The neuroscience of consciousness and agency Flashcards
The two questions we are going to touch on?
1) how does the brain cause a mind?
2) how does a thought cause an action?
What is consciousness?
Do your thoughts cause your actions?
- You have a brain, you have a mind and somehow out of all of that emerges you.
- You have a point of view and that point of view experiences things.
- So when people talk about consciousness, one way that has been framed in terms of this idea of the easy problem and the hard problem.
The “easy problem”
- The easy problem of consciousness has something to do with access to information.
- For example, your visual system responds to electromagnetic radiation (light in the environment). Based on this it assembles a sort of simulation of what the world is out there. If you look out into the world, you can see that all these things are moving, there are people and you can use this information to guide your behaviour.
- You use the fact that you can see the world to interact with the world more effectively, to guide your actions.
- You can used stored memories to guide your behaviour.
- These different systems that enable us to extract information from the world, store that information, retrieve that infomation and use it to guide behaviour.
- Basically systems neuroscience - the different systems that make up the brain and the nervous system.
- There is so much we do not know; how is this information is brought together, how are different parts of this system accessing different aspects of information.
- We call it the easy problem because we think we understand what the answers are going to involve - network, synapses, how the brain processes and transforms information.
What do we think consciousness is for?
To enable flexible behaviour in the face of changing circumstances.
* Without consciousness, we would just be automotons. We would just be responding to stimuli and eliciting responses. But, instead we can see that something is not working and try something else.
The spotlight of consciousness
- Inside your brain, you have this spotlight that can be directed towards different things and this enables flexible behaviour.
- Spotlight of attention can be directed to a new goal.
The “hard” problem
- What we call subjectivity.
- The fact that all of this feels like something. Being conscious is like something - you know it is like something because you are experiencing it right now.
- Many people think it is not solvable at all or it is not solvable by studying synapses, neuronal networks in the brain - it is not a neuroscience problem. Some people would disagree.
- Examples of hard problem: when you look up at the sky, you are not just detecting electromagnetic radiation, the sky actually looks blue. When you feel war, it is not just your body detecting temperature, it actually feels like something.
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Examples that exemplify why this is such a difficult problem?
1) Congenital insensitivity to pain: a very rare inherited disorder caused by a mutation in voltage gated sodium channel expressed in pain sensing neurons. Rare individuals that have two mutant copoes of that channel and both copies lead to non functional channels. These people experience no pain whatsoever. Imagine trying to explain to one of these people what the feeling of pain feels like… it is impossible. If you have never experienced pain in your life, it is impossible to understand it.
**What we mean by subjectivity is that the only way you can understand the experience is to have the experience yourself. **
2) Describing red in terms of neurons in the brain is never going to make sense. You can find all the neurons in the brain that are responding to the color red but this still doesn’t explain what read is to you or what it subjectively looks like.
What is it like to be a bat? Thomas Nagel
- What is it like to see with your ears? you can only know what it is like if you are a bat.
- The only way you can know how it feels to see with your ears is to be able to see with your ears…
- You can’t know what it is like to be a bat unless you are a bad.
- You can’t know what it is like to experience pain unless you actually experience pain.
Studying the neural correlates of consciousness
- Studying the neural correlates of consciousness - what is the brain activity that happens when you have conscious experiences. There are two sort of divisions of that:
1) What is happening in the brain when you have a specific kind of experience.
2) What parts of the brain are active when you are conscious versus when you are unconscious (anesthesia). But this still does not get to the question of how that activity actually causes you to see the color red or feel pain or have any conscious experience.
How does consciousness “cause” voluntary action?
Your sense of self (sense of what you are) is crucially dependent on the idea that you get to decide what you do.
* You are able to consciously make decisions. But how does that work? We can call this conscious will or agency, or free will.
* There is all this neuronal activity going on in your brain and you have this feeling that your conscious thoughts are actually causing your actions. BUT, it seems like it should be the other way around… APs, sodium channels oppening should cause consciousness. **How can a conscious thought cause a sodium channel to open? **
Readiness potential
- The readiness potential precedes voluntary movements.
- When people are asked to make voluntary movements and then when experimenters are recording EEG in the SMA/pre-SMA, there is this activity that occurs before the movement and the activity sort of builds up for about one second before the voluntary movement and then drops back down when the movement is actually made.
Benjamin Libet Experiments
The readiness potential precedes voluntary movements but when does the person become consciously aware that they have decided to move?
Experimental design:
* They are recording SMA and pre-SMA, the regions that would be likely to be involved in sort of high level aspects of conscious movement control.
* Had subjects hooked up to a device where they could detect movement in their arm and EEG to measure readiness potential.
* Sit there and whenever you feel like it, lift your arm up. The participant had to make a mental note of the time when they got the feeling of “I am going to lift my arm”.
* So they have a measure of when the arm moves, when the readiness potential started and a subjective measure from the subjects of when they became consciously aware that they were going to move.
* Our intuition tells us that the first step in this process should be the thought, then followed by some sort of activity.
* What they found: the readiness potential is building up and building up. The feeling that the subjects had they were consciously going to move happened before the movement but after the readiness potential had already started building up. The feeling of conscious will precedes voluntary movements but follows the beginning of the readiness potential by about 500 msec.
* This implies that the brain had decided to move before the person became consciously aware that the brain had made the decision.
* However, there is a lot of room for something else to be happening here, for it to have been misinterpreted.
Unconscious determinants of free decisions in the human brai.n
Chun Siong Soon, Marcel Brass, Hans-Jochen Heinze & John-Dylan
Haynes (2008) Nature Neuroscience, 1 1:543-545.Nature
Neuroscience , 11:543-545 (2008)
- This basic finding has been repeated many times: another paper in nature neuroscience in 2008. These guys not only recorded readiness potential but also did fMRI (more precise measure of brain activity).
- Detected when the subjects had the conscious thought - they had to say what letter passed on the screen.
- Found the activity is in the very front parts of the brain. They found activity in the most anterior regions of the brain that could precede that feeling of consciousness by up to several seconds.
- your brain has decided to change the channel before you have decided to change it. **The feeling of deciding to act is the result of brain activity that’s already been initiated. ** The movement is already going to take place by the time you have decided to make the action.
Why do we feel that our thoughts cause our actions?
The reason that we feel that a thought causes an action is it meets 3 criteria:
* Priority: The thought precedes the action. We think something and then it happens.
* **Consistency: **The thought is consistent with the action.
* Exclusivity: There are no other potential causes. There is no other explanation.
“We develop the sense that [our conscious] intentions have causal force even though they are actually just previews of what we may do.” – Daniel Wegner
Daniel Wegner model
- It feels to us like we have a thought that causes the action.
BUT, according to his argument what is really happening is:
* According to Wegner, it is not that this does not involve enormously complex network of cognitive systems interacting with each other, it is just that most of that processing is going on outside of consciousness.
* Its all this stuff that is happening inside our brain and we think that our brain is our conscious brain but there’s all this stuff that is happening underneath the surface.
* He is saying that leads to two paths: One is a path that leads to the action. The unconscious processing leads to action and it also leads to unconscious causes and conscious causes of the thoughts. So there is all this brain activity, it generates an action and a thought thats consistent with the action. So as a result, we come to think that the thought causes the action.
