Figure 5.

Summary model. The correlation of spontaneous signals between cortical visual areas is influenced by both shared input signals and intrinsic neural activity. Blindness reduces shared, between-hemisphere input to visual areas, from both retinal and higher cortical sources. The signals intrinsic to hierarchical, connected visual areas therefore constitute a greater proportion of spontaneous neural activity, enhancing the relative strength of hierarchical correlation measures as compared to indirect. Congenital blindness has the additional effect of broadening between-visual-area axonal arborization and thus measured cortico-cortico receptive fields.