Visual imagery without visual perception?

RESUMEN

The question regarding visual imagery and visual perception remain an openissue. Many studies have tried to understand if the two processes share thesame mechanisms or if they are independent, using different neuralsubstrates. Most research has been directed towards the need of activation ofprimary visual areas during imagery. Here we review some of the worksproviding evidence for both claims. It seems that studying visual imagery inblind subjects can be used as a way of answering some of those questions,namely if it is possible to have visual imagery without visual perception.We present results from the work of our group using visual activation indreams and its relation with EEG’s spectral components, showing thatcongenitally blind have visual contents in their dreams and are able to drawthem; furthermore their Visual Activation Index is negatively correlated withEEG alpha power. This study supports the hypothesis that it is possible tohave visual imagery without visual experience