The Enigma of the Human Brain

“As long as our brain is a mystery, the universe, the reflection of the structure of the brain will also be a mystery.” — Santiago Ramón y Cajal

Nerve fibers are weaved through the architecture of our brain as shown here in a computer model made by “The Human Connectome Project” from the National Institute of Health.

The human brain is a vast and intricate web of our experiences, emotions, and characters, governed by the laws of physics and described extensively through our understanding of neuroscience and biochemistry. We have a decent grasp on how neurotransmitters are shot in between the synapses of our neurons, passing on small electrical signals between each other to form thoughts and memories. We know very well the properties of the main neurotransmitters endogenous to the brain in order to express certain emotions that govern our actions and thoughts such as serotonin and dopamine; the pleasure chemical. But what drives the neurochemistry and physics of our brain that gives rise to consciousness in the more evolved sector of our brain; the cerebral cortex?

Humans at their core are animals just like all other terrestrial life. Animals are not unlike algorithms in that they are relatively simple biological machines that are fundamentally deterministic, yet have stochastic elements thrown in there too. Algorithms are just instructions on how to perform and execute complex tasks. We evolved just as all other species did to fight for a spot in the evolutionary arena, yet we came out on top by miles. But why? The answer has to do with our source code, our brains, and the fact that we are fundamentally governed by neurochemical processes. Above all, our consciousness as humans is an enigma and at the same time, the core of our being, our actions, and our egos, generated by the of our brains. One of the most complex objects in the known universe is likely sitting in darkness inside your skull.

Homo Sapiens are thought to have evolved from genetic descendants in Eastern Africa somewhere in the span of 200,000 years ago. At the time Humans were supposedly emerging, we shared the savanna with around nine other species of the genus Homo. Today, there is just one. However, the field of Anthropology is in dispute over when humans actually emerged and gained dominance as an ape species.

Computer reconstruction of the oldest known anatomically human skull found in Morocco. Philipp Gunz, MPI EVA Leipzig.

from Morocco have rewritten our long-lasting paradigm and assumption that humans emerged in East Africa around 200,000 years ago. Paleoanthropologists made the remarkable discovery of a mandible belonging to an anatomically modern human dating back 300,000 years. This not only terminates the long-held belief that early humans were confined to East Africa before spreading across the globe, but also sheds new light on our ubiquitous nature as a species throughout the entire continent of Africa spanning back as far as 350,000 years in . This raises the question: what role did our brains have in this if any at all?

Graphic showing skull cavity size triple over millions of years of human evolution.

We know the volume of our brain and the density of neurons per cubic centimeter. We also know from archeological finds that other species of the genus Homo such as the Neanderthals, Homo Habilis, and Homo Erectus have similar to smaller sized brain cavities. Newly discovered species of humans such as Homo Denisova and , have also forced us to rewrite our ideas of how exactly our brains evolved the way they did.

We have an enormous skull compared to other Human species except for Neanderthals which had a similar to larger sized brain. This also raises the question of mental capacity and performance in the context of evolutionary competitiveness. Did humans outsmart “everyone” else? This seems to be the case considering how lonely we are being the only species on earth with the cognitive capabilities we have, including abstract thought, complex social and emotional relationships, and a highly evolved cerebral cortex that enables consciousness, the true mystery that has evaded neuroscience ever since we cracked open our skulls and took a peek at our biological software.

The most detailed MRI scan of a human brain ever created, taking over 100 hours to image. Source: B.L. EDLOW ET AL/BIORXIV.ORG 2019

The Enigma

Consciousness is a polarizing subject in contemporary neuroscience, with no widespread scientific consensus for the mechanism behind our own subjective experience; a bit curious considering the fact we have explored more about the surface of the moon and Earth’s ocean floor than the more highly evolved regions of the human brain.

This is not the result of non-imaginative or unintelligent neuroscientists.

Our minds are so complex and so amazing in their physical, biological, and chemical processes that we seldom give thought to the rapid processes occurring within which give rise to consciousness. This is mostly visual and auditory data to produce the incredible reconstruction of subjective reality we experience as humans.

The reality is that what’s occurring to produce a conscious experience is not well understood yet, but this is changing, and fast. The question revolves around the subject of what we really mean when we say consciousness. A hot topic of strenuous debate in philosophy and neuroscience is the idea of panpsychism — that there may be discrete elements of consciousness in typically unconscious objects such as trees or rocks, ; the most well known subatomic particle.

De Anima Mundi, the world soul, a precursor to panpsychism.

As a physicist in training, I hear that and spit up a bit but I’m also open-minded as any scientist should be. This is where physics and the brain collide; a truly unstoppable force of scientific inquiry meets a seemingly immovable academic object of debate. We must tread lightly as scientifically minded humans, looking closely at what the brain is telling us about the physics of what's going on at the subatomic level when consciousness is actively being generated in the brain.F This right now is not necessarily feasible but merits enough scientific interest that it should be studied rigorously. Current technologies let us peer into the brain as it actively produces what we experience as reality.

Source: National Institute of Biomedical Imaging and Bioengineering.

The video above gives a great insight into how our brains utilize physics and the vast amount of visual and auditory data we receive when we are awake and thinking.

The process of conscious experience requires a carefully orchestrated sequence of events to occur at speeds on the millisecond scale; pretty quickly. First, light waves from our environment of varying optical frequencies that we see as color hit the surface of our eye and get refracted by the biological lenses in our eyes, flipping the image of photons and passing through the center of the eye. The flipped image then hits your optical nerve at the back of your eye which is converted into electrical signals that pass through your optical nerve into your visual cortex. Your brain is presented with a vast amount of data and stimulation and must decide which to prioritize. It flips the image back upright so gravity makes sense in our visual field then prompts your body to react quickly and ensure an expedited package of coherent data that is somehow self-aware of its own conscious processes occurring… This gets messy. I am thinking about consciousness as I write about consciousness.

It then seems to be a self-recursive process of making sense of the world around us and deciding which stimuli require our awareness. The topic of consciousness continues to elude science by stonewalling us about the possible and tenable connection between physics and the brain, yet technology has advanced so much over the past ten years or so that we may be on the verge of cracking the enigma that is the human mind.

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Matthew Forman

Astroparticle physics PhD candidate at UC Irvine, Citizen Scientist, curious Homo Sapien. instagram: @human_wavefunction, twitter: @human_wavfnctn