I watched the whole BBC report and find every part fascinating, but one of the questions that intrigues me most is how exactly a person's inner world comes to be. Can we prove that the firing of neurons alone can create a person's consciousness?
Marcus de Sautoy seeks the answers from Professor Koch. Through advances in brain surgery, Koch has looked deep inside a living brain and has seen what happens when a conscious patient sees different images. Today, experimenters have the technology to detect the unthinkably small electric signals from individual nerve cells. The signals can be amplified, visualized, even heard over audio speakers. Experimenters have found that the brain has specialized neurons that give specific responses only to very specific, familiar images/individuals. This is not to say that only a single neuron fires for each familiar image. Many neurons respond, but the question of how many is another that remains unanswered yet.
In one of the experiments that give us this evidence, certain neurons in a person's brain responded to Halle Berry. These neurons gave the same strong response not only to all different photos of the actress but also to the text, "Halle Berry." Since the text bears no visual resemblance to any of the images, this proves that the neurons represent the concept of Halle Berry. Scientists thus call them "concept neurons." Recognizing concepts in this way is a capability of human brains alone. Neither animals nor modern computers could relate the photos of a certain woman to the text of her name.
This recognition of concepts is key to human consciousness, which, we have seen, comes into being through the firing of individual neurons. Koch makes clear that the many neurons together are what make consciousness. Like the wetness of water emerging from the vast collection of water molecules, consciousness emerges out of a collection of neurons. A single neuron isn't itself conscious, just as a single water molecule isn't itself wet.
This 2008 article from Science Daily provides more information about the experiments done that give evidence that single neurons are involved in consciousness.