‘Nature in the form of man begins to recognise itself’
- Victor Weisskopf
Not strictly a conversation....this short essay tells the story of my experiences of a seminar called ‘How the Brain Works’ - Insights from complexity and self organisation’ at Imperial College on 21st September 2011. With thanks to Henrik Jenssen who cast his eyes over these notes.
The human brain looking back at itself - is how I thought of this seminar of mathematicians, neuroscientists and physicists on a humid mid September afternoon.
Each presenting scientist arrived with his kit bag of mathematical tools borrowed from other areas of science and maths to investigate and model what’s actually going on in the brain. This is part of the process - each brings his own approach, favouring this hammer or that wrench and maybe over time, after blunting and forcing one tool too many will refine his apparatus by some degree or create new ones.
The mathematicians began by looking at extreme oxygen highs or lows in the resting brain and observing brain waves, though we could only guess at what these oxygen levels signified. A neuroscientist used information theory and the idea of ‘surprise’ which is the difference between what we experience and what we expect. He proposed that we always try to minimise surprise, by changing our predictions or our sensations and that the brain is a Bayesian machine. Another neuroscientist saw the brain as a network. Cutting across anatomical structures and binning a lot of information along the way, he mapped out and analysed these networks. He proposed that the brain optimises resource efficiency and minimises time and said more intelligent individuals seemed to have shorter pathways and I wondered about mine..... The only brain fully mapped in this way so far is the worm. Lastly, a computer scientist introduced another mathematical metaphor - coupled Kuramoto Oscillators and talked about how they tend to synchronise. However, if the topology is right and under certain circumstances, and if they phase lag each other by a particular amount then they can partition into different oscillating states. These systems have the potential to model some aspects of the rest state of the human brain and may be compatible with the wave idea the mathematicians observed at the start. There had been some success mapping these oscillator models to pigeon brains.
Brains looking at brains - it was fascinating, a marvellous phenomenon in itself. And all these people spoke slightly different languages according to experience and discipline, with sometimes subtle sounding differences carrying vastly different meanings and I wondered what each brain took away with him or her.
I reflected on my brain and the experiences and processing it had been working on throughout the day: travelling in on my bike through busy west London, enervated by motorists on phones and the volume of traffic, choosing what to have for lunch, trying to figure out a chart of the energy contribution density of all the photons in the universe with an astrophysicist over lunch, and making the little drawings of delegates when it lost the thread of the argument in this meeting. Sitting in the hot room, at some point, each of us probably reflected on the complex and emotional experiences of our own brains, suspecting how incredibly far these theories need to go before we begin to understand ourselves, and wondering about the question of what may be missing from our approach. More generally, I considered our physical laws and wondered if nature felt this same unease about our theories about her.
The human brain is pint sized and has tripled in volume over the last 7 million years (maybe due to better food....). It is 100 billion neurons – the processing centres – or grey matter. And 1014 synapses – myelin insulated axons or white matter. Plus Cerebro spinal fluid.
For brain waves, please visit: http://www.youtube.com/user/jlvincent
Seminar convener: Robin Carhart-Harris
Seminar presenters: Henrik Jeldtoft Jensen, Kim Christensen, Karl Friston, Ed Bullmore, Murray Shanahan, Roseli Wedemann