I read an interesting book, “Consciousness and the Brain” by Dehaene. It’s been on my stack for months and as I started reading it I thought, ‘oh I should have read this months ago’. But I am realising I can think that about almost every book so I’m just glad that I have now read it. The book is about what he calls, Conscious Access – we become aware of something.
Here are some of the highlights from it:
- The image at your eyes moves around a lot and all the blood vessels are in front of your rods and cones, so images are blurred, blotchy and moving, yet we don’t see any of that. It seems that this can be tracked through the lower visual processing areas. It is not until it gets to higher neural areas that it’s sorted out; therefore, we see a clear and stable picture of the world.
- Even if we are not conscious of it (eg. Famous gorilla and basketball experiment) the input goes a long way up into our brain. So, at any moment our brain is processing a lot of information that we never get to be aware (conscious) of. And some of it affects or biases our thinking.
- These inputs get weaker as they travel upwards but some trigger higher neural areas which then send a signal back down to the sensory input. From my understanding, this signal is checking out what it thinks could be happening. If the sensory input comes back as agreeing then the higher cortical area gets more excited. A reinforcing loop gets set up and gains strength.
- About 300ms after the initial stimulus the excitation gets strong enough that suddenly the cortex ‘ignites’, as he puts it, into lots of activity. It’s quite sudden and extreme.
- This activity is the higher cortex sharing that information all over itself with lots of long-range axons firing. This neural network sends signals back and forth in a way that creates an oscillation of electrical activity, in the Gamma band (33+ pulses per second), which can be monitored outside of the brain.
- The other thing that happens is that the active neurons tightly shut down (inhibit) other neurons so that your attention becomes very focussed. New sensory input will find it hard to trigger another neural circuit into activity, as at this time the brain deems that information to be irrelevant. In fact, the wave of activity is a positive voltage at the top of the head not a negative wave because there is more inhibition activity going on than excitory.
- It seems that when we get stressed, the neurochemicals that cause vigilance increase and therefore we are more vigilant. This means we respond to fainter stimuli – I think this shows up as people perceiving things as more threatening when they aren’t. (It could be that when we talk about how important relationship is in coaching, that what we are doing is reducing the amount of these neurochemicals being released.)
- It appears that in babies the wave of ignition happens but at about 1 second – probably due to the lack of myelination at this age.
- He talks about Schizophrenia and how a disruption in creating a connected, excited neural network could create similar symptoms. It seems the brain gets the bottom-up sensory information but the top-down check from the higher areas to the sensory areas is impaired. This is checking for “I think it is this, are you sensing that?”. If it gets a signal back which matches its expectation of what it thought then there is no mismatch between expected and sensory input and the brain is satisfied it ‘knows’ what’s going on. If this loop is disrupted then the neural circuit does not get closure so the person will be ‘left’ with a feeling that something isn’t quite right or is missing. As the brain doesn’t like discrepancies, it invents a story to make sense of it. Also, when we do something, that part of the brain alerts the sensory areas to expect it – that’s why we can’t tickle ourselves and when we hear ourselves echoed back in a phone call we get disorientated as we weren’t expecting that. Again, if this is impaired then the person would not always realise it was them doing it, hence the claim of ‘other voices in my head’.
- The brain is in a constant state of flux so these ignitions are happening without external stimuli. In fact, he reckons that the brain creates more of these ignitions internally or randomly than are externally triggered.
Dehaene, and others, are doing some amazing work with Comma, Vegetative-state, minimally conscious and Locked-In Syndrome patients. They are developing a test for consciousness in these patients. It seems that they have detected consciousness in Vegetative state patients who months later regain a further level of consciousness. Also in one very special 2007 case, a neuroscientist triggered a patient’s Thalamus area (electrodes) which is heavily involved in the system that determines how awake or vigilant we are. They thought this overall system might have been stuck in the ‘not awake’ mode and they managed to ‘kick-start’ it so the patient went from minimally conscious to a more stable state of consciousness. There are also some specific drugs which can bring back conscious to patients at the time they have them which points to the fact that if the system is not damaged then there could be a point in the future when we can awaken these people.
As a final snippet. I read (3 hours) a lovely book called, “The Little book of big stuff about the brain”: It is an easy and informative read about learning and reward, plus a bit on consciousness, and how to make those work well. Another book that took my eye, is called “Predictably Irrational”: looks like a thought-provoking business book although I haven’t read it yet.
Have a wonderful Christmas and I wish everyone the very best for 2018.