Conifold Theory Basics, Part 1: Defining Consciousness

Consciousness is about perceiving the world, building an understanding of the world, and choosing our actions in the world. And these key features can be explained as natural emergent properties of neural computation.

Consciousness is not a well-defined word. But it is worth trying to define it. We can say that consciousness is about perceiving the world, building an understanding of the world, and choosing our actions in the world.

Many people believe that consciousness pervades the universe – that everything has some amount of consciousness or plugs into some universal consciousness. But neuroscience says there is something special about the brain that produces consciousness. Neuroscience says that perceptual experience and decision-making are tied to the activity of neurons in the cerebral cortex.

Neuroscience says that perceptual experience and decision-making are tied to the activity of neurons in the cerebral cortex.

In this view, rocks, thermostats, planets, laptop computers, and other inanimate objects are simply not conscious. And not every neural circuit produces consciousness either. To understand more about what consciousness is, we can compare two types of neural circuits in our own bodies – one that does not produce those two key features of consciousness, and one that does.

Spinal reflex circuits do not generate perceptual content or volitional action

Our spinal reflex circuits are very effective at collecting sensory data and directing motor output. If we touch a hot stove, the heat activates pain and temperature receptors in the skin. That sensory neuron is activated, and it sends a signal directly to an interneuron within the spinal cord. That interneuron then sends a signal to an alpha motor neuron, which activates flexor muscles to withdraw the limb. That simple three-neuron circuit quickly and effectively achieves the goal of keeping us safe from harm.

But when the spinal reflex circuit is activated, there is no perceptual experience of the sensory stimulus. It’s only a second or two later, when the nerve impulses have made their way to the brain, that we start to feel that pain. And when the spinal reflex circuit is activated, there is no decision to move the arm away from the stove. It’s a purely reflexive behavior, which is not prompted by volitional control and cannot be overridden by volitional control (unless the stimulus is expected and we prepare a response).

The fact is, we have unconscious neural circuitry without our own bodies. It is perfectly possible to collect sensory data and direct motor output without consciousness. We do it all the time! But we also have perceptual experience and the ability to decide our own actions. And these two critical features of consciousness are paired with neural activity in the cerebral cortex.

Cortical neural circuitry does generate perceptual content and volitional action

When we talk about consciousness, we talk about perceiving the world and choosing our actions in the world. We collect sensory data from our surrounding environment, but we don't just process this information - we experience the colors and sounds and smells. And we don't just send nerve impulses to direct the movement of our limbs, we organize a cohesive behavior and drive that movement to meet our goals.

There must be something unique about the way a sensory stimulus is encoded in neurons of the brain, because this encoding process generates perceptual experience and allows us to initiate volitional movement. This computational process must be categorically different from the way a sensory stimulus is encoded in the spinal cord, since these neural circuits do not generate perceptual experience and only allow for purely reflexive behavior.

Neuroscience must now explain what that difference is – what kind of neural computation generates qualitative perceptual content and volitional behavior, and what anatomical and physiological properties differentiate that process from neural computation in spinal reflex circuits.