Abstract
The posterior vertical pathway (PVP) is a set of white matter tracts that directly connect cortical regions associated with the dorsal and ventral visual streams. By traveling between action-oriented regions in the dorsal stream and perception-oriented regions in the ventral stream, white matter tracts in the PVP may be particularly important for performing tasks that link action and perception. Here, we tested whether the tissue properties of PVP white matter tracts predict learning to draw novel symbols, a motor task strongly associated with visual perception processing. Using advanced diffusion tractography, we measured fractional anisotropy (FA) in the PVP tracts (i.e., TPC, pArc, MdLF-SPL, MdLF-Ang) as well as major white matter tracts within the dorsal (i.e., SLF1and2, SLF3) and ventral streams (i.e., ILF, IFOF) in 30 adult participants before they were trained on drawing novel symbols. Training consisted of 1600 symbol drawing trials, evenly distributed over the course of 4 days. We measured learning as the trial-to-trial change in symbol drawing duration. Learning occurred most rapidly during the first day of training, with significantly less learning in the following training days. Pre-training FA in the PVP tracts that travel between the dorsal and ventral streams predicted learning; pre-training FA in tracts that travel within the dorsal and ventral streams did not significantly predict learning. Overall, our results suggest a key role for the PVP in learning that may be related to its ability to facilitate interactions between dorsal and ventral streams during action.