Chapter 1: Understanding Consciousness

What is consciousness? A groundbreaking perspective on this phenomenon, presented by neuroscientist Michael Graziano, sheds light on its nature and potential for replication.

Everyday, we grapple with two conflicting beliefs about consciousness. We tend to think that:

1. If someone behaves unintelligently, such as after a head injury, they lose consciousness.
2. Individuals who are “locked in” and unable to communicate or move are still conscious.

These observations prompt us to reconsider what consciousness truly means. It transcends mere subjective awareness. Information like the time, day, or recent events enters our awareness through sentient perception. This involves experiencing sensations—sight, sound, taste, touch, and smell—as well as emotionally charged feelings like disgust or pain. Distinguishing between perceptions and hallucinations is crucial; visions may feel real but do not guide effective action.

The brain's role in perception is to transform sensory data into meaningful insights. While awake, this process is highly integrated and automatic, fostering a sense of embodied selfhood. Our understanding of bodily states—whether our heart is racing or if a light on the wall is due to a breeze—contributes to establishing our sense of self and awareness.

In cases of vegetative states following brain injuries, fundamental functions continue to operate, yet the brain's capacity for “meaning”-making is impaired. Remarkably, if vegetative patients can respond affirmatively to questions after appearing unconscious, it indicates that awareness may persist despite the loss of wakefulness.

The same applies to locked-in patients. Their control over bodily functions may be severely compromised, yet they can still regulate their awareness. This distinction is vital as it offers insight into the essence of consciousness itself. What differentiates the experience of vivid subjectivity from mere perception is the integration of experience with self-awareness.

A pivotal brain region known as the claustrum is thought to be integral to subjective awareness due to its rapid information integration capabilities, linking various areas of the brain involved in conscious sensory experiences. If we could monitor the claustrum's activity in individuals with permanent brain damage both in unconscious and conscious states and found no significant differences, we might conclude that subjective awareness is a byproduct of typical brain activity.

Conversely, if detectable differences exist in brain activity between unconscious and conscious states, it would suggest that awareness is distinct from mere information processing. This would lead us to consider consciousness as an emergent quality arising from neuronal activity. If perception can occur without awareness, then why should consciousness not follow a similar pattern?

The claustrum, located above the cerebrum, is unique in that it is not part of the cerebrum or cerebellum—the brain's motor and cognitive centers. Although it lacks its own blood supply, it connects with both regions, playing a crucial role in integrating information and driving the default mode network, which is notably active when we are awake and at rest. Damage to the claustrum may leave patients awake, yet unable to respond actively to stimuli.

Interestingly, stimulating the claustrum with magnetic pulses can evoke conscious experiences. For instance, an anesthetist might stimulate the claustrum of a locked-in syndrome patient to assess consciousness, leading to reports of sudden awareness. However, this raises questions about the authenticity of such experiences; it may simply be a simulated perception of consciousness rather than actual consciousness.

I propose that the claustrum acts as a switch in this network, modulating activity levels. In a comatose state, the switch remains inactive, whereas conscious awareness involves varying levels of activity.

Chapter 2: Consciousness Across Species

Can animal studies provide insights into consciousness? Does our understanding of human consciousness extend to animals?

The theory of consciousness I have outlined relies on a somewhat arbitrary division between conscious and non-conscious states, assigning consciousness based on behavioral responses. It does not address the mechanisms underlying consciousness or why one is conscious in certain states and not in others, such as during general anesthesia.

Is consciousness in animals linked to their intelligence? Are dogs more conscious than goldfish? What about cows? Since consciousness is not exclusive to humans, we might ponder: what differentiates human consciousness from that of other animals? For instance, why does an orangutan exhibit a form of consciousness distinct from that of a chimpanzee or gorilla?

In terms of DNA, humans, great apes, and gorillas share 98% similarity, with a unique 4% in humans believed to underpin our distinctive conscious experience. What unique exchanges does consciousness afford us that animals lack? While our pets perceive the world similarly, our understanding of their experiences remains limited. We cannot fully empathize with their pain or thoughts, nor can we grasp their motives. Yet, we still cherish and care for them.

Research on animal consciousness is groundbreaking and may one day unveil fundamental truths. However, such studies may not fully illuminate the complexities of our own consciousness or the minds surrounding us.

In our quest for understanding, we often turn inward. We seek reflections of our subjective experience in the external world, yet find little to mirror our internal consciousness. Perhaps there exists a higher consciousness in the universe, waiting to be discovered, which could offer deeper insights into our own consciousness.