Are we humans simply remodelled apes? Chimps with a tweak? Is the difference between our genomes so minuscule it justifies the argument that our cognition and behaviour must also differ from chimps by barely a whisker? If “chimps are us” should we grant them human rights? Or is this one of the biggest fallacies in the study of evolution? NOT A CHIMP argues that these similarities have been grossly over-exaggerated - we should keep chimps at arm’s length. Are humans cognitively unique after all?
Wednesday, 27 May 2009
Mirror Neuron Theory Under Fire
I deal with mirror neurons in my chapter Inside The Brain, and slid in a short mention that not everyone in the world of neuroscience is a firm believer that mirror neurons exist and are the fundamental plank of much social cognition. Here New Scientist reports the work of Alfonso Caramazza, of Harvard University, who argues that neurons should adapt to repeated stimulation by reducing successive responses. If mirror neurons, which are said to fire both when you observe an action in the outside world and when you perform the similar action (a hand gesture for instance) for yourself, really do exist they should adapt therefore to both observation and performance - but they do not. He found only that they adapted when gestures were observed then enacted, but not the other way round. Mirror neuron afficionado Marco Iacoboni, however, is not impressed, claiming that mirror neurons are different to most classes of neurons in that they do not adapt. This would seem to be a space to watch. Mirror neuron skepticism is not going to go away.
Caramazza’s paper is seriously flawed. The technique of fMRI adaptation seemed very promising ten years ago, but careful studies on its neurophysiological correlates have demonstrated that its findings are uninterpretable. Indeed, Caramazza’s manuscript has been around for many years and nobody wanted to publish it. Caramazza managed to publish with an old trick that only PNAS allows: he handed it personally to a friend of his. The paper is basically unrefereed (this is what it means ‘Edited by...’ under its title).
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