At first glance, human consciousness seems like the one thing we should never have to doubt. We know we are conscious because we experience the world in vivid detail: the small luxury of a piece of chocolate; a song imbued with sadness; or a childhood memory that takes us back to another place and time. But for such a fundamental aspect of reality, what underlies consciousness — the experience of being aware of one’s own existence — has proved deceptively hard to pin down.
Researchers and philosophers have spent centuries debating how and why physical processes in the brain result in the subjective, first-person experiences we all seem to have. This issue, known as the ‘hard problem’ of consciousness, continues to drive research today. Scientists are still far from explaining how brain activity begets an entire inner world, but the field is making progress.
The advances that researchers have made include the ability to reliably measure brain activity and connectedness and probe for signs of hidden awareness. The emerging picture — based on insights from not just neuroscience, but also far-flung disciplines such as plant science, artificial intelligence and astrobiology — is not of consciousness as a single light that can be switched on, but as a coordinated condition that is potentially more widespread than previously thought. The rapid rise of AI, for example, has fuelled discussions over whether only humans can be conscious — and of whether a brain is even required for consciousness.
I’d argue we’re now in the thick of it, which is an exciting place to be.” There is no direct test for evaluating human consciousness, but researchers have made advances in establishing what are known as neural correlates of consciousness (NCCs). These criteria, which can be a single metric or a combination of events, identify the minimum neuronal mechanism required to kickstart a conscious experience. Specific neurons might need to fire, for example, and particular brain activity patterns could signify an internal experience.
Below these thresholds, a person might move through life not fully conscious of their behaviour — zoning out while driving, for instance, only to snap back to attention moments later. Some NCCs have been determined by studying people in states we don’t typically associate with consciousness, such as those who are asleep, anaesthetized or in a coma. According to Melanie Boly, a neurologist at the University of Wisconsin–Madison, this type of research is crucial to help separate true NCCs from activities that merely signify being awake and responsive to our surroundings.
Is social media changing children’s brains? Here’s what the science says Through that work, scientists know that about one-quarter of individuals who present as medically unconscious are, in fact, experiencing a type of covert consciousness in which they continue to perceive the world around them. In a landmark 2024 study, a subset of 241 people who had been left seemingly unresponsive by brain injuries were asked to imagine themselves engaging in activities such as playing tennis or opening and closing their hand.
Extract — continue reading at the source.
