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R áegis and co-workers investigated the cerebral cortical folding pattern and proposed a generic sulcal root model based on MR imaging data of 20 normal subjects (4 females and 16 males). They tried to resolve the cortical folding pattern of the individuals using a computer three-dimensional visualization tool of the MR images. They tried to define`pli de passage' in French, which means a small gyri buried inside the deep main sulci. They hypothesized that the`pli de passage' subdivide in subunits (sulcal roots) large sulcus. Their observations are still under investigation, however, their approach using precise computer graphics is brand new. This method may be useful to understand brain function and to open new doors for brain mapping. Further improvement will be required not only for the resolution of the three dimensional MR imaging but also for the software of the image processing for the universal use of this technique. AbstractThe great variability of cerebral cortical folding patterns raises major problems for the systematic study of functional-structural relationships. This paper describes a novel perspective for explaining this variability, a perspective that relies on gyri buried in the depth of the sulci. From this perspective we propose a generic model of folding, based on indivisible units, called sulcal roots, which correspond to the first folding locations during antenatal life. These units are organized according to a basic scheme allowing us to describe the cortical surface using a system of meridians and parallels. This scheme is thought to be stable across individuals at the fetal stage, and may be related to the protomap model. Variability at the adult stage is thought to result from the chaotic behavior of the folding process: inter-individual differences in cortical areas can lead to qualitatively different folding patterns. We have tested the capacity of this model to match actual cortical anatomy with a database of magnetic resonance images of 20 normal subjects, using new three-dimensional visualization tools giving access to shapes buried in the cortex.

GK thalamotomy is an alternative treatment for intractable tremors of PD as well as for ET. Less invasive intervention may be beneficial to patients.

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