Does the key to consciousness lie within our brains?
Much recent research supports the view that science can describe consciousness
A greater understanding of consciousness carries the potential for bringing wide benefits, but also carries dangers. Photograph: iStock
In the first of a two-part series Seán Duke examines the science and philosophy of consciousness – starting with “the insiders”; those who believe answers are found inside the brain
Consciousness: the miraculous, mysterious process by which each of us thinks and is self-aware. Does it arise from inside the physical brain, or from something mysterious outside of it? Brain-scanning studies have convinced most that the answer lies inside our heads.
Consciousness has fascinated great thinkers since ancient times. In the fifth century BC, Socrates put forward the idea that the mind and body were made of different stuff. French philosopher René Descartes updated this for the Enlightenment age with his idea of dualism, which held that there was a mind independent of the body.
This metaphysical idea – that the mind is a mysterious entity that is somehow separate from us – remains influential to this day. The study of consciousness remained solidly in the philosophical realm up to recent times as science had no way to measure it. That changed in the early 2000s with the arrival of brain scanning machines such as functional magnetic resonance imaging (fMRI).
These powerful scanners enabled scientists, for the first time, to peer inside our heads and seek out the signs of consciousness. It is a common belief that humans are exceptional and superior to other animals, because we are conscious and self-aware.
However, a growing body of evidence now suggests that consciousness is shared across the animal kingdom, albeit at differing levels. Humans are certainly exceptional, however, in the unique ability to consciously reflect on experiences and to share these experiences with other members of our species through shared language.
But scientists remain unsure why consciousness first evolved, or what survival advantage it gave us and other animals. There is an idea that it provided us with an ability to respond to our environment, such as moving to greener pastures when required.
Higher consciousness took millions of years to evolve, so scientists believe it gave our human ancestors a big survival advantage. To study consciousness, it must first be defined. This can be difficult as there are many aspects to conscious experience.
There are the thoughts we have when waking in the morning and making plans for the day ahead. There is our emotional response to a piece of art, a book or poem that taps something deep in us.
Our conscious experiences are subjective, individual and private by nature and are notoriously difficult to capture, measure and study. There are neuro-chemical signatures in the brain that arise from some aspects of consciousness, such as our ability to pay attention.
Neuroscientists know that we tend to pay attention to the things in the environment we are interested in, and this can be measured. Another important aspect to consciousness is memory, as we spend time reflecting on the past and how it relates to the present. The brain activity that results from memories can also be measured.
Despite this some philosophers, including David Chalmers, professor of philosophy and neural science at New York University, still believe science is unsuited to the study of consciousness. Science doesn’t know what consciousness is, the argument goes, so it doesn’t know what is looking for, and can’t get access to it let alone measure it.
There are others, such as Daniel Dennett, professor of philosophy at Tufts University who counter that since consciousness is the by-product of a working brain, that it is well within the grasp of science and scientists to study, describe and understand it.
Dennett has been studying consciousness since the late 1960s and is considered one to be one of the leading authorities on the subject. “There’s a lot of people who really don’t want consciousness explained; they want it to stay mysterious,” he says. “Consciousness is not just one thing. It’s a whole host of different features, which gradually have emerged.”
“The consciousness of a snail is minuscule compared to the consciousness of a monkey or a bird, which is minuscule [compared with] our consciousness,” Dennett adds.
The idea that consciousness evolved slowly from single-celled organisms is one that appeals to Kevin Mitchell, associate professor of genetics and neuroscience at Trinity College Dublin and the author of Innate: How the Wiring of the Brain Shapes Who We Are.
“Let’s say we have unicellular organisms, like bacteria, or amoeba, and then they evolved multicellularity.” Mitchell says. “Well, what does that give them that they didn’t have before it gets them a division of labour, for example?” “And then we have the invention of a nervous system: what does that do for the organism in terms of letting it know what’s out in the world, letting it interpret things?”
His answer is consciousness – ever-increasing levels of it provide species that have it with clear survival advantages. Neither is consciousness mysterious, says Mitchell, or metaphysical, but something that naturally emerges from the brain’s structure.
There has been much research over the past few decades that supports the view that science can describe consciousness. For example, neuroscientists know that looking at certain colours, such as red, influences brain activity, which can be read in a scanner.
There has been research done, too, on more complex inputs into the brain, notably language. Scientists are investigating not just what happens inside the brain when people hear language, but how brain activity differs when words are randomly put together, as opposed to in a linked sequence that produces a meaningful sentence.
Lorina Naci, assistant professor at TCD Institute of Neuroscience, has studied consciousness levels in patients that are in a nonresponsive or vegetative state due to brain injury. “We are measuring neuro-chemical signatures of the brain activity in relation to conscious experiences,” she says.
“We have perception, we can hear sounds and we can see images and they get processed in a sensory-specific part of our cortex. What is happening in the brain is like millions of combinations of different types of parcels of stimuli and computations and bits of thought.”
For Naci, a greater understanding of consciousness is important because it can improve the lives of people with brain injuries. It makes sense in this context to attempt to decode what brain activity in each patient is associated with the words “yes” and “no”.
Brain activity is monitored in patients inside scanning machines as they are asked questions with yes or no answers, such as: are you married; do you have children? This means the brain activity associated with yes and no for that person can be pinned down and used to facilitate communication.
This research is of potential benefit to a large group of patients. In the US alone, 50,000-100,000 people per year end up in a vegetative state and don’t seem to be meaningfully conscious. Yet perhaps one in five people in a vegetative state have a sophisticated level of conscious awareness.
Their families are keen to know whether they can hear anything, understand language, or if they have a functioning memory. The findings can be remarkable. One person whom Naci says was in a vegetative state for 12 years was found to be consciously aware. It is a comfort to families to learn that their loved one is conscious, and it changes how they, and medical staff, interact with them.
They can hear, they can understand language, and they can pay attention over time and respond emotionally. They feel suspense and follow the plot of dramatic films in the same way the rest of us do, she notes.
Naci is developing a portable technology that can be brought to a patient’s bedside to test out their consciousness levels. The unit works by measuring the tiny sweat fluctuations of the patient’s index and middle fingers, which indicates a response to being shown emotional content, such as a suspenseful film.
If the patient can follow the movie’s narrative, then by implication they can follow what a nurse or doctor says about their family. Naci’s research work is also important for those people who are “nonresponsive” because of advanced dementia or locked-in syndrome.
She is working with Colin Doherty, consultant neurologist, to get ethical approval for consciousness research at St James’s Hospital. One of the big things they would like to know more about is what the prognosis is for individuals in a vegetative state. There is little knowledge about what signs need to be watched for in people in a coma and what those might mean for their future.
It’s early days, but neuroscientists such as Naci can already interpret quite a lot of conscious activity that’s going in in people’s minds. She believes consciousness is the product of a functioning physical brain, but that some aspects of it remain mysterious.
It is unlikely, she says, that neuroscience will be able to understand every nuance of consciousness going on in a person’s brain. Yet, that is not the goal of scientists in this field, she says, but rather to focus on understanding those aspects of consciousness to improve the quality of life of people in nonresponsive states.
Like much science, a greater understanding of consciousness carries the potential for bringing wide benefits, but also carries dangers. Naci is sceptical about whether self-aware, conscious, artificially intelligent systems are possible in the future, but urges caution.
“We are already at the point where we need to take precautions and have opinions on the ethical use of AI [artificial intelligence] and what we are actually creating,” Naci says.
“As we create more complex systems, they might not have consciousness, but they will have a lot of power to influence human life.”
Part 2: The Outsiders – those, including Roger Penrose, who believe consciousness comes from outside the brain – will appear on April 1st