One of my children experienced this when she was twenty. She caught bacterial pneumonia and subsequently developed sepsis. She was put into a drug-induced coma for two and half weeks while the fabulous NHS staff worked to save her life. We were briefed that when she was brought round, she would have no idea how long she had been unconscious. The doctors were right: she could not believe she had been in a coma for so long and found the whole experience disconcerting. I am delighted to say she has made a complete recovery. She was almost the same age as I was when I had malaria, but I was lucky I lost only a few minutes of my life, compared to the seventeen days my daughter has no memory of. If we had monitored her brainwaves during her coma, they would have been random. Our levels of consciousness vary depending upon all sorts of things, and even what we are doing, with each state yielding a different pattern. Conscious thought has a particular pattern, while subconscious processes have another. Characterizing these different brainwave patterns is an active area of research. One reason psychologists think that some species of some animals have consciousness is they also have brainwaves that are neither entirely random nor highly uniform. For example, in 2023 an international team of scientists described how tiny implants were used to monitor the brainwaves of three free-living octopuses. The brainwaves detected when learning new tasks were very similar to patterns seen in mammals, including humans, while other behaviours generated patterns that were like nothing seen before in any other animal. Research such as this across a wide range of animals reveals that some types of brainwave patterns are quite similar, even between distantly related species.
A few neuroscientists have gone so far as to state that consciousness is the brain’s electrical activity, although most don’t subscribe to this view. Electrical activity certainly provides the best approach we have for measuring how conscious someone, or something, is, but it does not provide an explanation for consciousness. The electrical pattern arises because of the way that brains work, and biologists, neuroscientists and psychologists are making great progress in revealing their inner workings. Some neuroscientists have argued that brainwave patterns in other species, including houseflies and shrimps, suggest that a degree of consciousness is widespread across animals, but we do not yet know what it feels like to be a housefly, Woofler or a bat.
The part of your brain where consciousness resides sits inside a dark box, your skull. It does not detect light, smells, sounds, touch or taste, but it turns electrical signals from cells in organs that do detect these things into experiences. The brain inside our skull receives signals from the eyes, ears, nose, mouth, skin, muscles and other organs as either chemical signals or electrical currents, and the brain then makes sense of these before sending chemical or electrical signals back to our muscles and other organs instructing them what to do. Some of these instructions are sent subconsciously, others following a decision having been made. All this can happen astonishingly quickly, if need be, but some decisions can take an age. Sonya can take minutes before deciding between the hazelnut noisette and the orange crunch in a box of Quality Street chocolates. She usually makes a mistake regardless of her choice, handing me a half-eaten chocolate, and much more quickly makes a second decision to eat the other variety to correct her initial error.
Your sense organs contain cells that can detect aspects of the external environment. Your retina, an organ at the back of your eye, contains nearly 97 million cells that can detect light of different colours and intensities. Each time particular proteins in the cells are hit by a photon they create an electrical charge, information that the brain can use. Similarly, cells in your nose contain proteins that attach to different molecules, allowing you to detect smells. When you cook bread the action of yeast in the dough produces chemicals called ethyl esters. Some cells in your nose have proteins that can bind to ethyl esters, and when they do, they send an electrical signal via the olfactory nerve to your brain. You then decide what to do, which in my case is to usually search the fridge for some butter. Your other sense organs operate in similar ways, but instead of detecting light or smelly molecules they instead detect sound, touch or texture before sending electrical signals to the brain.
The brain takes all these signals from the sense organs and builds a simulation of the world around you inside your skull. You might smell a freshly baked bread roll, locate it by looking around the kitchen, and determine it is still warm by touch. Your brain simulates an experience of finding a freshly baked bread roll and you then decide what you are going to do with this information.
The simulation of the world our brain creates may, or may not, be accurate, but it is sufficient for us to survive and hopefully thrive. There will be differences between the simulations that different people’s brains create. For example, my sense of greenness, or yellowness, or redness, may well be different from yours (this is the hard problem of consciousness again), but it matters little if we can both agree that an object is a particular colour. The important thing is that the simulation of the outside world we experience contains sufficient information for us to decide to take sensible actions. For most animals, these actions involve the detection, acquisition and utilization of resources such as food, water, a territory or a mate without succumbing to something that could kill them. In humans our actions go beyond this, as they might involve completing a crossword, taking the dog for a walk or deciding what colour to paint the bedroom.
Building a simulation of the world, and working out how to respond to it, is a complicated task. The human brain is the most complex object in the known universe. It is amazing, so look after it. Your brain is your body’s command centre, and its primary role is to keep you alive. Some of what our brains do happens without our knowledge. It moderates our body temperatures, manages our heart rate and controls many instinctive behaviours. These all happen in the subconscious, although with concentration we can take conscious control of some of these processes, such as our heart rate. As well as doing all this, our brains also store memories, and these play an important role when we decide how to act in a given situation.
The human brain is divided up into many separate parts, but at the crudest level it can be partitioned into three distinct areas: the brainstem, the cerebellum and the cerebrum. The brainstem is evolutionarily the oldest part of the brain and it regulates most of the subconscious processes that are required to stay alive. It keeps the heart pumping, the lungs breathing and many of our other organs functioning. It is found at the base of our skull by the top of the spinal cord. The second area is found towards the back of our skull and is called the cerebellum. It is the command centre for movement, and is how we voluntarily control our muscles. As I type this paragraph, it is the cerebellum that is directing my fingers where to go on the keyboard and when to press down as I type. The cerebellum is all about fine motor control, and if it were to be damaged my typing would become wonky. But that is not alclass="underline" this part of the brain also plays a role, along with another part of the brain, the amygdala, found in the cerebrum, in regulating our responses to fear and pleasure. The third area of the brain, the cerebrum, is the largest part and it is responsible for sensing smell, speech, thought, emotions and learning. The largest part of the cerebrum in humans is the neocortex, and this organ alone takes up over half the size of our brains. It is the neocortex that gives us our intelligence and likely our heightened sense of consciousness.