Decreased lateral geniculate nucleus activation in retrogeniculate hemianopia demonstrated by functional magnetic resonance imaging at 4 Tesla.

Functional magnetic resonance imaging (fMRI) can detect lateral geniculate nucleus (LGN) activation. We studied LGN function in 5 patients with retrogeniculate homonymous hemianopia using fMRI at 4.0 Tesla during binocular visual stimulation. Decreased activation of visual cortex and LGN on the side of the lesion was observed in all 5 patients. These findings suggest that retrogeniculate lesions are associated with decreased activation of the LGN, due to retrograde degeneration or a functional decrease caused by decreased feedback from ipsilateral visual cortex.