Imaging interhemispheric interactions in normal and monocularly deprived young visual cortex by manganese-enhanced magnetic resonance imaging

Abstract

This study employed in vivo high resolution manganese-enhanced magnetic resonance imaging (MEMRI) to investigate interhemispheric interactions in normal and monocularly deprived visual cortex of rats with unimpaired vision, left or right eyelid suturing, or left or right eye enucleation. After seven days with altered vision, the animals were injected with manganese ions into the right visual cortex and imaged with an inversion-recovery modified driven-equilibrium Fourier transform sequence. The results showed prominent manganese transport, via the splenium of the corpus callosum, to the left hemisphere where the signal enhancement peaked on the border of the primary/secondary visual cortex and expanded medial-laterally with layer specificity. Significant decrease of transcallosal manganese labeling of the left hemisphere was observed after left eyelid suturing, left eye enucleation, and right eyelid suturing but not right eye enucleation, suggesting that the adult brain recruits different mechanisms for adaptation under different circumstances. Our findings demonstrated MEMRI as an efficient tool for investigating interhemispheric interactions both anatomically and functionally.