Mara Cercignani1, Giacomo Koch2,3, Carlo Caltagirone2,3, Marco Bozzali1
1Neuroimaging Laboratory, Fondazione Santa Lucia, Roma, Italy; 2Dept of Clinical and Behavioural Neurology, Fondazione Santa Lucia, Roma, Italy; 3Dept of Neuroscience, University of Rome 'Tor Vergata', Roma, Italy
We used a 'paired-pulse' transcranial stimulation (TMS) paradigm to study functional 'connections' between posterior parietal cortex (PPC) and ipsilateral motor cortex in ten healthy volunteers while planning either a whole hand grasp or a precision grip of an object. The superior longitudinal fasciculus (SLF) of every subject was reconstructed using probabilistic tractography. Facilitation due to the cortical stimulation over the PPC became evident when subjects planned a lateralized grasp, and the relative increase was correlated with the mean fractional anisotropy of the SLF, suggesting that this information is effectively mediated by this white matter pathway.