I have come across enough consciousness ideas that it merits its own page outside of Lessons from the Brain. The ideas below aren’t organized but are just a collection of ideas that I’ve come across.
The first idea that I’ve commonly encountered is that consciousness isn’t a uniform phenomenon but rather a collection of phenomena. People have often split consciousness into two/three concepts such as Anil Seth (consciousness level, content, self), Damasio (core, extended), Dehaene (global information, self-monitoring). This makes sense as like the term “life”, “consciousness” isn’t a single idea but rather a collection of ideas. I find the analogy between life and consciousness pleasing because it captures our current level of understanding. Life used to be mysterious and was thought to require spiritual or mystical elements, but after we dig deeper into biology, it isn’t a mystery anymore. While the definition of life is still debated (see this), it’s no longer as mysterious and intractable. I believe consciousness is at the same stage as life was, and that this will only change with time.
Another big idea in consciousness that I really like is Nagel’s Bat paper and how, fundamentally, the subjective nature of experience isn’t explainable by the objective nature of science. To paraphrase, “Subjective experience is by definition dependent on the viewer, but objective experience is by definition independent of the viewer.” This paper really comforted me because now I know that we can’t really explain the subjective experience of consciousness such as why I see red as “red”. Yes, I still believe that we can tease out the neural mechanisms behind seeing red, but never why it feels like something to see red.
As for the purpose/function of consciousness, I have no idea. My working hypothesis is that conscious is the “mastermind” of the brain. It tells the brain what to do but not how to do it. In other words, it initializes actions and processes, but never contributes to how they’re done. For example, we see this happening with the condition of “blindsight” where people are (somewhat) conscious of their surroundings even though they’re cortically blind. This relationship between blindsight and consciousness was explored really well in the sci-fi novel “Blindsight” by Peter Watts.
Speaking of that book, it has some great ideas about consciousness that’s grounded in neuroscience that I really need to revisit. Ideas such as how consciousness is like an xray telescope that was pointed at itself, how multiple personalities aren’t actually a disorder but a feature, how a superior version of the human race (called vampires) can see both versions of the Necker cube illusion at once, how life may have evolved without consciousness (the aliens), and more. There are so many interesting ideas in this book that I should really revisit someday.
Another important idea that I’ve encountered was in the textbook “The Neurology of Consciousness” at the last chapter. The idea is that suppose there are three areas in the brain devoted to, say, vision. One area takes in visual information from the eye, one generates visual information (implementing the ability to imagine/dream/simulate), and one compares the two inputs and generates our experience of vision. We’re only conscious of the last area as it generates our experience, but damage to any of the three areas affects vision. There are cases where patients show damage to one area that doesn’t affect the other. For example, some patients can’t imagine colors but can perceive and understand colors, while other patients can’t imagine or perceive colors, but still understand them. However, the interesting case is when a patient can’t understand colors. This would mean damage to the last area and is similar to species that don’t have that color in their visual spectrum. This is getting a bit long so you can read my textbook notes to learn more, but this idea makes so much sense to me. It also finally places an idea of where consciousness is and explains agnosia (unawareness of a deficit).
This “three area” hypothesis hints at the ideas that: not all parts of the brain are involved in consciousness, consciousness is fundamentally different from perception generated by external or internal signals, there are areas of the brain dedicated to consciousness, something special is happening in those areas that generate our experience of qualia. I need more time to explore this idea but it just seems so right because it explains the evidence/conditions that we see and explains how a species can develop a new sense. It first has to develop the sense organ and a corresponding brain area to process that sense. Then it adds on the ability to self-stimulate that area, thus implementing dreaming/simulation/prediction. And finally, these two outputs are routed to some area that compares them and consciously experiences them.
Another idea that I’ve been thinking about is that consciousness must lie somewhere along the sensory pathway. What I mean by this is say you follow a signal, say from the eye, along all paths. So first, the signal is created at the retina, then it’s processed by the retinal circuitry, then it goes to the brain. We know this entire pathway isn’t applicable to consciousness because destruction of it has no impact on consciousness, just conscious experience/content. Next, we follow the signal throughout the brain and at some point along this pathway, consciousness must be present because we consciously experience the visual stimulus. Evidence suggests that it isn’t in the visual cortex since it’s destruction also has no direct impact on consciousness. However, at some point along this pathway, damage to that specific part of the pathway results in agnosia and this means that part is responsible for our conscious experience. Evidence for this comes from the three conditions that we see with brain damage: people that are aware that they’re blind, people that are aware that they’re blind but not really (blindsight), people that aren’t aware that they’re blind (animal with no vision).
One more idea about consciousness is that I’m not sure whether it lives in the activity of the nervous system or the structure of it. My hypothesis is both because people that show no brain activity aren’t conscious, but from the Connectome book I read, the activity shapes the structure of the nervous system network, while the structure also affects the type of activity possible. In other words, structure and function are tightly linked but I’m leaning towards consciousness as the activity, with memory/thought possible as the structure. This idea isn’t super clear to me now but the outlines are there.
Anyways, these are some thoughts I have regarding consciousness. All of these ideas can be expanded upon but the crucial aspect is combining all of these ideas (and possibly other ideas) into a consciousness framework. This will take time and effort that either I or someone else will do. As we often find in science, if one person discovered an idea, someone else would’ve discovered it too (the adjacent possible).