Full Idea
Scans show that a sub-section of the visual cortex called V5 - the area that registers movement - lights up during blindsight, even though V1 - the primary sensory area that is essential for normal sight - is not active.
Gist of Idea
In blindsight V1 (normal vision) is inactive, but V5 (movement) lights up
Source
Rita Carter (Mapping the Mind [1998], p.307)
Book Reference
Carter,Rita: 'Mapping the Mind' [Phoenix 2000], p.307
A Reaction
The whole point of blindsight is to make us realise that vision involves not one module, but a whole team of them. The inference is that V1 involves consciousness, but other areas of the visual cortex don't.