The neural correlates of consciousness

[ Jingle ] In this video, we’ll explore the idea that your conscious experiences can be identified with particular states of your brain. Ever wondered why eating, drinking, playing sports, listening to music or having sex makes you feel good? One explanation you may have heard is that all of these activities make your brain release a chemical called dopamine. Neuroscientists have found that increased dopamine levels are closely associated with the experience of pleasure. Of course, the actual science of dopamine and pleasure is much more complicated. But for the sake of philosophy, we can do with a simplified example. Suppose that neuroscientists can identify the distinctive brain states and processes associated with the conscious experience of pleasure. In other words, they’ve identified the neural correlates of a type of conscious experience. Does that mean that a particular conscious experience is a particular state or event in your brain? What does neuroscience actually tell us about consciousness? Well, first let’s clarify what we mean by “consciousness”. Our focus is on what is called ‘phenomenal consciousness.’ Phenomenal consciousness concerns the way our experiences seem to us. Think about it like this. For conscious creatures, things always feel some way or another. In other words, there is something it is like to be a human being, a bat, a mouse, and so on. This aspect of our experience - the way it feels- is what we mean by ‘phenomenal consciousness’. By contrast, it doesn’t feel any particular way to be a phone, a piece of cheese, or a bacterium. These objects don’t have phenomenal consciousness. In addition to thinking about what it’s like to be a human in general, we can also think about what it’s like to have specific experiences, or to be in particular mental states. There is something it is like to see a sunset, to hear a trombone, to taste coffee, to crave a glass of wine and to experience the good feelings we mentioned earlier. These mental events all involve phenomenal consciousness. We aren’t trying to give a full definition of phenomenal consciousness here. In fact, it seems likely that phenomenal consciousness can’t really be defined. It is a bit like what jazz trumpeter Louis Armstrong said about jazz: “If you got to ask, you ain't never gonna get to know!” But now, at least, you have a better idea of what we’re talking about. So, what would it mean to say that an episode of phenomenal consciousness just is a certain neural process in the brain? When we say that two things are identical, what we really mean is that there’s just one thing after all. If you say that Superman and Clark Kent are identical, you mean that there’s just one person, who we can describe both as Superman and as Clark Kent. So if we identify a particular episode of phenomenal consciousness with a particular neural process, what we’re saying is that there’s really just one thing, which we can describe either in terms of what it’s like to taste an orange (say), or in terms of neurons and brain chemicals. Neurons and brain chemicals are things we can study scientifically. So this identification implies that we can, in principle, advance our understanding of phenomenal consciousness through neuroscience. There are two sides to any claim identifying two things. If Superman and Clark Kent are identical, that means both that whenever Superman is around, so is Clark Kent, and that whenever Clark Kent is around, so is Superman. As philosophers like to say, it means that the presence of Superman is both necessary and sufficient for the presence of Clark Kent. Similarly, if we identify a neural process with a conscious experience, we mean two things. First, we mean that the neural processis necessary for the conscious experience; That is, that you can’t have that conscious experience without the occurrence of that neural process. And second, we mean that it is sufficient for the conscious experience; That is, that whenever that neural process occurs, so does that conscious experience. So, does our current neuroscience enable us to make such an identification? No, at least not yet. When neuroscientists are searching for the neural states that are responsible for phenomenally conscious experiences, they aren’t actually looking for processes that are identical to conscious experiences. Instead, they are looking for what we can call ‘difference-makers’ for phenomenal consciousness. They want to see what distinctive neural states and processes are involved in conscious states of different types. It’s kind of like coming across a row of light switches, and trying to figure out which one controls which light. For example, neuroscientists have found that a certain area of the visual cortex called ‘MT+’ is associated with the visual experience of motion. This might suggest that activity in MT+ is necessary for the conscious experience of motion, just like you might find that a particular light only turns on when you flip a particular switch. But it’s not plausible that activity in MT+ is sufficient for that experience. Why not? Well, for one thing, we couldn’t generate the visual experience of motion simply by putting a slice of MT+ in a bottle and putting an electric current through it. Flipping a switch on the wall isn’t sufficient for turning on a light you also need a source of power, functional wiring, light bulbs that work, and so on. Similarly, having a particular experience requires much more than just activity in a particular part of the brain. So particular neural processes can’t really be identified with the conscious experience of motion. Instead, we should think of them as “difference makers” for such experience. Where does this leave us when it comes to a neuroscience of consciousness? Neuroscientists are making great strides in identifying the neural processes that make a difference to particular phenomenally conscious experiences. But this is just one piece of the puzzle. To identify phenomenally conscious experiences with certain neural processes in the brain, we need to identify the processes that are sufficient for such experiences. And there is a lot more work to do on this front. what do you think [ Jingle ]