Macromolecular tissue volume mapping of lateral geniculate nucleus subdivisions in living human brains

The human lateral geniculate nucleus (LGN) is composed mainly of the magnocellular and parvocellular subdivisions. The non-invasive identification of these subdivisions is, however, difficult due to the small size of the LGN. Here we propose a method to identify these subdivisions by combining two structural MR measures: high-resolution proton-density weighted images and macromolecular tissue volume maps. We collected MRI data from 15 healthy subjects and found that the spatial organization of these subdivisions identified by our method was consistent with post-mortem histological data. Furthermore, the stimulus selectivity in these regions measured by functional MRI was consistent with physiological studies. These results suggest that macromolecular tissue volume mapping is a promising approach to evaluating the tissue properties of LGN subdivisions in living humans. This method potentially will enable neuroscientific and clinical hypotheses about the human LGN to be tested.