22 June 2010

Homunculus demonstrated

A study by Matthew Longo and Patrick Haggard demonstrates how the body is not mapped uniformly in the brain. The hands, useful things that they are, are represented across a markedly larger cortical area than many other areas of the body (face, in particular the mouth, and genitals are also over-represented compared to other body parts).

Longo and Haggard put people's hands under a surface and then asked them to mark on the surface where the ends of their fingers and knuckles were. They found that people's representations of their hands is distorted by an underestimation of hand length and overestimation of its width. This distortion isn't uniform across the hands (less distortion for the thumb and index fingers than the others), which maps on to people's sensitivity across the hands. Interesting to consider why we should underestimate in one dimension and over-estimate in the other.

[via Not Exactly Rocket Science]

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