Quantitative Mapping of Human Brain Vertical-Occipital Fasciculus

PURPOSEThe vertical-occipital fasciculus (VOF), historically named as the fasciculus occipitalis verticalis of Wernicke, has been recently brought to the attention of the neuroscience community. In this study, we delineated and quantified this tract with deterministic diffusion tensor imaging protocol. METHODSFive (all males aged 24-37 years) and 10 (7 males and 3 females aged 20-51 years) right-handed healthy subjects were studied with 1 and 2 mm DT-MRI data sets, respectively. The DTI attributes of this pathway along with its cortical representation (Brodmann areas) were presented in standard Montreal Neurological Institute space. Nearby pathways such as inferior fronto-occipital (IFOF) and inferior longitudinal fasciculi (ILF) were used as reference pathways. RESULTSThe total volume of VOF has been found to be approximately .8-1% of whole brain in both data sets. The fractional anisotropy and axial diffusivity of this tract have been found to be relatively 10-15% lower than adjacent pathways such as IFOF and ILF in both data sets. Although IFOF and ILF showed somewhat leftward asymmetry in diffusivity, no right-left asymmetry has been observed in VOF. CONCLUSIONWe believe that our work will pave the way for future imaging studies investigating VOF in different conditions such as stroke, traumatic brain injury, and multiple sclerosis.