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Section: New Results

Surface-based fMRI data analyzes improvement

Participants : Bertrand Thirion [Correspondant] , Virgile Fritsch, Alan Tucholka.

Accuracy improvement of the functional activations found over the brain volume in fMRI experiments.

Surface-based analyses of fMRI data become more an more common since they take into account the subjects' anatomy in finding activated regions for a given task. Yet, those analyses are performed on data which actually are the projection of some original 3D data. Due to the folded shape of the human brain surface, some artifacts are hence being observed. For instance, a functional region can be projected on two different gyri, without being spread over the sulcus in-between. This can lead to some misinterpretations as the number of observed activated regions may be way too large. See for example in Fig. 2 .

In this project, we aim at providing a better accuracy in the localization of the functional activations found over the brain volume, by using a volume analysis-driven correction. We want to establish a mapping between the activations found in the volume and over the brain surface, and hence try to address - or at least, point out - some errors which have potentially been introduced by the projection step. We could thus have the neuroscientists perform more reliable interpretations of the activation maps that they obtain.

Improving the functional activations localization accuracy should at the same time improve the accuracy of the group analysis results.

Figure 2. Active regions found in the brain volume and on the cortical surface in one control subject performing a sentence listening task. While a single, well defined activity focus is observed in the volume, several surrounding active patches are found on the cortical surface. This effect can be due to a lack of precision in the projection of fMRI data to the cortical surface. in this project, we aim at detecting this effect, and possibly correcting it.
IMG/sortietex2

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