https://www.nature.com/articles/s41593-017-0010-3
Thanks very much, Perig! This is exactly the kind of insightful connection we value...
And even without it - great to see you pop in!
Hi, Mary here. Thanks for your comments about this. The more I have studied the vascular endothelium, the more intrigued I have become. I think we are fixated with the brain as being the source of consciousness and I just wanted to drop a stone in that pond. After all, it's never been proven. I believe that living creatures need to have intelligence, consciousness, everywhere in their being to be able to relate to their internal and external environments. What is consciousness for? One might ask. It was the functional hyperaemia - the blood supply in advance of demand - that really made me wonder about the brain's supremacy, especially as the blood brain barrier does not seem to be neurally controlled as previously thought. The vascular endothelium is a very active field of research, because of its therapeutic potential, so I shall see what new wonders emerge.
There are all shades of publications, written by scientists, mathematicians, and others, that present technical discussions hypothesizing where consciousness emerges from and resides. Obviously, many sources, from technical papers to TED talks to books, are based in neuroscience’s ambitiously broad sweep to understand consciousness. Those sources are easily found online and are, unto themselves, well worth chasing down given neuroscience’s role in addressing the neural correlates of consciousness, as well as much more. Among the long list of neuroscientists currently doing outstanding, recognized work in the field is Michael Gazzaniga, as just one instance.
But to venture even farther afield, simply googling terms like ‘quantum consciousness’, ‘strong free will theorem’, ‘orchestrated objective reduction (Orch-OR)’, and ‘mathematical theory of consciousness’ can start a fascinating examination into where some very bright, visionary people have been going with the subject over the years. Some of the resulting papers are more or less technically dense — that is, degrees of approachability — than others. And some among the sundry hypotheses have, notably, gained or (indeed) lost credibility over the years — with none yet ready for prime time, absent a eureka moment to be announced by newspaper headlines. Regardless, searches on a variety of terms help to get one beyond the well-trodden, standard hypotheses.
I hesitate to provide links, so as not to bias the search.
Thanks for your comment, Mary, stressing again the broad issues.. and Keith for your suggested 'homework'! Myself, though, I think the scientists are missing the issues in their attempt to 'pin point' consciousness... psychologists and social scientists know how what we think depends on a broad net of relationships external to our bodies. We've all heard of the disorientation people suffer when depreived of all sensory inputs, but understanding the sensory inputs is presumably a social process and not just a solitary one.
Hameroff/Orch-OR has pointed out since the beginning of his research that paramecia are capable of learning, finding mates, etc, exhibit what appears to be (proto)consciousness although they have no new neurons. I think that a good place to start is those structures, microtubules, because they are everywhere and could be capable hosting quantum coherence.
"Single cell organisms like Paramecium swim about, avoid obstacles and predators, find food and mates, and have sex, all without any synaptic connections. They utilize cytoskeletal structures such as microtubules (in protruding cilia and within their internal cytoplasm) for sensing and movement. The single cell slime mold Physarum polycephalum sends out numerous tendrils composed of bundles of microtubules, forming patterns which, seeking food, can solve problems and escape a maze (e.g., Adamatzky, 2012). Observing the purposeful behavior of single cell creatures, neuroscientist Charles Sherrington (1957) remarked: “of nerve there is no trace, but perhaps the cytoskeleton might serve.”"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3470100/
"We've all heard of the disorientation people suffer when depreived of all sensory inputs": yes, the ganzfeld experiments and the sensory deprivation tank (featured in the series Stranger things), which both suggest that consciousness is constrained, not made possible, by the body!
"Single cell organisms like Paramecium swim about, avoid obstacles and predators, find food and mates, and have sex, all without any synaptic connections."
In effect, you're suggesting they're not only conscious but purposive? But then we seem to have to start having greades of purposive behaviour, no? I always think of trees as having 'rights', and 'preferences', but I still supsect there is some sort of 'jump' to the higher mammals...
Yes, I would say that they have intentions. Because I also adhere to Bohm's view of particles, that they have something guiding them that is a kind of information, I would say that purpose is everywhere (intelligent design!!) and that there are several jumps, several level of purposive experience.
What strikes me both in the post and in your comments, Perig, is just how little we have understood -- and that which we understand now seems likely to be eclipsed by things yet to come. The reductionism of the past seems so bare.
If only! I remember Kierkegaard's parodying of the philosophers: "the system is almost finished, or at least under conscruction, and will be completed by next Sunday"
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