In this work, we exploited the superior capability of high-resolution functional magnetic resonance imaging (fMRI) for functional mapping of ocular dominance layer (ODL) in the cat lateral geniculate nucleus (LGN). The stimulus-evoked neuronal activities in the LGN ODLs associated with contralateral- and ipsilateral-eye visual inputs were successfully differentiated and mapped using both blood-oxygenation-level dependent (BOLD)-weighted and cerebral blood volume (CBV)-weighted fMRI methods. The morphology of mapped LGN ODLs was in remarkable consistency with histology findings in terms of ODL shape, orientation, thickness and eye-dominance. Compared with the BOLD signal, the CBV signal provides higher reproducibility and better spatial resolvability for function mapping of LGN because of improved contrast-to-noise ratio and point-spread function. The capability of fMRI for non-invasively imaging the functional sub-units of ODL in a small LGN overcomes the limitation of conventional neural-recording approach, and it opens a new opportunity for studying critical roles of LGN in brain function and dysfunction at the fine scale of ocular dominance layer.
Bibliographical noteFunding Information:
We thank Dr. Kamil Ugurbil for support and Dr. Xiaoliang Zhang for his help in RF coil design and construction. This work was supported in part by NIH grants of NS041262 , NS041262S1 , EB000329 , EB000513 , NS057560 , P41 RR08079 and P30NS057091 ; and the Keck Foundation.
- Blood-oxygenation-level-dependent (BOLD)
- Cerebral blood volume (CBV)
- Functional MRI (fMRI)
- Lateral geniculate nucleus (LGN)
- Ocular dominance layer (ODL)