Why are we here? This is certainly humanity’s penultimate question. Even given all the wondrous advances of the human race to date, we are still completely blind to the answer – assuming there is one. People from all walks of life, physicists, philosophers, mathematicians, theologians, psychonauts, neuroscientists, will all give you there views on the matter, but of course, nothing is concrete. Regardless, undertaking the ultimate quest for knowledge certainly speaks volumes about the character of the human race. I’m not here to venture an answer to the question, but keeping in step with the topic, I will discuss a controversial theory of mind, in the hopes of continuing a conversation, on the how are we here question.
This brings me to one of the major unanswered questions in cognitive science, “the hard problem of consciousness”, which is by no means a misnomer; in short it aims to answer the question of how our physiology is able to give rise to the complex, highly subjective experience that is our conscious awareness and expression. As one can imagine, this question can be approached from a whole suite of different perspectives and has peaked great minds from all walks of life; from here on out, I aim to focus solely on two of these great minds. In the mid- 1990s, Sir Roger Penrose, a brilliant (understatement) mathematical physicist, and Stuart Hameroff, a prominent anesthesiologist, jointly put forth a very controversial theory aiming to elucidate the hard problem of consciousness. Penrose, having a strong interest in the underpinnings of the brain, aimed to build a quantum mechanical model for its functioning, but having limited knowledge in the field of biology, he was unsure about what structures in the brain would give rise to these properties. Stuart Hameroff, also deeply interested in cognitive neuroscience, was intrigued by the observation that general anesthetics were found to bind inside neural microtubules in the brain. Joining forces, Penrose and Hameroff started to build a model of consciousness stemming from quantum processes inside microtubules.
So, what are microtubules? They are long polymers of tubulin protein that are found inside every cell of your body. Generally they are responsible for maintaining cell shape, helping segregate chromosomes during cellular division, and function as highways for motor proteins that transport materials throughout a cell. Microtubules are highly dynamic, meaning that they are constantly elongating and shrinking depending on the job at hand; however, in neurons, microtubules form incredibly intricate lattices that stretch from the dendrites all the way down the axon to the terminus of the cell. Given that neurons rarely (if ever) undergo cellular division, these microtubule lattices remain quite constant throughout the life of an organism.
If we shrink ourselves down to the size of these microtubules and look at the specific proteins from which they’re assembled, the first thing you’ll likely notice is that they arrange in such a way as to form a hollow tube. If you were to take out your trusty magnifying glass and peer down this tube, you’d be able to observe arrays of aromatic amino acids (phenylalanine, tyrosine, and my favourite, tryptophan) that line the walls inside. The keen observer would note that these small molecules orient themselves in such a way that their flat, electron-rich, surfaces stack almost perfectly on top of one another’s. Throwing away your magnifying glass and taking out your quantum microscope – assuming you live in a futuristic society -, you might just notice something very bizarre happening; every now and then, to the keen observer, the stacks might shift slightly before reforming their original conformation. According to Penrose and Hameroff’s theory of Orchestrated-Objective Reduction, what you may have just seen is a quantum computation taking place between entangled electrons (synchronization of properties) of the stacked molecules. They postulate that quantum vibrations or the wave-like properties (similar to what was discussed in my previous blog post) of microtubules in neuronal lattices allow for synchronized quantum calculations to take place. According to Penrose, these computations occur as a direct resultant of the fundamental geometry of our universe; this means, according to their model, microtubules in any living entity can essentially read information (proto-consciousness) that’s ingrained in the fabric of our reality and systematically organize that information in neural circuits to generate consciousness). Wow.
So, how far out is this theory? Well, as it turns out, based on current research by Dr. Bandyopadhyay’s group at MIT, not very. They were able to detect quantum vibrations in microtubules at physiological temperature predicted by Orch-OR. Not only were these vibrations characteristic of the proposed model, they were also characteristic of another long observed phenomenon: brain waves. Electroencephalography (EEG) is used to measure activity in an active brain, and is observed as waves of electrical output. It has long been shown that different frequency waves are characteristic of different states of consciousness (sleep, anxiety, anger, happiness, intense thought etc.); however, the mechanism of their generation is unknown. The really intriguing observation that Bandyopadhyay’s group documented is that the vibrational frequencies of microtubules match the brain waves characteristic of an EEG output; I for one, don’t believe in coincidence.
Penrose and Hameroff go beyond proposing an actual mechanism for the accumulation of consciousness, and also comment extensively on the ability for information to be encoded within the structure of a microtubule. There is a known enzyme in the human body called calcium calmondulinkinase that’s responsible for the phosphorylation of tubulin (the protein that makes up microtubules). As phosphorylation generally results in a conformational change of a protein, they predict that different patterns of phosphorylation across the surface of a microtubule could allow for alteration of the specific interactions between aromatic amino acids within their cores. If this turns out to be true, then different phosphorylation states of tubulin could encode and store information in a similar way to how the computer you’re using encodes information by orientation of magnetic fields in its hardware; this gives rise to a mechanism for the storage of memories – currently a very poorly understood phenomenon. To lend credence to this, in Alzheimer’s disease, which is characterized by loss of memory, neural microtubules have been observed to undergo systematic deconstruction; could this help explain the loss of memory?
In the two decades since its birth, Orch-OR as faced countless critics; however, during this time, the scientific foundation upon which it stands has only strengthened. With the discovery of quantum vibrations in microtubules, even the harshest of critics are beginning to acknowledge (at a painfully slow rate) that Penrose and Hameroff might just be onto something. Like I voiced in my first blog post, part of the beauty of science lies in the ability for a long standing paradigm to be shattered by new elegant experimentation or with the simplest observation; maybe the discovery of quantum vibrations in microtubules will be the nudge our understanding needs to make a leap towards answering the biggest of questions: why are we here?
A moderately-inspired science student.