I remember listening to the Reith Lectures in 2003 (available to listen again on the BBC website, including full transcripts) and being fascinated by them, so I was really looking forward to hearing V.S. Ramachandran give this discourse on neuroscience last night.
Amputees very often exhibit phantom limb pain, which can often be linked to an inability to “move” the phantom limb – i.e. it is paralysed – and then cramp pains result. V S Ramachandran has shown that mirror therapy can help in the treatment of this. A mirror is placed so that the patient with, for example, a forearm missing, sees a mirror image of the whole limb in the relevant position; on moving the whole limb, e.g. flexing the digits, the mirror image is seen to move and the patient experiences a feeling of movement in the phantom limb. Controlled studies have shown that if this is done over a period of time the phantom pain can be relieved, and in some cases the phantom limb disappears entirely. The treatment also has been shown to alleviate Complex Regional Pain Syndrome and paralysis due to stroke. In bilateral amputees similar results have been produced using virtual reality, but not as effectively.
What is very interesting is that if a phantom limb subject is touched on the cheek, it may feel as if a particular part of the phantom limb is being touched, so touching one point will be perceived as as touch on a finger, touching another the palm of the hand. If hot or cold water is dripped on this point it feels as if heat or coldness is being applied to the phantom limb; if water is trickled on the area and the subject “raises” their phantom limb, it feels as though the water is running uphill. It’s possible to map out the limb on the face. Professor Ramachandran explained that this is probably due to the area of the brain responsible for movement and motor information having anatomical divisions mapped onto it, with body parts which are separate being mapped adjacent to each other, and messages then shifting to the wrong receptors after an amputation – the mirror therapy shifts the messages again.
Another neurological disorder, apotemnophilia, has an otherwise rational individual wanting a perfectly healthy limb amputated – the very presence of the limb, which the subject can think of as gross and swollen, can cause great distress. Prof. Ramachandran has shown that using prisms and lenses to make the limb appear to shrink can remove this desire, but only for the duration of the apparent shrinking – unfortunately, as soon as the lenses are removed, the situation reverts.
Synesthesia was discussed next, in colour-graphemic synesthesia the perception of numbers being coloured was shown to be due to cross-wiring between specialised brain maps. Usually individuals perceive a number line as a straight line, but in number form synesthesia the line can be contorted and wiggly and it is thought that this is due to crossover between numerical and spatial cognition.
Prof. Ramachandran considers that synesthesia may be due to the brain having to add language processing onto existing brain systems in very recent evolutionary time. Although in modern languages words have arbitrary sounds relative to the object, he demonstrated that there is something to do with sound processing deep in the brain that transcends language, by describing two objects, one hard and spiky, the other soft and round; one is called booboo and the other keekee – the entire audience allocated the name booboo to the soft object. This is a well-known demonstration, but it’s still interesting to see it nonetheless.
Lastly the mirror neuron system was discussed. Mirror neurons are neurons that fire when an animal either performs an act or observes another animal performing that act. They have only been observed functioning in monkeys, but are thought to be present in other mammals (including humans) and some birds (particularly ravens). Prof. Ramachandran sees mirror neurons and their implication in imitative learning as the driving force in the emergence of civilisation, culture and language.
Following the discourse there were some excellent questions from the audience, including a rather lengthy one from Jonathan Miller (who later answered another question about dyslexia as it was a bit off-topic). What most fascinates me is that new findings in neurobiology are answering some deep and long-standing existential philosophical questions, and also that in his delivery the speaker was regularly making the audience laugh; his speaking style is so entertaining that I am hoping for big things from the book – which I’ve already bought: Phantoms in the Brain: Human Nature and the Architecture of the Mind is on my ever-growing pile of books to read.
It often seems to be compared with Oliver Sacks‘s The Man Who Mistook His Wife For a Hat, which does cover similar neurobiological disorders, but I found rather hard going – I didn’t find it particularly well-written, in fact, although I knew Sacks was English, my first thought was that it had been translated into English (not very well). It’s also more than a little dated, as well as out-of-date (originally published in 1985); I’m sure it’s a classic in its subject, but I was disappointed that I didn’t find myself much wiser about the reasons for the subjects’ behaviour when I had read the book (although I must admit to having stopped about two-thirds the way through as I found it was getting a bit repetitive too).