The phantom phenomenon
V S Ramachandran, the Director of the Centre for Brain and Cognition at the University of California, has in the past been described as the ”‘Marco Polo of neuroscience” and a man who has “done for the brain what Galileo did for the Cosmos”. His key approach involves studying brain abnormalities to reveal more about the workings of the brain as, he explained, a small change can result in a highly selective loss of function. Ramachandran argues that looking at the correlations between physical and functional deficits should help us to understand the brain, in the same way that it has helped us to understand the rest of the body.
Ramachandran was in our building to record a special lecture, part of the Exchanges at the Frontier series Wellcome Collection hosts in collaboration with the BBC World Service. Among other topics, he spoke of the research he is perhaps most known for: phantom limbs.
We heard about ‘Victor’, a patient who had lost his left arm forearm in an attempt to illegally cross the Mexican border. Like 98 per cent of amputees, Victor could vividly feel the presence of his absent arm. Two thirds of ‘phantom limb’ sufferers also experience intense pain, as if the limb is clenched and tight. Ramachandran discovered that this pain could be resolved in many patients by using a mirror to superimpose the reflection of the real limb onto the phantom location. He found that movement of the real limb can ‘trick’ the brain into relieving the tension from the phantom limb. This method has since been used to successfully remove pain and restore mobility in other conditions as well, such as reflexive dystrophy, and potentially even during the first few months of having a stroke – although this is still in early stages of research. Interestingly, Ramachandran said, the phenomenon is beyond the purely psychological – research has found that the physical swelling of painful limbs is also reduced following mirror treatment.
Mirror treatment may demonstrate a function of mirror neurons – frontal lobe cells that become activated both when the individual carries out motor tasks and when they see that task being carried out by someone else. The precise role of mirror neurons is yet unknown, and forms the basis of Ramachandran’s most recent work. According to Ramachandran, these neurons may have been the root of human culture, providing a system by which we could watch and learn new skills. Outlining what is known as a ‘shattered mirror theory of autism’, he theorised how mirror neuron deficits might also account for many of the defining features of autism, such as failing to engage with and understand others. However, it’s worth noting that the theory remains controversial, with a range of conflicting evidence.
Besides phantom limbs and autism, Ramachandran also discussed his ideas about synaesthesia and its prevalence in society. The condition sees that the stimulus of one sense can produce sensations in another, leading to ‘tasting words’ or ‘smelling sounds’ (for more, see our recent interview with a synesthete). It is thought to have a genetic basis, where excess connections in the brain are not completely pruned away in early development. This leaves accidental cross-wiring between particular adjacent regions – for example, between the areas recognising words and colour in the brain, leading to grapheme-colour synaesthesia. Ramachandran believes that the synaesthesia gene might have some ‘hidden agenda’ that can explain its prevalence among society, and has noted that the condition is eight times more common in artists, poets and other creative people. He suggests that the excess connections aid synesthete in linking seemingly unrelated concepts in creative ways, making them skilled in the creative arts.
All the topics Ramachandran touched on were truly fascinating, exploring conditions and treatments almost unimaginable to those of us who haven’t experienced them. The full lecture will be broadcast on the BBC World Service in November (watch the BBC’s website, where you can also listen to lectures from the previous two seasons) and is well worth listening to. With so many interesting ideas, it was clear how has earned his status as one of the world’s most influential scientists.
Emma James is a summer intern at the Wellcome Trust.
Find out more about Exchanges at the Frontier on the Wellcome Collection website.