:: Neuropsychology:Phantoms in the Brain, Vilayanur S. Ramachandran.

The history of mankind in the last three hundred years has been punctuated by major upheavals in human thought that we call scientific revolutions - upheavals that have profoundly affected the way in which we view ourselves and our place in the cosmos. First there was the Copernican revolution - the notion that far from being the centre of the universe, our planet is a mere speck of dust revolving around the sun. Then there was the Darwinian revolution culminating in the view that we are not angels but merely hairless apes, as Huxley once pointed out in this very room. And third there was Freud's discovery of the "unconscious" - the idea that even though we claim to be in charge of our destinies, most of our behaviour is governed by a cauldron of motives and emotions which we are barely conscious of. Your conscious life, in short, is nothing but an elaborate post-hoc rationalisation of things you really do for other reasons.

The human brain, it has been said, is the most complexly organised structure in the universe and to appreciate this you just have to look at some numbers. The brain is made up of one hundred billion nerve cells or "neurons" which is the basic structural and functional units of the nervous system. Each neuron makes something like a thousand to ten thousand contacts with other neurons and these points of contact are called synapses where exchange of information occurs. And based on this information, someone has calculated that the number of possible permutations and combinations of brain activity, in other words the numbers of brain states, exceeds the number of elementary particles in the known universe.


Now there are several ways of studying the brain but my approach is to look at people who have had some sort of damage to a small part of the brain, or some change in a small part of the brain, and interestingly when you look at these people who have had a small lesion in a specific part of the brain, what you see is not an across-the-board reduction in all their cognitive capacities, not a blunting of their mind. What you see is often a highly selective loss of one specific function with other functions being preserved intact, and this gives you some confidence in asserting that that part of the brain is somehow involved in mediating that function.

You are going to see many examples of this in my lectures but just to give you a flavour for this kind of research, I'm just going to mention two or three of my favourite examples.

One of my favourites is prosopognosia, or face blindness. When there is damage to a structure called the fusiform gyrus in the temporal lobes on both sides of the brain, what you get is a patient who can no longer recognise people's faces. Now the patient isn't blind because he can still read a book and he's not psychotic or obviously mentally disturbed but he can no longer recognise faces by looking at people. Now that syndrome is very well known but there is another syndrome that is quite rare and that's what we call the Capgras Syndrome, and I'll give you an example of this. A patient I saw not long ago who had been in a car accident, had sustained a head injury and was in a coma for about a couple of weeks. Then he came out of this coma and he was quite intact neurologically when I examined him. But he had one profound delusion - he would look at his mother and say "Doctor, this woman looks exactly like my mother but she isn't, she is an imposter". 

Ted talks, Lecture, Click to Play

Dr. Vilayanur S. Ramachandran.

Further reading, Information courtesy:My brain, http://www.bbc.co.uk/radio4/reith2003/, http://www.amazon.co.uk/Emerging-Mind-Reith-Lectures-2003/dp/1861973039 .